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1/*P:100
2 * This is the Launcher code, a simple program which lays out the "physical"
3 * memory for the new Guest by mapping the kernel image and the virtual
4 * devices, then opens /dev/lguest to tell the kernel about the Guest and
5 * control it.
6:*/
7#define _LARGEFILE64_SOURCE
8#define _GNU_SOURCE
9#include <stdio.h>
10#include <string.h>
11#include <unistd.h>
12#include <err.h>
13#include <stdint.h>
14#include <stdlib.h>
15#include <elf.h>
16#include <sys/mman.h>
17#include <sys/param.h>
18#include <sys/types.h>
19#include <sys/stat.h>
20#include <sys/wait.h>
21#include <sys/eventfd.h>
22#include <fcntl.h>
23#include <stdbool.h>
24#include <errno.h>
25#include <ctype.h>
26#include <sys/socket.h>
27#include <sys/ioctl.h>
28#include <sys/time.h>
29#include <time.h>
30#include <netinet/in.h>
31#include <net/if.h>
32#include <linux/sockios.h>
33#include <linux/if_tun.h>
34#include <sys/uio.h>
35#include <termios.h>
36#include <getopt.h>
37#include <assert.h>
38#include <sched.h>
39#include <limits.h>
40#include <stddef.h>
41#include <signal.h>
42#include <pwd.h>
43#include <grp.h>
44#include <sys/user.h>
45#include <linux/pci_regs.h>
46
47#ifndef VIRTIO_F_ANY_LAYOUT
48#define VIRTIO_F_ANY_LAYOUT 27
49#endif
50
51/*L:110
52 * We can ignore the 43 include files we need for this program, but I do want
53 * to draw attention to the use of kernel-style types.
54 *
55 * As Linus said, "C is a Spartan language, and so should your naming be." I
56 * like these abbreviations, so we define them here. Note that u64 is always
57 * unsigned long long, which works on all Linux systems: this means that we can
58 * use %llu in printf for any u64.
59 */
60typedef unsigned long long u64;
61typedef uint32_t u32;
62typedef uint16_t u16;
63typedef uint8_t u8;
64/*:*/
65
66#define VIRTIO_CONFIG_NO_LEGACY
67#define VIRTIO_PCI_NO_LEGACY
68#define VIRTIO_BLK_NO_LEGACY
69#define VIRTIO_NET_NO_LEGACY
70
71/* Use in-kernel ones, which defines VIRTIO_F_VERSION_1 */
72#include "../../include/uapi/linux/virtio_config.h"
73#include "../../include/uapi/linux/virtio_net.h"
74#include "../../include/uapi/linux/virtio_blk.h"
75#include "../../include/uapi/linux/virtio_console.h"
76#include "../../include/uapi/linux/virtio_rng.h"
77#include <linux/virtio_ring.h>
78#include "../../include/uapi/linux/virtio_pci.h"
79#include <asm/bootparam.h>
80#include "../../include/linux/lguest_launcher.h"
81
82#define BRIDGE_PFX "bridge:"
83#ifndef SIOCBRADDIF
84#define SIOCBRADDIF 0x89a2 /* add interface to bridge */
85#endif
86/* We can have up to 256 pages for devices. */
87#define DEVICE_PAGES 256
88/* This will occupy 3 pages: it must be a power of 2. */
89#define VIRTQUEUE_NUM 256
90
91/*L:120
92 * verbose is both a global flag and a macro. The C preprocessor allows
93 * this, and although I wouldn't recommend it, it works quite nicely here.
94 */
95static bool verbose;
96#define verbose(args...) \
97 do { if (verbose) printf(args); } while(0)
98/*:*/
99
100/* The pointer to the start of guest memory. */
101static void *guest_base;
102/* The maximum guest physical address allowed, and maximum possible. */
103static unsigned long guest_limit, guest_max, guest_mmio;
104/* The /dev/lguest file descriptor. */
105static int lguest_fd;
106
107/* a per-cpu variable indicating whose vcpu is currently running */
108static unsigned int __thread cpu_id;
109
110/* 5 bit device number in the PCI_CONFIG_ADDR => 32 only */
111#define MAX_PCI_DEVICES 32
112
113/* This is our list of devices. */
114struct device_list {
115 /* Counter to assign interrupt numbers. */
116 unsigned int next_irq;
117
118 /* Counter to print out convenient device numbers. */
119 unsigned int device_num;
120
121 /* PCI devices. */
122 struct device *pci[MAX_PCI_DEVICES];
123};
124
125/* The list of Guest devices, based on command line arguments. */
126static struct device_list devices;
127
128/*
129 * Just like struct virtio_pci_cfg_cap in uapi/linux/virtio_pci.h,
130 * but uses a u32 explicitly for the data.
131 */
132struct virtio_pci_cfg_cap_u32 {
133 struct virtio_pci_cap cap;
134 u32 pci_cfg_data; /* Data for BAR access. */
135};
136
137struct virtio_pci_mmio {
138 struct virtio_pci_common_cfg cfg;
139 u16 notify;
140 u8 isr;
141 u8 padding;
142 /* Device-specific configuration follows this. */
143};
144
145/* This is the layout (little-endian) of the PCI config space. */
146struct pci_config {
147 u16 vendor_id, device_id;
148 u16 command, status;
149 u8 revid, prog_if, subclass, class;
150 u8 cacheline_size, lat_timer, header_type, bist;
151 u32 bar[6];
152 u32 cardbus_cis_ptr;
153 u16 subsystem_vendor_id, subsystem_device_id;
154 u32 expansion_rom_addr;
155 u8 capabilities, reserved1[3];
156 u32 reserved2;
157 u8 irq_line, irq_pin, min_grant, max_latency;
158
159 /* Now, this is the linked capability list. */
160 struct virtio_pci_cap common;
161 struct virtio_pci_notify_cap notify;
162 struct virtio_pci_cap isr;
163 struct virtio_pci_cap device;
164 struct virtio_pci_cfg_cap_u32 cfg_access;
165};
166
167/* The device structure describes a single device. */
168struct device {
169 /* The name of this device, for --verbose. */
170 const char *name;
171
172 /* Any queues attached to this device */
173 struct virtqueue *vq;
174
175 /* Is it operational */
176 bool running;
177
178 /* Has it written FEATURES_OK but not re-checked it? */
179 bool wrote_features_ok;
180
181 /* PCI configuration */
182 union {
183 struct pci_config config;
184 u32 config_words[sizeof(struct pci_config) / sizeof(u32)];
185 };
186
187 /* Features we offer, and those accepted. */
188 u64 features, features_accepted;
189
190 /* Device-specific config hangs off the end of this. */
191 struct virtio_pci_mmio *mmio;
192
193 /* PCI MMIO resources (all in BAR0) */
194 size_t mmio_size;
195 u32 mmio_addr;
196
197 /* Device-specific data. */
198 void *priv;
199};
200
201/* The virtqueue structure describes a queue attached to a device. */
202struct virtqueue {
203 struct virtqueue *next;
204
205 /* Which device owns me. */
206 struct device *dev;
207
208 /* Name for printing errors. */
209 const char *name;
210
211 /* The actual ring of buffers. */
212 struct vring vring;
213
214 /* The information about this virtqueue (we only use queue_size on) */
215 struct virtio_pci_common_cfg pci_config;
216
217 /* Last available index we saw. */
218 u16 last_avail_idx;
219
220 /* How many are used since we sent last irq? */
221 unsigned int pending_used;
222
223 /* Eventfd where Guest notifications arrive. */
224 int eventfd;
225
226 /* Function for the thread which is servicing this virtqueue. */
227 void (*service)(struct virtqueue *vq);
228 pid_t thread;
229};
230
231/* Remember the arguments to the program so we can "reboot" */
232static char **main_args;
233
234/* The original tty settings to restore on exit. */
235static struct termios orig_term;
236
237/*
238 * We have to be careful with barriers: our devices are all run in separate
239 * threads and so we need to make sure that changes visible to the Guest happen
240 * in precise order.
241 */
242#define wmb() __asm__ __volatile__("" : : : "memory")
243#define rmb() __asm__ __volatile__("lock; addl $0,0(%%esp)" : : : "memory")
244#define mb() __asm__ __volatile__("lock; addl $0,0(%%esp)" : : : "memory")
245
246/* Wrapper for the last available index. Makes it easier to change. */
247#define lg_last_avail(vq) ((vq)->last_avail_idx)
248
249/*
250 * The virtio configuration space is defined to be little-endian. x86 is
251 * little-endian too, but it's nice to be explicit so we have these helpers.
252 */
253#define cpu_to_le16(v16) (v16)
254#define cpu_to_le32(v32) (v32)
255#define cpu_to_le64(v64) (v64)
256#define le16_to_cpu(v16) (v16)
257#define le32_to_cpu(v32) (v32)
258#define le64_to_cpu(v64) (v64)
259
260/*
261 * A real device would ignore weird/non-compliant driver behaviour. We
262 * stop and flag it, to help debugging Linux problems.
263 */
264#define bad_driver(d, fmt, ...) \
265 errx(1, "%s: bad driver: " fmt, (d)->name, ## __VA_ARGS__)
266#define bad_driver_vq(vq, fmt, ...) \
267 errx(1, "%s vq %s: bad driver: " fmt, (vq)->dev->name, \
268 vq->name, ## __VA_ARGS__)
269
270/* Is this iovec empty? */
271static bool iov_empty(const struct iovec iov[], unsigned int num_iov)
272{
273 unsigned int i;
274
275 for (i = 0; i < num_iov; i++)
276 if (iov[i].iov_len)
277 return false;
278 return true;
279}
280
281/* Take len bytes from the front of this iovec. */
282static void iov_consume(struct device *d,
283 struct iovec iov[], unsigned num_iov,
284 void *dest, unsigned len)
285{
286 unsigned int i;
287
288 for (i = 0; i < num_iov; i++) {
289 unsigned int used;
290
291 used = iov[i].iov_len < len ? iov[i].iov_len : len;
292 if (dest) {
293 memcpy(dest, iov[i].iov_base, used);
294 dest += used;
295 }
296 iov[i].iov_base += used;
297 iov[i].iov_len -= used;
298 len -= used;
299 }
300 if (len != 0)
301 bad_driver(d, "iovec too short!");
302}
303
304/*L:100
305 * The Launcher code itself takes us out into userspace, that scary place where
306 * pointers run wild and free! Unfortunately, like most userspace programs,
307 * it's quite boring (which is why everyone likes to hack on the kernel!).
308 * Perhaps if you make up an Lguest Drinking Game at this point, it will get
309 * you through this section. Or, maybe not.
310 *
311 * The Launcher sets up a big chunk of memory to be the Guest's "physical"
312 * memory and stores it in "guest_base". In other words, Guest physical ==
313 * Launcher virtual with an offset.
314 *
315 * This can be tough to get your head around, but usually it just means that we
316 * use these trivial conversion functions when the Guest gives us its
317 * "physical" addresses:
318 */
319static void *from_guest_phys(unsigned long addr)
320{
321 return guest_base + addr;
322}
323
324static unsigned long to_guest_phys(const void *addr)
325{
326 return (addr - guest_base);
327}
328
329/*L:130
330 * Loading the Kernel.
331 *
332 * We start with couple of simple helper routines. open_or_die() avoids
333 * error-checking code cluttering the callers:
334 */
335static int open_or_die(const char *name, int flags)
336{
337 int fd = open(name, flags);
338 if (fd < 0)
339 err(1, "Failed to open %s", name);
340 return fd;
341}
342
343/* map_zeroed_pages() takes a number of pages. */
344static void *map_zeroed_pages(unsigned int num)
345{
346 int fd = open_or_die("/dev/zero", O_RDONLY);
347 void *addr;
348
349 /*
350 * We use a private mapping (ie. if we write to the page, it will be
351 * copied). We allocate an extra two pages PROT_NONE to act as guard
352 * pages against read/write attempts that exceed allocated space.
353 */
354 addr = mmap(NULL, getpagesize() * (num+2),
355 PROT_NONE, MAP_PRIVATE, fd, 0);
356
357 if (addr == MAP_FAILED)
358 err(1, "Mmapping %u pages of /dev/zero", num);
359
360 if (mprotect(addr + getpagesize(), getpagesize() * num,
361 PROT_READ|PROT_WRITE) == -1)
362 err(1, "mprotect rw %u pages failed", num);
363
364 /*
365 * One neat mmap feature is that you can close the fd, and it
366 * stays mapped.
367 */
368 close(fd);
369
370 /* Return address after PROT_NONE page */
371 return addr + getpagesize();
372}
373
374/* Get some bytes which won't be mapped into the guest. */
375static unsigned long get_mmio_region(size_t size)
376{
377 unsigned long addr = guest_mmio;
378 size_t i;
379
380 if (!size)
381 return addr;
382
383 /* Size has to be a power of 2 (and multiple of 16) */
384 for (i = 1; i < size; i <<= 1);
385
386 guest_mmio += i;
387
388 return addr;
389}
390
391/*
392 * This routine is used to load the kernel or initrd. It tries mmap, but if
393 * that fails (Plan 9's kernel file isn't nicely aligned on page boundaries),
394 * it falls back to reading the memory in.
395 */
396static void map_at(int fd, void *addr, unsigned long offset, unsigned long len)
397{
398 ssize_t r;
399
400 /*
401 * We map writable even though for some segments are marked read-only.
402 * The kernel really wants to be writable: it patches its own
403 * instructions.
404 *
405 * MAP_PRIVATE means that the page won't be copied until a write is
406 * done to it. This allows us to share untouched memory between
407 * Guests.
408 */
409 if (mmap(addr, len, PROT_READ|PROT_WRITE,
410 MAP_FIXED|MAP_PRIVATE, fd, offset) != MAP_FAILED)
411 return;
412
413 /* pread does a seek and a read in one shot: saves a few lines. */
414 r = pread(fd, addr, len, offset);
415 if (r != len)
416 err(1, "Reading offset %lu len %lu gave %zi", offset, len, r);
417}
418
419/*
420 * This routine takes an open vmlinux image, which is in ELF, and maps it into
421 * the Guest memory. ELF = Embedded Linking Format, which is the format used
422 * by all modern binaries on Linux including the kernel.
423 *
424 * The ELF headers give *two* addresses: a physical address, and a virtual
425 * address. We use the physical address; the Guest will map itself to the
426 * virtual address.
427 *
428 * We return the starting address.
429 */
430static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr)
431{
432 Elf32_Phdr phdr[ehdr->e_phnum];
433 unsigned int i;
434
435 /*
436 * Sanity checks on the main ELF header: an x86 executable with a
437 * reasonable number of correctly-sized program headers.
438 */
439 if (ehdr->e_type != ET_EXEC
440 || ehdr->e_machine != EM_386
441 || ehdr->e_phentsize != sizeof(Elf32_Phdr)
442 || ehdr->e_phnum < 1 || ehdr->e_phnum > 65536U/sizeof(Elf32_Phdr))
443 errx(1, "Malformed elf header");
444
445 /*
446 * An ELF executable contains an ELF header and a number of "program"
447 * headers which indicate which parts ("segments") of the program to
448 * load where.
449 */
450
451 /* We read in all the program headers at once: */
452 if (lseek(elf_fd, ehdr->e_phoff, SEEK_SET) < 0)
453 err(1, "Seeking to program headers");
454 if (read(elf_fd, phdr, sizeof(phdr)) != sizeof(phdr))
455 err(1, "Reading program headers");
456
457 /*
458 * Try all the headers: there are usually only three. A read-only one,
459 * a read-write one, and a "note" section which we don't load.
460 */
461 for (i = 0; i < ehdr->e_phnum; i++) {
462 /* If this isn't a loadable segment, we ignore it */
463 if (phdr[i].p_type != PT_LOAD)
464 continue;
465
466 verbose("Section %i: size %i addr %p\n",
467 i, phdr[i].p_memsz, (void *)phdr[i].p_paddr);
468
469 /* We map this section of the file at its physical address. */
470 map_at(elf_fd, from_guest_phys(phdr[i].p_paddr),
471 phdr[i].p_offset, phdr[i].p_filesz);
472 }
473
474 /* The entry point is given in the ELF header. */
475 return ehdr->e_entry;
476}
477
478/*L:150
479 * A bzImage, unlike an ELF file, is not meant to be loaded. You're supposed
480 * to jump into it and it will unpack itself. We used to have to perform some
481 * hairy magic because the unpacking code scared me.
482 *
483 * Fortunately, Jeremy Fitzhardinge convinced me it wasn't that hard and wrote
484 * a small patch to jump over the tricky bits in the Guest, so now we just read
485 * the funky header so we know where in the file to load, and away we go!
486 */
487static unsigned long load_bzimage(int fd)
488{
489 struct boot_params boot;
490 int r;
491 /* Modern bzImages get loaded at 1M. */
492 void *p = from_guest_phys(0x100000);
493
494 /*
495 * Go back to the start of the file and read the header. It should be
496 * a Linux boot header (see Documentation/x86/boot.txt)
497 */
498 lseek(fd, 0, SEEK_SET);
499 read(fd, &boot, sizeof(boot));
500
501 /* Inside the setup_hdr, we expect the magic "HdrS" */
502 if (memcmp(&boot.hdr.header, "HdrS", 4) != 0)
503 errx(1, "This doesn't look like a bzImage to me");
504
505 /* Skip over the extra sectors of the header. */
506 lseek(fd, (boot.hdr.setup_sects+1) * 512, SEEK_SET);
507
508 /* Now read everything into memory. in nice big chunks. */
509 while ((r = read(fd, p, 65536)) > 0)
510 p += r;
511
512 /* Finally, code32_start tells us where to enter the kernel. */
513 return boot.hdr.code32_start;
514}
515
516/*L:140
517 * Loading the kernel is easy when it's a "vmlinux", but most kernels
518 * come wrapped up in the self-decompressing "bzImage" format. With a little
519 * work, we can load those, too.
520 */
521static unsigned long load_kernel(int fd)
522{
523 Elf32_Ehdr hdr;
524
525 /* Read in the first few bytes. */
526 if (read(fd, &hdr, sizeof(hdr)) != sizeof(hdr))
527 err(1, "Reading kernel");
528
529 /* If it's an ELF file, it starts with "\177ELF" */
530 if (memcmp(hdr.e_ident, ELFMAG, SELFMAG) == 0)
531 return map_elf(fd, &hdr);
532
533 /* Otherwise we assume it's a bzImage, and try to load it. */
534 return load_bzimage(fd);
535}
536
537/*
538 * This is a trivial little helper to align pages. Andi Kleen hated it because
539 * it calls getpagesize() twice: "it's dumb code."
540 *
541 * Kernel guys get really het up about optimization, even when it's not
542 * necessary. I leave this code as a reaction against that.
543 */
544static inline unsigned long page_align(unsigned long addr)
545{
546 /* Add upwards and truncate downwards. */
547 return ((addr + getpagesize()-1) & ~(getpagesize()-1));
548}
549
550/*L:180
551 * An "initial ram disk" is a disk image loaded into memory along with the
552 * kernel which the kernel can use to boot from without needing any drivers.
553 * Most distributions now use this as standard: the initrd contains the code to
554 * load the appropriate driver modules for the current machine.
555 *
556 * Importantly, James Morris works for RedHat, and Fedora uses initrds for its
557 * kernels. He sent me this (and tells me when I break it).
558 */
559static unsigned long load_initrd(const char *name, unsigned long mem)
560{
561 int ifd;
562 struct stat st;
563 unsigned long len;
564
565 ifd = open_or_die(name, O_RDONLY);
566 /* fstat() is needed to get the file size. */
567 if (fstat(ifd, &st) < 0)
568 err(1, "fstat() on initrd '%s'", name);
569
570 /*
571 * We map the initrd at the top of memory, but mmap wants it to be
572 * page-aligned, so we round the size up for that.
573 */
574 len = page_align(st.st_size);
575 map_at(ifd, from_guest_phys(mem - len), 0, st.st_size);
576 /*
577 * Once a file is mapped, you can close the file descriptor. It's a
578 * little odd, but quite useful.
579 */
580 close(ifd);
581 verbose("mapped initrd %s size=%lu @ %p\n", name, len, (void*)mem-len);
582
583 /* We return the initrd size. */
584 return len;
585}
586/*:*/
587
588/*
589 * Simple routine to roll all the commandline arguments together with spaces
590 * between them.
591 */
592static void concat(char *dst, char *args[])
593{
594 unsigned int i, len = 0;
595
596 for (i = 0; args[i]; i++) {
597 if (i) {
598 strcat(dst+len, " ");
599 len++;
600 }
601 strcpy(dst+len, args[i]);
602 len += strlen(args[i]);
603 }
604 /* In case it's empty. */
605 dst[len] = '\0';
606}
607
608/*L:185
609 * This is where we actually tell the kernel to initialize the Guest. We
610 * saw the arguments it expects when we looked at initialize() in lguest_user.c:
611 * the base of Guest "physical" memory, the top physical page to allow and the
612 * entry point for the Guest.
613 */
614static void tell_kernel(unsigned long start)
615{
616 unsigned long args[] = { LHREQ_INITIALIZE,
617 (unsigned long)guest_base,
618 guest_limit / getpagesize(), start,
619 (guest_mmio+getpagesize()-1) / getpagesize() };
620 verbose("Guest: %p - %p (%#lx, MMIO %#lx)\n",
621 guest_base, guest_base + guest_limit,
622 guest_limit, guest_mmio);
623 lguest_fd = open_or_die("/dev/lguest", O_RDWR);
624 if (write(lguest_fd, args, sizeof(args)) < 0)
625 err(1, "Writing to /dev/lguest");
626}
627/*:*/
628
629/*L:200
630 * Device Handling.
631 *
632 * When the Guest gives us a buffer, it sends an array of addresses and sizes.
633 * We need to make sure it's not trying to reach into the Launcher itself, so
634 * we have a convenient routine which checks it and exits with an error message
635 * if something funny is going on:
636 */
637static void *_check_pointer(struct device *d,
638 unsigned long addr, unsigned int size,
639 unsigned int line)
640{
641 /*
642 * Check if the requested address and size exceeds the allocated memory,
643 * or addr + size wraps around.
644 */
645 if ((addr + size) > guest_limit || (addr + size) < addr)
646 bad_driver(d, "%s:%i: Invalid address %#lx",
647 __FILE__, line, addr);
648 /*
649 * We return a pointer for the caller's convenience, now we know it's
650 * safe to use.
651 */
652 return from_guest_phys(addr);
653}
654/* A macro which transparently hands the line number to the real function. */
655#define check_pointer(d,addr,size) _check_pointer(d, addr, size, __LINE__)
656
657/*
658 * Each buffer in the virtqueues is actually a chain of descriptors. This
659 * function returns the next descriptor in the chain, or vq->vring.num if we're
660 * at the end.
661 */
662static unsigned next_desc(struct device *d, struct vring_desc *desc,
663 unsigned int i, unsigned int max)
664{
665 unsigned int next;
666
667 /* If this descriptor says it doesn't chain, we're done. */
668 if (!(desc[i].flags & VRING_DESC_F_NEXT))
669 return max;
670
671 /* Check they're not leading us off end of descriptors. */
672 next = desc[i].next;
673 /* Make sure compiler knows to grab that: we don't want it changing! */
674 wmb();
675
676 if (next >= max)
677 bad_driver(d, "Desc next is %u", next);
678
679 return next;
680}
681
682/*
683 * This actually sends the interrupt for this virtqueue, if we've used a
684 * buffer.
685 */
686static void trigger_irq(struct virtqueue *vq)
687{
688 unsigned long buf[] = { LHREQ_IRQ, vq->dev->config.irq_line };
689
690 /* Don't inform them if nothing used. */
691 if (!vq->pending_used)
692 return;
693 vq->pending_used = 0;
694
695 /*
696 * 2.4.7.1:
697 *
698 * If the VIRTIO_F_EVENT_IDX feature bit is not negotiated:
699 * The driver MUST set flags to 0 or 1.
700 */
701 if (vq->vring.avail->flags > 1)
702 bad_driver_vq(vq, "avail->flags = %u\n", vq->vring.avail->flags);
703
704 /*
705 * 2.4.7.2:
706 *
707 * If the VIRTIO_F_EVENT_IDX feature bit is not negotiated:
708 *
709 * - The device MUST ignore the used_event value.
710 * - After the device writes a descriptor index into the used ring:
711 * - If flags is 1, the device SHOULD NOT send an interrupt.
712 * - If flags is 0, the device MUST send an interrupt.
713 */
714 if (vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT) {
715 return;
716 }
717
718 /*
719 * 4.1.4.5.1:
720 *
721 * If MSI-X capability is disabled, the device MUST set the Queue
722 * Interrupt bit in ISR status before sending a virtqueue notification
723 * to the driver.
724 */
725 vq->dev->mmio->isr = 0x1;
726
727 /* Send the Guest an interrupt tell them we used something up. */
728 if (write(lguest_fd, buf, sizeof(buf)) != 0)
729 err(1, "Triggering irq %i", vq->dev->config.irq_line);
730}
731
732/*
733 * This looks in the virtqueue for the first available buffer, and converts
734 * it to an iovec for convenient access. Since descriptors consist of some
735 * number of output then some number of input descriptors, it's actually two
736 * iovecs, but we pack them into one and note how many of each there were.
737 *
738 * This function waits if necessary, and returns the descriptor number found.
739 */
740static unsigned wait_for_vq_desc(struct virtqueue *vq,
741 struct iovec iov[],
742 unsigned int *out_num, unsigned int *in_num)
743{
744 unsigned int i, head, max;
745 struct vring_desc *desc;
746 u16 last_avail = lg_last_avail(vq);
747
748 /*
749 * 2.4.7.1:
750 *
751 * The driver MUST handle spurious interrupts from the device.
752 *
753 * That's why this is a while loop.
754 */
755
756 /* There's nothing available? */
757 while (last_avail == vq->vring.avail->idx) {
758 u64 event;
759
760 /*
761 * Since we're about to sleep, now is a good time to tell the
762 * Guest about what we've used up to now.
763 */
764 trigger_irq(vq);
765
766 /* OK, now we need to know about added descriptors. */
767 vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY;
768
769 /*
770 * They could have slipped one in as we were doing that: make
771 * sure it's written, then check again.
772 */
773 mb();
774 if (last_avail != vq->vring.avail->idx) {
775 vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY;
776 break;
777 }
778
779 /* Nothing new? Wait for eventfd to tell us they refilled. */
780 if (read(vq->eventfd, &event, sizeof(event)) != sizeof(event))
781 errx(1, "Event read failed?");
782
783 /* We don't need to be notified again. */
784 vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY;
785 }
786
787 /* Check it isn't doing very strange things with descriptor numbers. */
788 if ((u16)(vq->vring.avail->idx - last_avail) > vq->vring.num)
789 bad_driver_vq(vq, "Guest moved used index from %u to %u",
790 last_avail, vq->vring.avail->idx);
791
792 /*
793 * Make sure we read the descriptor number *after* we read the ring
794 * update; don't let the cpu or compiler change the order.
795 */
796 rmb();
797
798 /*
799 * Grab the next descriptor number they're advertising, and increment
800 * the index we've seen.
801 */
802 head = vq->vring.avail->ring[last_avail % vq->vring.num];
803 lg_last_avail(vq)++;
804
805 /* If their number is silly, that's a fatal mistake. */
806 if (head >= vq->vring.num)
807 bad_driver_vq(vq, "Guest says index %u is available", head);
808
809 /* When we start there are none of either input nor output. */
810 *out_num = *in_num = 0;
811
812 max = vq->vring.num;
813 desc = vq->vring.desc;
814 i = head;
815
816 /*
817 * We have to read the descriptor after we read the descriptor number,
818 * but there's a data dependency there so the CPU shouldn't reorder
819 * that: no rmb() required.
820 */
821
822 do {
823 /*
824 * If this is an indirect entry, then this buffer contains a
825 * descriptor table which we handle as if it's any normal
826 * descriptor chain.
827 */
828 if (desc[i].flags & VRING_DESC_F_INDIRECT) {
829 /* 2.4.5.3.1:
830 *
831 * The driver MUST NOT set the VIRTQ_DESC_F_INDIRECT
832 * flag unless the VIRTIO_F_INDIRECT_DESC feature was
833 * negotiated.
834 */
835 if (!(vq->dev->features_accepted &
836 (1<<VIRTIO_RING_F_INDIRECT_DESC)))
837 bad_driver_vq(vq, "vq indirect not negotiated");
838
839 /*
840 * 2.4.5.3.1:
841 *
842 * The driver MUST NOT set the VIRTQ_DESC_F_INDIRECT
843 * flag within an indirect descriptor (ie. only one
844 * table per descriptor).
845 */
846 if (desc != vq->vring.desc)
847 bad_driver_vq(vq, "Indirect within indirect");
848
849 /*
850 * Proposed update VIRTIO-134 spells this out:
851 *
852 * A driver MUST NOT set both VIRTQ_DESC_F_INDIRECT
853 * and VIRTQ_DESC_F_NEXT in flags.
854 */
855 if (desc[i].flags & VRING_DESC_F_NEXT)
856 bad_driver_vq(vq, "indirect and next together");
857
858 if (desc[i].len % sizeof(struct vring_desc))
859 bad_driver_vq(vq,
860 "Invalid size for indirect table");
861 /*
862 * 2.4.5.3.2:
863 *
864 * The device MUST ignore the write-only flag
865 * (flags&VIRTQ_DESC_F_WRITE) in the descriptor that
866 * refers to an indirect table.
867 *
868 * We ignore it here: :)
869 */
870
871 max = desc[i].len / sizeof(struct vring_desc);
872 desc = check_pointer(vq->dev, desc[i].addr, desc[i].len);
873 i = 0;
874
875 /* 2.4.5.3.1:
876 *
877 * A driver MUST NOT create a descriptor chain longer
878 * than the Queue Size of the device.
879 */
880 if (max > vq->pci_config.queue_size)
881 bad_driver_vq(vq,
882 "indirect has too many entries");
883 }
884
885 /* Grab the first descriptor, and check it's OK. */
886 iov[*out_num + *in_num].iov_len = desc[i].len;
887 iov[*out_num + *in_num].iov_base
888 = check_pointer(vq->dev, desc[i].addr, desc[i].len);
889 /* If this is an input descriptor, increment that count. */
890 if (desc[i].flags & VRING_DESC_F_WRITE)
891 (*in_num)++;
892 else {
893 /*
894 * If it's an output descriptor, they're all supposed
895 * to come before any input descriptors.
896 */
897 if (*in_num)
898 bad_driver_vq(vq,
899 "Descriptor has out after in");
900 (*out_num)++;
901 }
902
903 /* If we've got too many, that implies a descriptor loop. */
904 if (*out_num + *in_num > max)
905 bad_driver_vq(vq, "Looped descriptor");
906 } while ((i = next_desc(vq->dev, desc, i, max)) != max);
907
908 return head;
909}
910
911/*
912 * After we've used one of their buffers, we tell the Guest about it. Sometime
913 * later we'll want to send them an interrupt using trigger_irq(); note that
914 * wait_for_vq_desc() does that for us if it has to wait.
915 */
916static void add_used(struct virtqueue *vq, unsigned int head, int len)
917{
918 struct vring_used_elem *used;
919
920 /*
921 * The virtqueue contains a ring of used buffers. Get a pointer to the
922 * next entry in that used ring.
923 */
924 used = &vq->vring.used->ring[vq->vring.used->idx % vq->vring.num];
925 used->id = head;
926 used->len = len;
927 /* Make sure buffer is written before we update index. */
928 wmb();
929 vq->vring.used->idx++;
930 vq->pending_used++;
931}
932
933/* And here's the combo meal deal. Supersize me! */
934static void add_used_and_trigger(struct virtqueue *vq, unsigned head, int len)
935{
936 add_used(vq, head, len);
937 trigger_irq(vq);
938}
939
940/*
941 * The Console
942 *
943 * We associate some data with the console for our exit hack.
944 */
945struct console_abort {
946 /* How many times have they hit ^C? */
947 int count;
948 /* When did they start? */
949 struct timeval start;
950};
951
952/* This is the routine which handles console input (ie. stdin). */
953static void console_input(struct virtqueue *vq)
954{
955 int len;
956 unsigned int head, in_num, out_num;
957 struct console_abort *abort = vq->dev->priv;
958 struct iovec iov[vq->vring.num];
959
960 /* Make sure there's a descriptor available. */
961 head = wait_for_vq_desc(vq, iov, &out_num, &in_num);
962 if (out_num)
963 bad_driver_vq(vq, "Output buffers in console in queue?");
964
965 /* Read into it. This is where we usually wait. */
966 len = readv(STDIN_FILENO, iov, in_num);
967 if (len <= 0) {
968 /* Ran out of input? */
969 warnx("Failed to get console input, ignoring console.");
970 /*
971 * For simplicity, dying threads kill the whole Launcher. So
972 * just nap here.
973 */
974 for (;;)
975 pause();
976 }
977
978 /* Tell the Guest we used a buffer. */
979 add_used_and_trigger(vq, head, len);
980
981 /*
982 * Three ^C within one second? Exit.
983 *
984 * This is such a hack, but works surprisingly well. Each ^C has to
985 * be in a buffer by itself, so they can't be too fast. But we check
986 * that we get three within about a second, so they can't be too
987 * slow.
988 */
989 if (len != 1 || ((char *)iov[0].iov_base)[0] != 3) {
990 abort->count = 0;
991 return;
992 }
993
994 abort->count++;
995 if (abort->count == 1)
996 gettimeofday(&abort->start, NULL);
997 else if (abort->count == 3) {
998 struct timeval now;
999 gettimeofday(&now, NULL);
1000 /* Kill all Launcher processes with SIGINT, like normal ^C */
1001 if (now.tv_sec <= abort->start.tv_sec+1)
1002 kill(0, SIGINT);
1003 abort->count = 0;
1004 }
1005}
1006
1007/* This is the routine which handles console output (ie. stdout). */
1008static void console_output(struct virtqueue *vq)
1009{
1010 unsigned int head, out, in;
1011 struct iovec iov[vq->vring.num];
1012
1013 /* We usually wait in here, for the Guest to give us something. */
1014 head = wait_for_vq_desc(vq, iov, &out, &in);
1015 if (in)
1016 bad_driver_vq(vq, "Input buffers in console output queue?");
1017
1018 /* writev can return a partial write, so we loop here. */
1019 while (!iov_empty(iov, out)) {
1020 int len = writev(STDOUT_FILENO, iov, out);
1021 if (len <= 0) {
1022 warn("Write to stdout gave %i (%d)", len, errno);
1023 break;
1024 }
1025 iov_consume(vq->dev, iov, out, NULL, len);
1026 }
1027
1028 /*
1029 * We're finished with that buffer: if we're going to sleep,
1030 * wait_for_vq_desc() will prod the Guest with an interrupt.
1031 */
1032 add_used(vq, head, 0);
1033}
1034
1035/*
1036 * The Network
1037 *
1038 * Handling output for network is also simple: we get all the output buffers
1039 * and write them to /dev/net/tun.
1040 */
1041struct net_info {
1042 int tunfd;
1043};
1044
1045static void net_output(struct virtqueue *vq)
1046{
1047 struct net_info *net_info = vq->dev->priv;
1048 unsigned int head, out, in;
1049 struct iovec iov[vq->vring.num];
1050
1051 /* We usually wait in here for the Guest to give us a packet. */
1052 head = wait_for_vq_desc(vq, iov, &out, &in);
1053 if (in)
1054 bad_driver_vq(vq, "Input buffers in net output queue?");
1055 /*
1056 * Send the whole thing through to /dev/net/tun. It expects the exact
1057 * same format: what a coincidence!
1058 */
1059 if (writev(net_info->tunfd, iov, out) < 0)
1060 warnx("Write to tun failed (%d)?", errno);
1061
1062 /*
1063 * Done with that one; wait_for_vq_desc() will send the interrupt if
1064 * all packets are processed.
1065 */
1066 add_used(vq, head, 0);
1067}
1068
1069/*
1070 * Handling network input is a bit trickier, because I've tried to optimize it.
1071 *
1072 * First we have a helper routine which tells is if from this file descriptor
1073 * (ie. the /dev/net/tun device) will block:
1074 */
1075static bool will_block(int fd)
1076{
1077 fd_set fdset;
1078 struct timeval zero = { 0, 0 };
1079 FD_ZERO(&fdset);
1080 FD_SET(fd, &fdset);
1081 return select(fd+1, &fdset, NULL, NULL, &zero) != 1;
1082}
1083
1084/*
1085 * This handles packets coming in from the tun device to our Guest. Like all
1086 * service routines, it gets called again as soon as it returns, so you don't
1087 * see a while(1) loop here.
1088 */
1089static void net_input(struct virtqueue *vq)
1090{
1091 int len;
1092 unsigned int head, out, in;
1093 struct iovec iov[vq->vring.num];
1094 struct net_info *net_info = vq->dev->priv;
1095
1096 /*
1097 * Get a descriptor to write an incoming packet into. This will also
1098 * send an interrupt if they're out of descriptors.
1099 */
1100 head = wait_for_vq_desc(vq, iov, &out, &in);
1101 if (out)
1102 bad_driver_vq(vq, "Output buffers in net input queue?");
1103
1104 /*
1105 * If it looks like we'll block reading from the tun device, send them
1106 * an interrupt.
1107 */
1108 if (vq->pending_used && will_block(net_info->tunfd))
1109 trigger_irq(vq);
1110
1111 /*
1112 * Read in the packet. This is where we normally wait (when there's no
1113 * incoming network traffic).
1114 */
1115 len = readv(net_info->tunfd, iov, in);
1116 if (len <= 0)
1117 warn("Failed to read from tun (%d).", errno);
1118
1119 /*
1120 * Mark that packet buffer as used, but don't interrupt here. We want
1121 * to wait until we've done as much work as we can.
1122 */
1123 add_used(vq, head, len);
1124}
1125/*:*/
1126
1127/* This is the helper to create threads: run the service routine in a loop. */
1128static int do_thread(void *_vq)
1129{
1130 struct virtqueue *vq = _vq;
1131
1132 for (;;)
1133 vq->service(vq);
1134 return 0;
1135}
1136
1137/*
1138 * When a child dies, we kill our entire process group with SIGTERM. This
1139 * also has the side effect that the shell restores the console for us!
1140 */
1141static void kill_launcher(int signal)
1142{
1143 kill(0, SIGTERM);
1144}
1145
1146static void reset_vq_pci_config(struct virtqueue *vq)
1147{
1148 vq->pci_config.queue_size = VIRTQUEUE_NUM;
1149 vq->pci_config.queue_enable = 0;
1150}
1151
1152static void reset_device(struct device *dev)
1153{
1154 struct virtqueue *vq;
1155
1156 verbose("Resetting device %s\n", dev->name);
1157
1158 /* Clear any features they've acked. */
1159 dev->features_accepted = 0;
1160
1161 /* We're going to be explicitly killing threads, so ignore them. */
1162 signal(SIGCHLD, SIG_IGN);
1163
1164 /*
1165 * 4.1.4.3.1:
1166 *
1167 * The device MUST present a 0 in queue_enable on reset.
1168 *
1169 * This means we set it here, and reset the saved ones in every vq.
1170 */
1171 dev->mmio->cfg.queue_enable = 0;
1172
1173 /* Get rid of the virtqueue threads */
1174 for (vq = dev->vq; vq; vq = vq->next) {
1175 vq->last_avail_idx = 0;
1176 reset_vq_pci_config(vq);
1177 if (vq->thread != (pid_t)-1) {
1178 kill(vq->thread, SIGTERM);
1179 waitpid(vq->thread, NULL, 0);
1180 vq->thread = (pid_t)-1;
1181 }
1182 }
1183 dev->running = false;
1184 dev->wrote_features_ok = false;
1185
1186 /* Now we care if threads die. */
1187 signal(SIGCHLD, (void *)kill_launcher);
1188}
1189
1190static void cleanup_devices(void)
1191{
1192 unsigned int i;
1193
1194 for (i = 1; i < MAX_PCI_DEVICES; i++) {
1195 struct device *d = devices.pci[i];
1196 if (!d)
1197 continue;
1198 reset_device(d);
1199 }
1200
1201 /* If we saved off the original terminal settings, restore them now. */
1202 if (orig_term.c_lflag & (ISIG|ICANON|ECHO))
1203 tcsetattr(STDIN_FILENO, TCSANOW, &orig_term);
1204}
1205
1206/*L:217
1207 * We do PCI. This is mainly done to let us test the kernel virtio PCI
1208 * code.
1209 */
1210
1211/* Linux expects a PCI host bridge: ours is a dummy, and first on the bus. */
1212static struct device pci_host_bridge;
1213
1214static void init_pci_host_bridge(void)
1215{
1216 pci_host_bridge.name = "PCI Host Bridge";
1217 pci_host_bridge.config.class = 0x06; /* bridge */
1218 pci_host_bridge.config.subclass = 0; /* host bridge */
1219 devices.pci[0] = &pci_host_bridge;
1220}
1221
1222/* The IO ports used to read the PCI config space. */
1223#define PCI_CONFIG_ADDR 0xCF8
1224#define PCI_CONFIG_DATA 0xCFC
1225
1226/*
1227 * Not really portable, but does help readability: this is what the Guest
1228 * writes to the PCI_CONFIG_ADDR IO port.
1229 */
1230union pci_config_addr {
1231 struct {
1232 unsigned mbz: 2;
1233 unsigned offset: 6;
1234 unsigned funcnum: 3;
1235 unsigned devnum: 5;
1236 unsigned busnum: 8;
1237 unsigned reserved: 7;
1238 unsigned enabled : 1;
1239 } bits;
1240 u32 val;
1241};
1242
1243/*
1244 * We cache what they wrote to the address port, so we know what they're
1245 * talking about when they access the data port.
1246 */
1247static union pci_config_addr pci_config_addr;
1248
1249static struct device *find_pci_device(unsigned int index)
1250{
1251 return devices.pci[index];
1252}
1253
1254/* PCI can do 1, 2 and 4 byte reads; we handle that here. */
1255static void ioread(u16 off, u32 v, u32 mask, u32 *val)
1256{
1257 assert(off < 4);
1258 assert(mask == 0xFF || mask == 0xFFFF || mask == 0xFFFFFFFF);
1259 *val = (v >> (off * 8)) & mask;
1260}
1261
1262/* PCI can do 1, 2 and 4 byte writes; we handle that here. */
1263static void iowrite(u16 off, u32 v, u32 mask, u32 *dst)
1264{
1265 assert(off < 4);
1266 assert(mask == 0xFF || mask == 0xFFFF || mask == 0xFFFFFFFF);
1267 *dst &= ~(mask << (off * 8));
1268 *dst |= (v & mask) << (off * 8);
1269}
1270
1271/*
1272 * Where PCI_CONFIG_DATA accesses depends on the previous write to
1273 * PCI_CONFIG_ADDR.
1274 */
1275static struct device *dev_and_reg(u32 *reg)
1276{
1277 if (!pci_config_addr.bits.enabled)
1278 return NULL;
1279
1280 if (pci_config_addr.bits.funcnum != 0)
1281 return NULL;
1282
1283 if (pci_config_addr.bits.busnum != 0)
1284 return NULL;
1285
1286 if (pci_config_addr.bits.offset * 4 >= sizeof(struct pci_config))
1287 return NULL;
1288
1289 *reg = pci_config_addr.bits.offset;
1290 return find_pci_device(pci_config_addr.bits.devnum);
1291}
1292
1293/*
1294 * We can get invalid combinations of values while they're writing, so we
1295 * only fault if they try to write with some invalid bar/offset/length.
1296 */
1297static bool valid_bar_access(struct device *d,
1298 struct virtio_pci_cfg_cap_u32 *cfg_access)
1299{
1300 /* We only have 1 bar (BAR0) */
1301 if (cfg_access->cap.bar != 0)
1302 return false;
1303
1304 /* Check it's within BAR0. */
1305 if (cfg_access->cap.offset >= d->mmio_size
1306 || cfg_access->cap.offset + cfg_access->cap.length > d->mmio_size)
1307 return false;
1308
1309 /* Check length is 1, 2 or 4. */
1310 if (cfg_access->cap.length != 1
1311 && cfg_access->cap.length != 2
1312 && cfg_access->cap.length != 4)
1313 return false;
1314
1315 /*
1316 * 4.1.4.7.2:
1317 *
1318 * The driver MUST NOT write a cap.offset which is not a multiple of
1319 * cap.length (ie. all accesses MUST be aligned).
1320 */
1321 if (cfg_access->cap.offset % cfg_access->cap.length != 0)
1322 return false;
1323
1324 /* Return pointer into word in BAR0. */
1325 return true;
1326}
1327
1328/* Is this accessing the PCI config address port?. */
1329static bool is_pci_addr_port(u16 port)
1330{
1331 return port >= PCI_CONFIG_ADDR && port < PCI_CONFIG_ADDR + 4;
1332}
1333
1334static bool pci_addr_iowrite(u16 port, u32 mask, u32 val)
1335{
1336 iowrite(port - PCI_CONFIG_ADDR, val, mask,
1337 &pci_config_addr.val);
1338 verbose("PCI%s: %#x/%x: bus %u dev %u func %u reg %u\n",
1339 pci_config_addr.bits.enabled ? "" : " DISABLED",
1340 val, mask,
1341 pci_config_addr.bits.busnum,
1342 pci_config_addr.bits.devnum,
1343 pci_config_addr.bits.funcnum,
1344 pci_config_addr.bits.offset);
1345 return true;
1346}
1347
1348static void pci_addr_ioread(u16 port, u32 mask, u32 *val)
1349{
1350 ioread(port - PCI_CONFIG_ADDR, pci_config_addr.val, mask, val);
1351}
1352
1353/* Is this accessing the PCI config data port?. */
1354static bool is_pci_data_port(u16 port)
1355{
1356 return port >= PCI_CONFIG_DATA && port < PCI_CONFIG_DATA + 4;
1357}
1358
1359static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask);
1360
1361static bool pci_data_iowrite(u16 port, u32 mask, u32 val)
1362{
1363 u32 reg, portoff;
1364 struct device *d = dev_and_reg(®);
1365
1366 /* Complain if they don't belong to a device. */
1367 if (!d)
1368 return false;
1369
1370 /* They can do 1 byte writes, etc. */
1371 portoff = port - PCI_CONFIG_DATA;
1372
1373 /*
1374 * PCI uses a weird way to determine the BAR size: the OS
1375 * writes all 1's, and sees which ones stick.
1376 */
1377 if (&d->config_words[reg] == &d->config.bar[0]) {
1378 int i;
1379
1380 iowrite(portoff, val, mask, &d->config.bar[0]);
1381 for (i = 0; (1 << i) < d->mmio_size; i++)
1382 d->config.bar[0] &= ~(1 << i);
1383 return true;
1384 } else if ((&d->config_words[reg] > &d->config.bar[0]
1385 && &d->config_words[reg] <= &d->config.bar[6])
1386 || &d->config_words[reg] == &d->config.expansion_rom_addr) {
1387 /* Allow writing to any other BAR, or expansion ROM */
1388 iowrite(portoff, val, mask, &d->config_words[reg]);
1389 return true;
1390 /* We let them overide latency timer and cacheline size */
1391 } else if (&d->config_words[reg] == (void *)&d->config.cacheline_size) {
1392 /* Only let them change the first two fields. */
1393 if (mask == 0xFFFFFFFF)
1394 mask = 0xFFFF;
1395 iowrite(portoff, val, mask, &d->config_words[reg]);
1396 return true;
1397 } else if (&d->config_words[reg] == (void *)&d->config.command
1398 && mask == 0xFFFF) {
1399 /* Ignore command writes. */
1400 return true;
1401 } else if (&d->config_words[reg]
1402 == (void *)&d->config.cfg_access.cap.bar
1403 || &d->config_words[reg]
1404 == &d->config.cfg_access.cap.length
1405 || &d->config_words[reg]
1406 == &d->config.cfg_access.cap.offset) {
1407
1408 /*
1409 * The VIRTIO_PCI_CAP_PCI_CFG capability
1410 * provides a backdoor to access the MMIO
1411 * regions without mapping them. Weird, but
1412 * useful.
1413 */
1414 iowrite(portoff, val, mask, &d->config_words[reg]);
1415 return true;
1416 } else if (&d->config_words[reg] == &d->config.cfg_access.pci_cfg_data) {
1417 u32 write_mask;
1418
1419 /*
1420 * 4.1.4.7.1:
1421 *
1422 * Upon detecting driver write access to pci_cfg_data, the
1423 * device MUST execute a write access at offset cap.offset at
1424 * BAR selected by cap.bar using the first cap.length bytes
1425 * from pci_cfg_data.
1426 */
1427
1428 /* Must be bar 0 */
1429 if (!valid_bar_access(d, &d->config.cfg_access))
1430 return false;
1431
1432 iowrite(portoff, val, mask, &d->config.cfg_access.pci_cfg_data);
1433
1434 /*
1435 * Now emulate a write. The mask we use is set by
1436 * len, *not* this write!
1437 */
1438 write_mask = (1ULL<<(8*d->config.cfg_access.cap.length)) - 1;
1439 verbose("Window writing %#x/%#x to bar %u, offset %u len %u\n",
1440 d->config.cfg_access.pci_cfg_data, write_mask,
1441 d->config.cfg_access.cap.bar,
1442 d->config.cfg_access.cap.offset,
1443 d->config.cfg_access.cap.length);
1444
1445 emulate_mmio_write(d, d->config.cfg_access.cap.offset,
1446 d->config.cfg_access.pci_cfg_data,
1447 write_mask);
1448 return true;
1449 }
1450
1451 /*
1452 * 4.1.4.1:
1453 *
1454 * The driver MUST NOT write into any field of the capability
1455 * structure, with the exception of those with cap_type
1456 * VIRTIO_PCI_CAP_PCI_CFG...
1457 */
1458 return false;
1459}
1460
1461static u32 emulate_mmio_read(struct device *d, u32 off, u32 mask);
1462
1463static void pci_data_ioread(u16 port, u32 mask, u32 *val)
1464{
1465 u32 reg;
1466 struct device *d = dev_and_reg(®);
1467
1468 if (!d)
1469 return;
1470
1471 /* Read through the PCI MMIO access window is special */
1472 if (&d->config_words[reg] == &d->config.cfg_access.pci_cfg_data) {
1473 u32 read_mask;
1474
1475 /*
1476 * 4.1.4.7.1:
1477 *
1478 * Upon detecting driver read access to pci_cfg_data, the
1479 * device MUST execute a read access of length cap.length at
1480 * offset cap.offset at BAR selected by cap.bar and store the
1481 * first cap.length bytes in pci_cfg_data.
1482 */
1483 /* Must be bar 0 */
1484 if (!valid_bar_access(d, &d->config.cfg_access))
1485 bad_driver(d,
1486 "Invalid cfg_access to bar%u, offset %u len %u",
1487 d->config.cfg_access.cap.bar,
1488 d->config.cfg_access.cap.offset,
1489 d->config.cfg_access.cap.length);
1490
1491 /*
1492 * Read into the window. The mask we use is set by
1493 * len, *not* this read!
1494 */
1495 read_mask = (1ULL<<(8*d->config.cfg_access.cap.length))-1;
1496 d->config.cfg_access.pci_cfg_data
1497 = emulate_mmio_read(d,
1498 d->config.cfg_access.cap.offset,
1499 read_mask);
1500 verbose("Window read %#x/%#x from bar %u, offset %u len %u\n",
1501 d->config.cfg_access.pci_cfg_data, read_mask,
1502 d->config.cfg_access.cap.bar,
1503 d->config.cfg_access.cap.offset,
1504 d->config.cfg_access.cap.length);
1505 }
1506 ioread(port - PCI_CONFIG_DATA, d->config_words[reg], mask, val);
1507}
1508
1509/*L:216
1510 * This is where we emulate a handful of Guest instructions. It's ugly
1511 * and we used to do it in the kernel but it grew over time.
1512 */
1513
1514/*
1515 * We use the ptrace syscall's pt_regs struct to talk about registers
1516 * to lguest: these macros convert the names to the offsets.
1517 */
1518#define getreg(name) getreg_off(offsetof(struct user_regs_struct, name))
1519#define setreg(name, val) \
1520 setreg_off(offsetof(struct user_regs_struct, name), (val))
1521
1522static u32 getreg_off(size_t offset)
1523{
1524 u32 r;
1525 unsigned long args[] = { LHREQ_GETREG, offset };
1526
1527 if (pwrite(lguest_fd, args, sizeof(args), cpu_id) < 0)
1528 err(1, "Getting register %u", offset);
1529 if (pread(lguest_fd, &r, sizeof(r), cpu_id) != sizeof(r))
1530 err(1, "Reading register %u", offset);
1531
1532 return r;
1533}
1534
1535static void setreg_off(size_t offset, u32 val)
1536{
1537 unsigned long args[] = { LHREQ_SETREG, offset, val };
1538
1539 if (pwrite(lguest_fd, args, sizeof(args), cpu_id) < 0)
1540 err(1, "Setting register %u", offset);
1541}
1542
1543/* Get register by instruction encoding */
1544static u32 getreg_num(unsigned regnum, u32 mask)
1545{
1546 /* 8 bit ops use regnums 4-7 for high parts of word */
1547 if (mask == 0xFF && (regnum & 0x4))
1548 return getreg_num(regnum & 0x3, 0xFFFF) >> 8;
1549
1550 switch (regnum) {
1551 case 0: return getreg(eax) & mask;
1552 case 1: return getreg(ecx) & mask;
1553 case 2: return getreg(edx) & mask;
1554 case 3: return getreg(ebx) & mask;
1555 case 4: return getreg(esp) & mask;
1556 case 5: return getreg(ebp) & mask;
1557 case 6: return getreg(esi) & mask;
1558 case 7: return getreg(edi) & mask;
1559 }
1560 abort();
1561}
1562
1563/* Set register by instruction encoding */
1564static void setreg_num(unsigned regnum, u32 val, u32 mask)
1565{
1566 /* Don't try to set bits out of range */
1567 assert(~(val & ~mask));
1568
1569 /* 8 bit ops use regnums 4-7 for high parts of word */
1570 if (mask == 0xFF && (regnum & 0x4)) {
1571 /* Construct the 16 bits we want. */
1572 val = (val << 8) | getreg_num(regnum & 0x3, 0xFF);
1573 setreg_num(regnum & 0x3, val, 0xFFFF);
1574 return;
1575 }
1576
1577 switch (regnum) {
1578 case 0: setreg(eax, val | (getreg(eax) & ~mask)); return;
1579 case 1: setreg(ecx, val | (getreg(ecx) & ~mask)); return;
1580 case 2: setreg(edx, val | (getreg(edx) & ~mask)); return;
1581 case 3: setreg(ebx, val | (getreg(ebx) & ~mask)); return;
1582 case 4: setreg(esp, val | (getreg(esp) & ~mask)); return;
1583 case 5: setreg(ebp, val | (getreg(ebp) & ~mask)); return;
1584 case 6: setreg(esi, val | (getreg(esi) & ~mask)); return;
1585 case 7: setreg(edi, val | (getreg(edi) & ~mask)); return;
1586 }
1587 abort();
1588}
1589
1590/* Get bytes of displacement appended to instruction, from r/m encoding */
1591static u32 insn_displacement_len(u8 mod_reg_rm)
1592{
1593 /* Switch on the mod bits */
1594 switch (mod_reg_rm >> 6) {
1595 case 0:
1596 /* If mod == 0, and r/m == 101, 16-bit displacement follows */
1597 if ((mod_reg_rm & 0x7) == 0x5)
1598 return 2;
1599 /* Normally, mod == 0 means no literal displacement */
1600 return 0;
1601 case 1:
1602 /* One byte displacement */
1603 return 1;
1604 case 2:
1605 /* Four byte displacement */
1606 return 4;
1607 case 3:
1608 /* Register mode */
1609 return 0;
1610 }
1611 abort();
1612}
1613
1614static void emulate_insn(const u8 insn[])
1615{
1616 unsigned long args[] = { LHREQ_TRAP, 13 };
1617 unsigned int insnlen = 0, in = 0, small_operand = 0, byte_access;
1618 unsigned int eax, port, mask;
1619 /*
1620 * Default is to return all-ones on IO port reads, which traditionally
1621 * means "there's nothing there".
1622 */
1623 u32 val = 0xFFFFFFFF;
1624
1625 /*
1626 * This must be the Guest kernel trying to do something, not userspace!
1627 * The bottom two bits of the CS segment register are the privilege
1628 * level.
1629 */
1630 if ((getreg(xcs) & 3) != 0x1)
1631 goto no_emulate;
1632
1633 /* Decoding x86 instructions is icky. */
1634
1635 /*
1636 * Around 2.6.33, the kernel started using an emulation for the
1637 * cmpxchg8b instruction in early boot on many configurations. This
1638 * code isn't paravirtualized, and it tries to disable interrupts.
1639 * Ignore it, which will Mostly Work.
1640 */
1641 if (insn[insnlen] == 0xfa) {
1642 /* "cli", or Clear Interrupt Enable instruction. Skip it. */
1643 insnlen = 1;
1644 goto skip_insn;
1645 }
1646
1647 /*
1648 * 0x66 is an "operand prefix". It means a 16, not 32 bit in/out.
1649 */
1650 if (insn[insnlen] == 0x66) {
1651 small_operand = 1;
1652 /* The instruction is 1 byte so far, read the next byte. */
1653 insnlen = 1;
1654 }
1655
1656 /* If the lower bit isn't set, it's a single byte access */
1657 byte_access = !(insn[insnlen] & 1);
1658
1659 /*
1660 * Now we can ignore the lower bit and decode the 4 opcodes
1661 * we need to emulate.
1662 */
1663 switch (insn[insnlen] & 0xFE) {
1664 case 0xE4: /* in <next byte>,%al */
1665 port = insn[insnlen+1];
1666 insnlen += 2;
1667 in = 1;
1668 break;
1669 case 0xEC: /* in (%dx),%al */
1670 port = getreg(edx) & 0xFFFF;
1671 insnlen += 1;
1672 in = 1;
1673 break;
1674 case 0xE6: /* out %al,<next byte> */
1675 port = insn[insnlen+1];
1676 insnlen += 2;
1677 break;
1678 case 0xEE: /* out %al,(%dx) */
1679 port = getreg(edx) & 0xFFFF;
1680 insnlen += 1;
1681 break;
1682 default:
1683 /* OK, we don't know what this is, can't emulate. */
1684 goto no_emulate;
1685 }
1686
1687 /* Set a mask of the 1, 2 or 4 bytes, depending on size of IO */
1688 if (byte_access)
1689 mask = 0xFF;
1690 else if (small_operand)
1691 mask = 0xFFFF;
1692 else
1693 mask = 0xFFFFFFFF;
1694
1695 /*
1696 * If it was an "IN" instruction, they expect the result to be read
1697 * into %eax, so we change %eax.
1698 */
1699 eax = getreg(eax);
1700
1701 if (in) {
1702 /* This is the PS/2 keyboard status; 1 means ready for output */
1703 if (port == 0x64)
1704 val = 1;
1705 else if (is_pci_addr_port(port))
1706 pci_addr_ioread(port, mask, &val);
1707 else if (is_pci_data_port(port))
1708 pci_data_ioread(port, mask, &val);
1709
1710 /* Clear the bits we're about to read */
1711 eax &= ~mask;
1712 /* Copy bits in from val. */
1713 eax |= val & mask;
1714 /* Now update the register. */
1715 setreg(eax, eax);
1716 } else {
1717 if (is_pci_addr_port(port)) {
1718 if (!pci_addr_iowrite(port, mask, eax))
1719 goto bad_io;
1720 } else if (is_pci_data_port(port)) {
1721 if (!pci_data_iowrite(port, mask, eax))
1722 goto bad_io;
1723 }
1724 /* There are many other ports, eg. CMOS clock, serial
1725 * and parallel ports, so we ignore them all. */
1726 }
1727
1728 verbose("IO %s of %x to %u: %#08x\n",
1729 in ? "IN" : "OUT", mask, port, eax);
1730skip_insn:
1731 /* Finally, we've "done" the instruction, so move past it. */
1732 setreg(eip, getreg(eip) + insnlen);
1733 return;
1734
1735bad_io:
1736 warnx("Attempt to %s port %u (%#x mask)",
1737 in ? "read from" : "write to", port, mask);
1738
1739no_emulate:
1740 /* Inject trap into Guest. */
1741 if (write(lguest_fd, args, sizeof(args)) < 0)
1742 err(1, "Reinjecting trap 13 for fault at %#x", getreg(eip));
1743}
1744
1745static struct device *find_mmio_region(unsigned long paddr, u32 *off)
1746{
1747 unsigned int i;
1748
1749 for (i = 1; i < MAX_PCI_DEVICES; i++) {
1750 struct device *d = devices.pci[i];
1751
1752 if (!d)
1753 continue;
1754 if (paddr < d->mmio_addr)
1755 continue;
1756 if (paddr >= d->mmio_addr + d->mmio_size)
1757 continue;
1758 *off = paddr - d->mmio_addr;
1759 return d;
1760 }
1761 return NULL;
1762}
1763
1764/* FIXME: Use vq array. */
1765static struct virtqueue *vq_by_num(struct device *d, u32 num)
1766{
1767 struct virtqueue *vq = d->vq;
1768
1769 while (num-- && vq)
1770 vq = vq->next;
1771
1772 return vq;
1773}
1774
1775static void save_vq_config(const struct virtio_pci_common_cfg *cfg,
1776 struct virtqueue *vq)
1777{
1778 vq->pci_config = *cfg;
1779}
1780
1781static void restore_vq_config(struct virtio_pci_common_cfg *cfg,
1782 struct virtqueue *vq)
1783{
1784 /* Only restore the per-vq part */
1785 size_t off = offsetof(struct virtio_pci_common_cfg, queue_size);
1786
1787 memcpy((void *)cfg + off, (void *)&vq->pci_config + off,
1788 sizeof(*cfg) - off);
1789}
1790
1791/*
1792 * 4.1.4.3.2:
1793 *
1794 * The driver MUST configure the other virtqueue fields before
1795 * enabling the virtqueue with queue_enable.
1796 *
1797 * When they enable the virtqueue, we check that their setup is valid.
1798 */
1799static void check_virtqueue(struct device *d, struct virtqueue *vq)
1800{
1801 /* Because lguest is 32 bit, all the descriptor high bits must be 0 */
1802 if (vq->pci_config.queue_desc_hi
1803 || vq->pci_config.queue_avail_hi
1804 || vq->pci_config.queue_used_hi)
1805 bad_driver_vq(vq, "invalid 64-bit queue address");
1806
1807 /*
1808 * 2.4.1:
1809 *
1810 * The driver MUST ensure that the physical address of the first byte
1811 * of each virtqueue part is a multiple of the specified alignment
1812 * value in the above table.
1813 */
1814 if (vq->pci_config.queue_desc_lo % 16
1815 || vq->pci_config.queue_avail_lo % 2
1816 || vq->pci_config.queue_used_lo % 4)
1817 bad_driver_vq(vq, "invalid alignment in queue addresses");
1818
1819 /* Initialize the virtqueue and check they're all in range. */
1820 vq->vring.num = vq->pci_config.queue_size;
1821 vq->vring.desc = check_pointer(vq->dev,
1822 vq->pci_config.queue_desc_lo,
1823 sizeof(*vq->vring.desc) * vq->vring.num);
1824 vq->vring.avail = check_pointer(vq->dev,
1825 vq->pci_config.queue_avail_lo,
1826 sizeof(*vq->vring.avail)
1827 + (sizeof(vq->vring.avail->ring[0])
1828 * vq->vring.num));
1829 vq->vring.used = check_pointer(vq->dev,
1830 vq->pci_config.queue_used_lo,
1831 sizeof(*vq->vring.used)
1832 + (sizeof(vq->vring.used->ring[0])
1833 * vq->vring.num));
1834
1835 /*
1836 * 2.4.9.1:
1837 *
1838 * The driver MUST initialize flags in the used ring to 0
1839 * when allocating the used ring.
1840 */
1841 if (vq->vring.used->flags != 0)
1842 bad_driver_vq(vq, "invalid initial used.flags %#x",
1843 vq->vring.used->flags);
1844}
1845
1846static void start_virtqueue(struct virtqueue *vq)
1847{
1848 /*
1849 * Create stack for thread. Since the stack grows upwards, we point
1850 * the stack pointer to the end of this region.
1851 */
1852 char *stack = malloc(32768);
1853
1854 /* Create a zero-initialized eventfd. */
1855 vq->eventfd = eventfd(0, 0);
1856 if (vq->eventfd < 0)
1857 err(1, "Creating eventfd");
1858
1859 /*
1860 * CLONE_VM: because it has to access the Guest memory, and SIGCHLD so
1861 * we get a signal if it dies.
1862 */
1863 vq->thread = clone(do_thread, stack + 32768, CLONE_VM | SIGCHLD, vq);
1864 if (vq->thread == (pid_t)-1)
1865 err(1, "Creating clone");
1866}
1867
1868static void start_virtqueues(struct device *d)
1869{
1870 struct virtqueue *vq;
1871
1872 for (vq = d->vq; vq; vq = vq->next) {
1873 if (vq->pci_config.queue_enable)
1874 start_virtqueue(vq);
1875 }
1876}
1877
1878static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask)
1879{
1880 struct virtqueue *vq;
1881
1882 switch (off) {
1883 case offsetof(struct virtio_pci_mmio, cfg.device_feature_select):
1884 /*
1885 * 4.1.4.3.1:
1886 *
1887 * The device MUST present the feature bits it is offering in
1888 * device_feature, starting at bit device_feature_select ∗ 32
1889 * for any device_feature_select written by the driver
1890 */
1891 if (val == 0)
1892 d->mmio->cfg.device_feature = d->features;
1893 else if (val == 1)
1894 d->mmio->cfg.device_feature = (d->features >> 32);
1895 else
1896 d->mmio->cfg.device_feature = 0;
1897 goto feature_write_through32;
1898 case offsetof(struct virtio_pci_mmio, cfg.guest_feature_select):
1899 if (val > 1)
1900 bad_driver(d, "Unexpected driver select %u", val);
1901 goto feature_write_through32;
1902 case offsetof(struct virtio_pci_mmio, cfg.guest_feature):
1903 if (d->mmio->cfg.guest_feature_select == 0) {
1904 d->features_accepted &= ~((u64)0xFFFFFFFF);
1905 d->features_accepted |= val;
1906 } else {
1907 assert(d->mmio->cfg.guest_feature_select == 1);
1908 d->features_accepted &= 0xFFFFFFFF;
1909 d->features_accepted |= ((u64)val) << 32;
1910 }
1911 /*
1912 * 2.2.1:
1913 *
1914 * The driver MUST NOT accept a feature which the device did
1915 * not offer
1916 */
1917 if (d->features_accepted & ~d->features)
1918 bad_driver(d, "over-accepted features %#llx of %#llx",
1919 d->features_accepted, d->features);
1920 goto feature_write_through32;
1921 case offsetof(struct virtio_pci_mmio, cfg.device_status): {
1922 u8 prev;
1923
1924 verbose("%s: device status -> %#x\n", d->name, val);
1925 /*
1926 * 4.1.4.3.1:
1927 *
1928 * The device MUST reset when 0 is written to device_status,
1929 * and present a 0 in device_status once that is done.
1930 */
1931 if (val == 0) {
1932 reset_device(d);
1933 goto write_through8;
1934 }
1935
1936 /* 2.1.1: The driver MUST NOT clear a device status bit. */
1937 if (d->mmio->cfg.device_status & ~val)
1938 bad_driver(d, "unset of device status bit %#x -> %#x",
1939 d->mmio->cfg.device_status, val);
1940
1941 /*
1942 * 2.1.2:
1943 *
1944 * The device MUST NOT consume buffers or notify the driver
1945 * before DRIVER_OK.
1946 */
1947 if (val & VIRTIO_CONFIG_S_DRIVER_OK
1948 && !(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER_OK))
1949 start_virtqueues(d);
1950
1951 /*
1952 * 3.1.1:
1953 *
1954 * The driver MUST follow this sequence to initialize a device:
1955 * - Reset the device.
1956 * - Set the ACKNOWLEDGE status bit: the guest OS has
1957 * notice the device.
1958 * - Set the DRIVER status bit: the guest OS knows how
1959 * to drive the device.
1960 * - Read device feature bits, and write the subset
1961 * of feature bits understood by the OS and driver
1962 * to the device. During this step the driver MAY
1963 * read (but MUST NOT write) the device-specific
1964 * configuration fields to check that it can
1965 * support the device before accepting it.
1966 * - Set the FEATURES_OK status bit. The driver
1967 * MUST not accept new feature bits after this
1968 * step.
1969 * - Re-read device status to ensure the FEATURES_OK
1970 * bit is still set: otherwise, the device does
1971 * not support our subset of features and the
1972 * device is unusable.
1973 * - Perform device-specific setup, including
1974 * discovery of virtqueues for the device,
1975 * optional per-bus setup, reading and possibly
1976 * writing the device’s virtio configuration
1977 * space, and population of virtqueues.
1978 * - Set the DRIVER_OK status bit. At this point the
1979 * device is “live”.
1980 */
1981 prev = 0;
1982 switch (val & ~d->mmio->cfg.device_status) {
1983 case VIRTIO_CONFIG_S_DRIVER_OK:
1984 prev |= VIRTIO_CONFIG_S_FEATURES_OK; /* fall thru */
1985 case VIRTIO_CONFIG_S_FEATURES_OK:
1986 prev |= VIRTIO_CONFIG_S_DRIVER; /* fall thru */
1987 case VIRTIO_CONFIG_S_DRIVER:
1988 prev |= VIRTIO_CONFIG_S_ACKNOWLEDGE; /* fall thru */
1989 case VIRTIO_CONFIG_S_ACKNOWLEDGE:
1990 break;
1991 default:
1992 bad_driver(d, "unknown device status bit %#x -> %#x",
1993 d->mmio->cfg.device_status, val);
1994 }
1995 if (d->mmio->cfg.device_status != prev)
1996 bad_driver(d, "unexpected status transition %#x -> %#x",
1997 d->mmio->cfg.device_status, val);
1998
1999 /* If they just wrote FEATURES_OK, we make sure they read */
2000 switch (val & ~d->mmio->cfg.device_status) {
2001 case VIRTIO_CONFIG_S_FEATURES_OK:
2002 d->wrote_features_ok = true;
2003 break;
2004 case VIRTIO_CONFIG_S_DRIVER_OK:
2005 if (d->wrote_features_ok)
2006 bad_driver(d, "did not re-read FEATURES_OK");
2007 break;
2008 }
2009 goto write_through8;
2010 }
2011 case offsetof(struct virtio_pci_mmio, cfg.queue_select):
2012 vq = vq_by_num(d, val);
2013 /*
2014 * 4.1.4.3.1:
2015 *
2016 * The device MUST present a 0 in queue_size if the virtqueue
2017 * corresponding to the current queue_select is unavailable.
2018 */
2019 if (!vq) {
2020 d->mmio->cfg.queue_size = 0;
2021 goto write_through16;
2022 }
2023 /* Save registers for old vq, if it was a valid vq */
2024 if (d->mmio->cfg.queue_size)
2025 save_vq_config(&d->mmio->cfg,
2026 vq_by_num(d, d->mmio->cfg.queue_select));
2027 /* Restore the registers for the queue they asked for */
2028 restore_vq_config(&d->mmio->cfg, vq);
2029 goto write_through16;
2030 case offsetof(struct virtio_pci_mmio, cfg.queue_size):
2031 /*
2032 * 4.1.4.3.2:
2033 *
2034 * The driver MUST NOT write a value which is not a power of 2
2035 * to queue_size.
2036 */
2037 if (val & (val-1))
2038 bad_driver(d, "invalid queue size %u", val);
2039 if (d->mmio->cfg.queue_enable)
2040 bad_driver(d, "changing queue size on live device");
2041 goto write_through16;
2042 case offsetof(struct virtio_pci_mmio, cfg.queue_msix_vector):
2043 bad_driver(d, "attempt to set MSIX vector to %u", val);
2044 case offsetof(struct virtio_pci_mmio, cfg.queue_enable): {
2045 struct virtqueue *vq = vq_by_num(d, d->mmio->cfg.queue_select);
2046
2047 /*
2048 * 4.1.4.3.2:
2049 *
2050 * The driver MUST NOT write a 0 to queue_enable.
2051 */
2052 if (val != 1)
2053 bad_driver(d, "setting queue_enable to %u", val);
2054
2055 /*
2056 * 3.1.1:
2057 *
2058 * 7. Perform device-specific setup, including discovery of
2059 * virtqueues for the device, optional per-bus setup,
2060 * reading and possibly writing the device’s virtio
2061 * configuration space, and population of virtqueues.
2062 * 8. Set the DRIVER_OK status bit.
2063 *
2064 * All our devices require all virtqueues to be enabled, so
2065 * they should have done that before setting DRIVER_OK.
2066 */
2067 if (d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER_OK)
2068 bad_driver(d, "enabling vq after DRIVER_OK");
2069
2070 d->mmio->cfg.queue_enable = val;
2071 save_vq_config(&d->mmio->cfg, vq);
2072 check_virtqueue(d, vq);
2073 goto write_through16;
2074 }
2075 case offsetof(struct virtio_pci_mmio, cfg.queue_notify_off):
2076 bad_driver(d, "attempt to write to queue_notify_off");
2077 case offsetof(struct virtio_pci_mmio, cfg.queue_desc_lo):
2078 case offsetof(struct virtio_pci_mmio, cfg.queue_desc_hi):
2079 case offsetof(struct virtio_pci_mmio, cfg.queue_avail_lo):
2080 case offsetof(struct virtio_pci_mmio, cfg.queue_avail_hi):
2081 case offsetof(struct virtio_pci_mmio, cfg.queue_used_lo):
2082 case offsetof(struct virtio_pci_mmio, cfg.queue_used_hi):
2083 /*
2084 * 4.1.4.3.2:
2085 *
2086 * The driver MUST configure the other virtqueue fields before
2087 * enabling the virtqueue with queue_enable.
2088 */
2089 if (d->mmio->cfg.queue_enable)
2090 bad_driver(d, "changing queue on live device");
2091
2092 /*
2093 * 3.1.1:
2094 *
2095 * The driver MUST follow this sequence to initialize a device:
2096 *...
2097 * 5. Set the FEATURES_OK status bit. The driver MUST not
2098 * accept new feature bits after this step.
2099 */
2100 if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_FEATURES_OK))
2101 bad_driver(d, "setting up vq before FEATURES_OK");
2102
2103 /*
2104 * 6. Re-read device status to ensure the FEATURES_OK bit is
2105 * still set...
2106 */
2107 if (d->wrote_features_ok)
2108 bad_driver(d, "didn't re-read FEATURES_OK before setup");
2109
2110 goto write_through32;
2111 case offsetof(struct virtio_pci_mmio, notify):
2112 vq = vq_by_num(d, val);
2113 if (!vq)
2114 bad_driver(d, "Invalid vq notification on %u", val);
2115 /* Notify the process handling this vq by adding 1 to eventfd */
2116 write(vq->eventfd, "\1\0\0\0\0\0\0\0", 8);
2117 goto write_through16;
2118 case offsetof(struct virtio_pci_mmio, isr):
2119 bad_driver(d, "Unexpected write to isr");
2120 /* Weird corner case: write to emerg_wr of console */
2121 case sizeof(struct virtio_pci_mmio)
2122 + offsetof(struct virtio_console_config, emerg_wr):
2123 if (strcmp(d->name, "console") == 0) {
2124 char c = val;
2125 write(STDOUT_FILENO, &c, 1);
2126 goto write_through32;
2127 }
2128 /* Fall through... */
2129 default:
2130 /*
2131 * 4.1.4.3.2:
2132 *
2133 * The driver MUST NOT write to device_feature, num_queues,
2134 * config_generation or queue_notify_off.
2135 */
2136 bad_driver(d, "Unexpected write to offset %u", off);
2137 }
2138
2139feature_write_through32:
2140 /*
2141 * 3.1.1:
2142 *
2143 * The driver MUST follow this sequence to initialize a device:
2144 *...
2145 * - Set the DRIVER status bit: the guest OS knows how
2146 * to drive the device.
2147 * - Read device feature bits, and write the subset
2148 * of feature bits understood by the OS and driver
2149 * to the device.
2150 *...
2151 * - Set the FEATURES_OK status bit. The driver MUST not
2152 * accept new feature bits after this step.
2153 */
2154 if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER))
2155 bad_driver(d, "feature write before VIRTIO_CONFIG_S_DRIVER");
2156 if (d->mmio->cfg.device_status & VIRTIO_CONFIG_S_FEATURES_OK)
2157 bad_driver(d, "feature write after VIRTIO_CONFIG_S_FEATURES_OK");
2158
2159 /*
2160 * 4.1.3.1:
2161 *
2162 * The driver MUST access each field using the “natural” access
2163 * method, i.e. 32-bit accesses for 32-bit fields, 16-bit accesses for
2164 * 16-bit fields and 8-bit accesses for 8-bit fields.
2165 */
2166write_through32:
2167 if (mask != 0xFFFFFFFF) {
2168 bad_driver(d, "non-32-bit write to offset %u (%#x)",
2169 off, getreg(eip));
2170 return;
2171 }
2172 memcpy((char *)d->mmio + off, &val, 4);
2173 return;
2174
2175write_through16:
2176 if (mask != 0xFFFF)
2177 bad_driver(d, "non-16-bit write to offset %u (%#x)",
2178 off, getreg(eip));
2179 memcpy((char *)d->mmio + off, &val, 2);
2180 return;
2181
2182write_through8:
2183 if (mask != 0xFF)
2184 bad_driver(d, "non-8-bit write to offset %u (%#x)",
2185 off, getreg(eip));
2186 memcpy((char *)d->mmio + off, &val, 1);
2187 return;
2188}
2189
2190static u32 emulate_mmio_read(struct device *d, u32 off, u32 mask)
2191{
2192 u8 isr;
2193 u32 val = 0;
2194
2195 switch (off) {
2196 case offsetof(struct virtio_pci_mmio, cfg.device_feature_select):
2197 case offsetof(struct virtio_pci_mmio, cfg.device_feature):
2198 case offsetof(struct virtio_pci_mmio, cfg.guest_feature_select):
2199 case offsetof(struct virtio_pci_mmio, cfg.guest_feature):
2200 /*
2201 * 3.1.1:
2202 *
2203 * The driver MUST follow this sequence to initialize a device:
2204 *...
2205 * - Set the DRIVER status bit: the guest OS knows how
2206 * to drive the device.
2207 * - Read device feature bits, and write the subset
2208 * of feature bits understood by the OS and driver
2209 * to the device.
2210 */
2211 if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER))
2212 bad_driver(d,
2213 "feature read before VIRTIO_CONFIG_S_DRIVER");
2214 goto read_through32;
2215 case offsetof(struct virtio_pci_mmio, cfg.msix_config):
2216 bad_driver(d, "read of msix_config");
2217 case offsetof(struct virtio_pci_mmio, cfg.num_queues):
2218 goto read_through16;
2219 case offsetof(struct virtio_pci_mmio, cfg.device_status):
2220 /* As they did read, any write of FEATURES_OK is now fine. */
2221 d->wrote_features_ok = false;
2222 goto read_through8;
2223 case offsetof(struct virtio_pci_mmio, cfg.config_generation):
2224 /*
2225 * 4.1.4.3.1:
2226 *
2227 * The device MUST present a changed config_generation after
2228 * the driver has read a device-specific configuration value
2229 * which has changed since any part of the device-specific
2230 * configuration was last read.
2231 *
2232 * This is simple: none of our devices change config, so this
2233 * is always 0.
2234 */
2235 goto read_through8;
2236 case offsetof(struct virtio_pci_mmio, notify):
2237 /*
2238 * 3.1.1:
2239 *
2240 * The driver MUST NOT notify the device before setting
2241 * DRIVER_OK.
2242 */
2243 if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER_OK))
2244 bad_driver(d, "notify before VIRTIO_CONFIG_S_DRIVER_OK");
2245 goto read_through16;
2246 case offsetof(struct virtio_pci_mmio, isr):
2247 if (mask != 0xFF)
2248 bad_driver(d, "non-8-bit read from offset %u (%#x)",
2249 off, getreg(eip));
2250 isr = d->mmio->isr;
2251 /*
2252 * 4.1.4.5.1:
2253 *
2254 * The device MUST reset ISR status to 0 on driver read.
2255 */
2256 d->mmio->isr = 0;
2257 return isr;
2258 case offsetof(struct virtio_pci_mmio, padding):
2259 bad_driver(d, "read from padding (%#x)", getreg(eip));
2260 default:
2261 /* Read from device config space, beware unaligned overflow */
2262 if (off > d->mmio_size - 4)
2263 bad_driver(d, "read past end (%#x)", getreg(eip));
2264
2265 /*
2266 * 3.1.1:
2267 * The driver MUST follow this sequence to initialize a device:
2268 *...
2269 * 3. Set the DRIVER status bit: the guest OS knows how to
2270 * drive the device.
2271 * 4. Read device feature bits, and write the subset of
2272 * feature bits understood by the OS and driver to the
2273 * device. During this step the driver MAY read (but MUST NOT
2274 * write) the device-specific configuration fields to check
2275 * that it can support the device before accepting it.
2276 */
2277 if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER))
2278 bad_driver(d,
2279 "config read before VIRTIO_CONFIG_S_DRIVER");
2280
2281 if (mask == 0xFFFFFFFF)
2282 goto read_through32;
2283 else if (mask == 0xFFFF)
2284 goto read_through16;
2285 else
2286 goto read_through8;
2287 }
2288
2289 /*
2290 * 4.1.3.1:
2291 *
2292 * The driver MUST access each field using the “natural” access
2293 * method, i.e. 32-bit accesses for 32-bit fields, 16-bit accesses for
2294 * 16-bit fields and 8-bit accesses for 8-bit fields.
2295 */
2296read_through32:
2297 if (mask != 0xFFFFFFFF)
2298 bad_driver(d, "non-32-bit read to offset %u (%#x)",
2299 off, getreg(eip));
2300 memcpy(&val, (char *)d->mmio + off, 4);
2301 return val;
2302
2303read_through16:
2304 if (mask != 0xFFFF)
2305 bad_driver(d, "non-16-bit read to offset %u (%#x)",
2306 off, getreg(eip));
2307 memcpy(&val, (char *)d->mmio + off, 2);
2308 return val;
2309
2310read_through8:
2311 if (mask != 0xFF)
2312 bad_driver(d, "non-8-bit read to offset %u (%#x)",
2313 off, getreg(eip));
2314 memcpy(&val, (char *)d->mmio + off, 1);
2315 return val;
2316}
2317
2318static void emulate_mmio(unsigned long paddr, const u8 *insn)
2319{
2320 u32 val, off, mask = 0xFFFFFFFF, insnlen = 0;
2321 struct device *d = find_mmio_region(paddr, &off);
2322 unsigned long args[] = { LHREQ_TRAP, 14 };
2323
2324 if (!d) {
2325 warnx("MMIO touching %#08lx (not a device)", paddr);
2326 goto reinject;
2327 }
2328
2329 /* Prefix makes it a 16 bit op */
2330 if (insn[0] == 0x66) {
2331 mask = 0xFFFF;
2332 insnlen++;
2333 }
2334
2335 /* iowrite */
2336 if (insn[insnlen] == 0x89) {
2337 /* Next byte is r/m byte: bits 3-5 are register. */
2338 val = getreg_num((insn[insnlen+1] >> 3) & 0x7, mask);
2339 emulate_mmio_write(d, off, val, mask);
2340 insnlen += 2 + insn_displacement_len(insn[insnlen+1]);
2341 } else if (insn[insnlen] == 0x8b) { /* ioread */
2342 /* Next byte is r/m byte: bits 3-5 are register. */
2343 val = emulate_mmio_read(d, off, mask);
2344 setreg_num((insn[insnlen+1] >> 3) & 0x7, val, mask);
2345 insnlen += 2 + insn_displacement_len(insn[insnlen+1]);
2346 } else if (insn[0] == 0x88) { /* 8-bit iowrite */
2347 mask = 0xff;
2348 /* Next byte is r/m byte: bits 3-5 are register. */
2349 val = getreg_num((insn[1] >> 3) & 0x7, mask);
2350 emulate_mmio_write(d, off, val, mask);
2351 insnlen = 2 + insn_displacement_len(insn[1]);
2352 } else if (insn[0] == 0x8a) { /* 8-bit ioread */
2353 mask = 0xff;
2354 val = emulate_mmio_read(d, off, mask);
2355 setreg_num((insn[1] >> 3) & 0x7, val, mask);
2356 insnlen = 2 + insn_displacement_len(insn[1]);
2357 } else {
2358 warnx("Unknown MMIO instruction touching %#08lx:"
2359 " %02x %02x %02x %02x at %u",
2360 paddr, insn[0], insn[1], insn[2], insn[3], getreg(eip));
2361 reinject:
2362 /* Inject trap into Guest. */
2363 if (write(lguest_fd, args, sizeof(args)) < 0)
2364 err(1, "Reinjecting trap 14 for fault at %#x",
2365 getreg(eip));
2366 return;
2367 }
2368
2369 /* Finally, we've "done" the instruction, so move past it. */
2370 setreg(eip, getreg(eip) + insnlen);
2371}
2372
2373/*L:190
2374 * Device Setup
2375 *
2376 * All devices need a descriptor so the Guest knows it exists, and a "struct
2377 * device" so the Launcher can keep track of it. We have common helper
2378 * routines to allocate and manage them.
2379 */
2380static void add_pci_virtqueue(struct device *dev,
2381 void (*service)(struct virtqueue *),
2382 const char *name)
2383{
2384 struct virtqueue **i, *vq = malloc(sizeof(*vq));
2385
2386 /* Initialize the virtqueue */
2387 vq->next = NULL;
2388 vq->last_avail_idx = 0;
2389 vq->dev = dev;
2390 vq->name = name;
2391
2392 /*
2393 * This is the routine the service thread will run, and its Process ID
2394 * once it's running.
2395 */
2396 vq->service = service;
2397 vq->thread = (pid_t)-1;
2398
2399 /* Initialize the configuration. */
2400 reset_vq_pci_config(vq);
2401 vq->pci_config.queue_notify_off = 0;
2402
2403 /* Add one to the number of queues */
2404 vq->dev->mmio->cfg.num_queues++;
2405
2406 /*
2407 * Add to tail of list, so dev->vq is first vq, dev->vq->next is
2408 * second.
2409 */
2410 for (i = &dev->vq; *i; i = &(*i)->next);
2411 *i = vq;
2412}
2413
2414/* The Guest accesses the feature bits via the PCI common config MMIO region */
2415static void add_pci_feature(struct device *dev, unsigned bit)
2416{
2417 dev->features |= (1ULL << bit);
2418}
2419
2420/* For devices with no config. */
2421static void no_device_config(struct device *dev)
2422{
2423 dev->mmio_addr = get_mmio_region(dev->mmio_size);
2424
2425 dev->config.bar[0] = dev->mmio_addr;
2426 /* Bottom 4 bits must be zero */
2427 assert(~(dev->config.bar[0] & 0xF));
2428}
2429
2430/* This puts the device config into BAR0 */
2431static void set_device_config(struct device *dev, const void *conf, size_t len)
2432{
2433 /* Set up BAR 0 */
2434 dev->mmio_size += len;
2435 dev->mmio = realloc(dev->mmio, dev->mmio_size);
2436 memcpy(dev->mmio + 1, conf, len);
2437
2438 /*
2439 * 4.1.4.6:
2440 *
2441 * The device MUST present at least one VIRTIO_PCI_CAP_DEVICE_CFG
2442 * capability for any device type which has a device-specific
2443 * configuration.
2444 */
2445 /* Hook up device cfg */
2446 dev->config.cfg_access.cap.cap_next
2447 = offsetof(struct pci_config, device);
2448
2449 /*
2450 * 4.1.4.6.1:
2451 *
2452 * The offset for the device-specific configuration MUST be 4-byte
2453 * aligned.
2454 */
2455 assert(dev->config.cfg_access.cap.cap_next % 4 == 0);
2456
2457 /* Fix up device cfg field length. */
2458 dev->config.device.length = len;
2459
2460 /* The rest is the same as the no-config case */
2461 no_device_config(dev);
2462}
2463
2464static void init_cap(struct virtio_pci_cap *cap, size_t caplen, int type,
2465 size_t bar_offset, size_t bar_bytes, u8 next)
2466{
2467 cap->cap_vndr = PCI_CAP_ID_VNDR;
2468 cap->cap_next = next;
2469 cap->cap_len = caplen;
2470 cap->cfg_type = type;
2471 cap->bar = 0;
2472 memset(cap->padding, 0, sizeof(cap->padding));
2473 cap->offset = bar_offset;
2474 cap->length = bar_bytes;
2475}
2476
2477/*
2478 * This sets up the pci_config structure, as defined in the virtio 1.0
2479 * standard (and PCI standard).
2480 */
2481static void init_pci_config(struct pci_config *pci, u16 type,
2482 u8 class, u8 subclass)
2483{
2484 size_t bar_offset, bar_len;
2485
2486 /*
2487 * 4.1.4.4.1:
2488 *
2489 * The device MUST either present notify_off_multiplier as an even
2490 * power of 2, or present notify_off_multiplier as 0.
2491 *
2492 * 2.1.2:
2493 *
2494 * The device MUST initialize device status to 0 upon reset.
2495 */
2496 memset(pci, 0, sizeof(*pci));
2497
2498 /* 4.1.2.1: Devices MUST have the PCI Vendor ID 0x1AF4 */
2499 pci->vendor_id = 0x1AF4;
2500 /* 4.1.2.1: ... PCI Device ID calculated by adding 0x1040 ... */
2501 pci->device_id = 0x1040 + type;
2502
2503 /*
2504 * PCI have specific codes for different types of devices.
2505 * Linux doesn't care, but it's a good clue for people looking
2506 * at the device.
2507 */
2508 pci->class = class;
2509 pci->subclass = subclass;
2510
2511 /*
2512 * 4.1.2.1:
2513 *
2514 * Non-transitional devices SHOULD have a PCI Revision ID of 1 or
2515 * higher
2516 */
2517 pci->revid = 1;
2518
2519 /*
2520 * 4.1.2.1:
2521 *
2522 * Non-transitional devices SHOULD have a PCI Subsystem Device ID of
2523 * 0x40 or higher.
2524 */
2525 pci->subsystem_device_id = 0x40;
2526
2527 /* We use our dummy interrupt controller, and irq_line is the irq */
2528 pci->irq_line = devices.next_irq++;
2529 pci->irq_pin = 0;
2530
2531 /* Support for extended capabilities. */
2532 pci->status = (1 << 4);
2533
2534 /* Link them in. */
2535 /*
2536 * 4.1.4.3.1:
2537 *
2538 * The device MUST present at least one common configuration
2539 * capability.
2540 */
2541 pci->capabilities = offsetof(struct pci_config, common);
2542
2543 /* 4.1.4.3.1 ... offset MUST be 4-byte aligned. */
2544 assert(pci->capabilities % 4 == 0);
2545
2546 bar_offset = offsetof(struct virtio_pci_mmio, cfg);
2547 bar_len = sizeof(((struct virtio_pci_mmio *)0)->cfg);
2548 init_cap(&pci->common, sizeof(pci->common), VIRTIO_PCI_CAP_COMMON_CFG,
2549 bar_offset, bar_len,
2550 offsetof(struct pci_config, notify));
2551
2552 /*
2553 * 4.1.4.4.1:
2554 *
2555 * The device MUST present at least one notification capability.
2556 */
2557 bar_offset += bar_len;
2558 bar_len = sizeof(((struct virtio_pci_mmio *)0)->notify);
2559
2560 /*
2561 * 4.1.4.4.1:
2562 *
2563 * The cap.offset MUST be 2-byte aligned.
2564 */
2565 assert(pci->common.cap_next % 2 == 0);
2566
2567 /* FIXME: Use a non-zero notify_off, for per-queue notification? */
2568 /*
2569 * 4.1.4.4.1:
2570 *
2571 * The value cap.length presented by the device MUST be at least 2 and
2572 * MUST be large enough to support queue notification offsets for all
2573 * supported queues in all possible configurations.
2574 */
2575 assert(bar_len >= 2);
2576
2577 init_cap(&pci->notify.cap, sizeof(pci->notify),
2578 VIRTIO_PCI_CAP_NOTIFY_CFG,
2579 bar_offset, bar_len,
2580 offsetof(struct pci_config, isr));
2581
2582 bar_offset += bar_len;
2583 bar_len = sizeof(((struct virtio_pci_mmio *)0)->isr);
2584 /*
2585 * 4.1.4.5.1:
2586 *
2587 * The device MUST present at least one VIRTIO_PCI_CAP_ISR_CFG
2588 * capability.
2589 */
2590 init_cap(&pci->isr, sizeof(pci->isr),
2591 VIRTIO_PCI_CAP_ISR_CFG,
2592 bar_offset, bar_len,
2593 offsetof(struct pci_config, cfg_access));
2594
2595 /*
2596 * 4.1.4.7.1:
2597 *
2598 * The device MUST present at least one VIRTIO_PCI_CAP_PCI_CFG
2599 * capability.
2600 */
2601 /* This doesn't have any presence in the BAR */
2602 init_cap(&pci->cfg_access.cap, sizeof(pci->cfg_access),
2603 VIRTIO_PCI_CAP_PCI_CFG,
2604 0, 0, 0);
2605
2606 bar_offset += bar_len + sizeof(((struct virtio_pci_mmio *)0)->padding);
2607 assert(bar_offset == sizeof(struct virtio_pci_mmio));
2608
2609 /*
2610 * This gets sewn in and length set in set_device_config().
2611 * Some devices don't have a device configuration interface, so
2612 * we never expose this if we don't call set_device_config().
2613 */
2614 init_cap(&pci->device, sizeof(pci->device), VIRTIO_PCI_CAP_DEVICE_CFG,
2615 bar_offset, 0, 0);
2616}
2617
2618/*
2619 * This routine does all the creation and setup of a new device, but we don't
2620 * actually place the MMIO region until we know the size (if any) of the
2621 * device-specific config. And we don't actually start the service threads
2622 * until later.
2623 *
2624 * See what I mean about userspace being boring?
2625 */
2626static struct device *new_pci_device(const char *name, u16 type,
2627 u8 class, u8 subclass)
2628{
2629 struct device *dev = malloc(sizeof(*dev));
2630
2631 /* Now we populate the fields one at a time. */
2632 dev->name = name;
2633 dev->vq = NULL;
2634 dev->running = false;
2635 dev->wrote_features_ok = false;
2636 dev->mmio_size = sizeof(struct virtio_pci_mmio);
2637 dev->mmio = calloc(1, dev->mmio_size);
2638 dev->features = (u64)1 << VIRTIO_F_VERSION_1;
2639 dev->features_accepted = 0;
2640
2641 if (devices.device_num + 1 >= MAX_PCI_DEVICES)
2642 errx(1, "Can only handle 31 PCI devices");
2643
2644 init_pci_config(&dev->config, type, class, subclass);
2645 assert(!devices.pci[devices.device_num+1]);
2646 devices.pci[++devices.device_num] = dev;
2647
2648 return dev;
2649}
2650
2651/*
2652 * Our first setup routine is the console. It's a fairly simple device, but
2653 * UNIX tty handling makes it uglier than it could be.
2654 */
2655static void setup_console(void)
2656{
2657 struct device *dev;
2658 struct virtio_console_config conf;
2659
2660 /* If we can save the initial standard input settings... */
2661 if (tcgetattr(STDIN_FILENO, &orig_term) == 0) {
2662 struct termios term = orig_term;
2663 /*
2664 * Then we turn off echo, line buffering and ^C etc: We want a
2665 * raw input stream to the Guest.
2666 */
2667 term.c_lflag &= ~(ISIG|ICANON|ECHO);
2668 tcsetattr(STDIN_FILENO, TCSANOW, &term);
2669 }
2670
2671 dev = new_pci_device("console", VIRTIO_ID_CONSOLE, 0x07, 0x00);
2672
2673 /* We store the console state in dev->priv, and initialize it. */
2674 dev->priv = malloc(sizeof(struct console_abort));
2675 ((struct console_abort *)dev->priv)->count = 0;
2676
2677 /*
2678 * The console needs two virtqueues: the input then the output. When
2679 * they put something the input queue, we make sure we're listening to
2680 * stdin. When they put something in the output queue, we write it to
2681 * stdout.
2682 */
2683 add_pci_virtqueue(dev, console_input, "input");
2684 add_pci_virtqueue(dev, console_output, "output");
2685
2686 /* We need a configuration area for the emerg_wr early writes. */
2687 add_pci_feature(dev, VIRTIO_CONSOLE_F_EMERG_WRITE);
2688 set_device_config(dev, &conf, sizeof(conf));
2689
2690 verbose("device %u: console\n", devices.device_num);
2691}
2692/*:*/
2693
2694/*M:010
2695 * Inter-guest networking is an interesting area. Simplest is to have a
2696 * --sharenet=<name> option which opens or creates a named pipe. This can be
2697 * used to send packets to another guest in a 1:1 manner.
2698 *
2699 * More sophisticated is to use one of the tools developed for project like UML
2700 * to do networking.
2701 *
2702 * Faster is to do virtio bonding in kernel. Doing this 1:1 would be
2703 * completely generic ("here's my vring, attach to your vring") and would work
2704 * for any traffic. Of course, namespace and permissions issues need to be
2705 * dealt with. A more sophisticated "multi-channel" virtio_net.c could hide
2706 * multiple inter-guest channels behind one interface, although it would
2707 * require some manner of hotplugging new virtio channels.
2708 *
2709 * Finally, we could use a virtio network switch in the kernel, ie. vhost.
2710:*/
2711
2712static u32 str2ip(const char *ipaddr)
2713{
2714 unsigned int b[4];
2715
2716 if (sscanf(ipaddr, "%u.%u.%u.%u", &b[0], &b[1], &b[2], &b[3]) != 4)
2717 errx(1, "Failed to parse IP address '%s'", ipaddr);
2718 return (b[0] << 24) | (b[1] << 16) | (b[2] << 8) | b[3];
2719}
2720
2721static void str2mac(const char *macaddr, unsigned char mac[6])
2722{
2723 unsigned int m[6];
2724 if (sscanf(macaddr, "%02x:%02x:%02x:%02x:%02x:%02x",
2725 &m[0], &m[1], &m[2], &m[3], &m[4], &m[5]) != 6)
2726 errx(1, "Failed to parse mac address '%s'", macaddr);
2727 mac[0] = m[0];
2728 mac[1] = m[1];
2729 mac[2] = m[2];
2730 mac[3] = m[3];
2731 mac[4] = m[4];
2732 mac[5] = m[5];
2733}
2734
2735/*
2736 * This code is "adapted" from libbridge: it attaches the Host end of the
2737 * network device to the bridge device specified by the command line.
2738 *
2739 * This is yet another James Morris contribution (I'm an IP-level guy, so I
2740 * dislike bridging), and I just try not to break it.
2741 */
2742static void add_to_bridge(int fd, const char *if_name, const char *br_name)
2743{
2744 int ifidx;
2745 struct ifreq ifr;
2746
2747 if (!*br_name)
2748 errx(1, "must specify bridge name");
2749
2750 ifidx = if_nametoindex(if_name);
2751 if (!ifidx)
2752 errx(1, "interface %s does not exist!", if_name);
2753
2754 strncpy(ifr.ifr_name, br_name, IFNAMSIZ);
2755 ifr.ifr_name[IFNAMSIZ-1] = '\0';
2756 ifr.ifr_ifindex = ifidx;
2757 if (ioctl(fd, SIOCBRADDIF, &ifr) < 0)
2758 err(1, "can't add %s to bridge %s", if_name, br_name);
2759}
2760
2761/*
2762 * This sets up the Host end of the network device with an IP address, brings
2763 * it up so packets will flow, the copies the MAC address into the hwaddr
2764 * pointer.
2765 */
2766static void configure_device(int fd, const char *tapif, u32 ipaddr)
2767{
2768 struct ifreq ifr;
2769 struct sockaddr_in sin;
2770
2771 memset(&ifr, 0, sizeof(ifr));
2772 strcpy(ifr.ifr_name, tapif);
2773
2774 /* Don't read these incantations. Just cut & paste them like I did! */
2775 sin.sin_family = AF_INET;
2776 sin.sin_addr.s_addr = htonl(ipaddr);
2777 memcpy(&ifr.ifr_addr, &sin, sizeof(sin));
2778 if (ioctl(fd, SIOCSIFADDR, &ifr) != 0)
2779 err(1, "Setting %s interface address", tapif);
2780 ifr.ifr_flags = IFF_UP;
2781 if (ioctl(fd, SIOCSIFFLAGS, &ifr) != 0)
2782 err(1, "Bringing interface %s up", tapif);
2783}
2784
2785static int get_tun_device(char tapif[IFNAMSIZ])
2786{
2787 struct ifreq ifr;
2788 int vnet_hdr_sz;
2789 int netfd;
2790
2791 /* Start with this zeroed. Messy but sure. */
2792 memset(&ifr, 0, sizeof(ifr));
2793
2794 /*
2795 * We open the /dev/net/tun device and tell it we want a tap device. A
2796 * tap device is like a tun device, only somehow different. To tell
2797 * the truth, I completely blundered my way through this code, but it
2798 * works now!
2799 */
2800 netfd = open_or_die("/dev/net/tun", O_RDWR);
2801 ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_VNET_HDR;
2802 strcpy(ifr.ifr_name, "tap%d");
2803 if (ioctl(netfd, TUNSETIFF, &ifr) != 0)
2804 err(1, "configuring /dev/net/tun");
2805
2806 if (ioctl(netfd, TUNSETOFFLOAD,
2807 TUN_F_CSUM|TUN_F_TSO4|TUN_F_TSO6|TUN_F_TSO_ECN) != 0)
2808 err(1, "Could not set features for tun device");
2809
2810 /*
2811 * We don't need checksums calculated for packets coming in this
2812 * device: trust us!
2813 */
2814 ioctl(netfd, TUNSETNOCSUM, 1);
2815
2816 /*
2817 * In virtio before 1.0 (aka legacy virtio), we added a 16-bit
2818 * field at the end of the network header iff
2819 * VIRTIO_NET_F_MRG_RXBUF was negotiated. For virtio 1.0,
2820 * that became the norm, but we need to tell the tun device
2821 * about our expanded header (which is called
2822 * virtio_net_hdr_mrg_rxbuf in the legacy system).
2823 */
2824 vnet_hdr_sz = sizeof(struct virtio_net_hdr_v1);
2825 if (ioctl(netfd, TUNSETVNETHDRSZ, &vnet_hdr_sz) != 0)
2826 err(1, "Setting tun header size to %u", vnet_hdr_sz);
2827
2828 memcpy(tapif, ifr.ifr_name, IFNAMSIZ);
2829 return netfd;
2830}
2831
2832/*L:195
2833 * Our network is a Host<->Guest network. This can either use bridging or
2834 * routing, but the principle is the same: it uses the "tun" device to inject
2835 * packets into the Host as if they came in from a normal network card. We
2836 * just shunt packets between the Guest and the tun device.
2837 */
2838static void setup_tun_net(char *arg)
2839{
2840 struct device *dev;
2841 struct net_info *net_info = malloc(sizeof(*net_info));
2842 int ipfd;
2843 u32 ip = INADDR_ANY;
2844 bool bridging = false;
2845 char tapif[IFNAMSIZ], *p;
2846 struct virtio_net_config conf;
2847
2848 net_info->tunfd = get_tun_device(tapif);
2849
2850 /* First we create a new network device. */
2851 dev = new_pci_device("net", VIRTIO_ID_NET, 0x02, 0x00);
2852 dev->priv = net_info;
2853
2854 /* Network devices need a recv and a send queue, just like console. */
2855 add_pci_virtqueue(dev, net_input, "rx");
2856 add_pci_virtqueue(dev, net_output, "tx");
2857
2858 /*
2859 * We need a socket to perform the magic network ioctls to bring up the
2860 * tap interface, connect to the bridge etc. Any socket will do!
2861 */
2862 ipfd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
2863 if (ipfd < 0)
2864 err(1, "opening IP socket");
2865
2866 /* If the command line was --tunnet=bridge:<name> do bridging. */
2867 if (!strncmp(BRIDGE_PFX, arg, strlen(BRIDGE_PFX))) {
2868 arg += strlen(BRIDGE_PFX);
2869 bridging = true;
2870 }
2871
2872 /* A mac address may follow the bridge name or IP address */
2873 p = strchr(arg, ':');
2874 if (p) {
2875 str2mac(p+1, conf.mac);
2876 add_pci_feature(dev, VIRTIO_NET_F_MAC);
2877 *p = '\0';
2878 }
2879
2880 /* arg is now either an IP address or a bridge name */
2881 if (bridging)
2882 add_to_bridge(ipfd, tapif, arg);
2883 else
2884 ip = str2ip(arg);
2885
2886 /* Set up the tun device. */
2887 configure_device(ipfd, tapif, ip);
2888
2889 /* Expect Guest to handle everything except UFO */
2890 add_pci_feature(dev, VIRTIO_NET_F_CSUM);
2891 add_pci_feature(dev, VIRTIO_NET_F_GUEST_CSUM);
2892 add_pci_feature(dev, VIRTIO_NET_F_GUEST_TSO4);
2893 add_pci_feature(dev, VIRTIO_NET_F_GUEST_TSO6);
2894 add_pci_feature(dev, VIRTIO_NET_F_GUEST_ECN);
2895 add_pci_feature(dev, VIRTIO_NET_F_HOST_TSO4);
2896 add_pci_feature(dev, VIRTIO_NET_F_HOST_TSO6);
2897 add_pci_feature(dev, VIRTIO_NET_F_HOST_ECN);
2898 /* We handle indirect ring entries */
2899 add_pci_feature(dev, VIRTIO_RING_F_INDIRECT_DESC);
2900 set_device_config(dev, &conf, sizeof(conf));
2901
2902 /* We don't need the socket any more; setup is done. */
2903 close(ipfd);
2904
2905 if (bridging)
2906 verbose("device %u: tun %s attached to bridge: %s\n",
2907 devices.device_num, tapif, arg);
2908 else
2909 verbose("device %u: tun %s: %s\n",
2910 devices.device_num, tapif, arg);
2911}
2912/*:*/
2913
2914/* This hangs off device->priv. */
2915struct vblk_info {
2916 /* The size of the file. */
2917 off64_t len;
2918
2919 /* The file descriptor for the file. */
2920 int fd;
2921
2922};
2923
2924/*L:210
2925 * The Disk
2926 *
2927 * The disk only has one virtqueue, so it only has one thread. It is really
2928 * simple: the Guest asks for a block number and we read or write that position
2929 * in the file.
2930 *
2931 * Before we serviced each virtqueue in a separate thread, that was unacceptably
2932 * slow: the Guest waits until the read is finished before running anything
2933 * else, even if it could have been doing useful work.
2934 *
2935 * We could have used async I/O, except it's reputed to suck so hard that
2936 * characters actually go missing from your code when you try to use it.
2937 */
2938static void blk_request(struct virtqueue *vq)
2939{
2940 struct vblk_info *vblk = vq->dev->priv;
2941 unsigned int head, out_num, in_num, wlen;
2942 int ret, i;
2943 u8 *in;
2944 struct virtio_blk_outhdr out;
2945 struct iovec iov[vq->vring.num];
2946 off64_t off;
2947
2948 /*
2949 * Get the next request, where we normally wait. It triggers the
2950 * interrupt to acknowledge previously serviced requests (if any).
2951 */
2952 head = wait_for_vq_desc(vq, iov, &out_num, &in_num);
2953
2954 /* Copy the output header from the front of the iov (adjusts iov) */
2955 iov_consume(vq->dev, iov, out_num, &out, sizeof(out));
2956
2957 /* Find and trim end of iov input array, for our status byte. */
2958 in = NULL;
2959 for (i = out_num + in_num - 1; i >= out_num; i--) {
2960 if (iov[i].iov_len > 0) {
2961 in = iov[i].iov_base + iov[i].iov_len - 1;
2962 iov[i].iov_len--;
2963 break;
2964 }
2965 }
2966 if (!in)
2967 bad_driver_vq(vq, "Bad virtblk cmd with no room for status");
2968
2969 /*
2970 * For historical reasons, block operations are expressed in 512 byte
2971 * "sectors".
2972 */
2973 off = out.sector * 512;
2974
2975 if (out.type & VIRTIO_BLK_T_OUT) {
2976 /*
2977 * Write
2978 *
2979 * Move to the right location in the block file. This can fail
2980 * if they try to write past end.
2981 */
2982 if (lseek64(vblk->fd, off, SEEK_SET) != off)
2983 err(1, "Bad seek to sector %llu", out.sector);
2984
2985 ret = writev(vblk->fd, iov, out_num);
2986 verbose("WRITE to sector %llu: %i\n", out.sector, ret);
2987
2988 /*
2989 * Grr... Now we know how long the descriptor they sent was, we
2990 * make sure they didn't try to write over the end of the block
2991 * file (possibly extending it).
2992 */
2993 if (ret > 0 && off + ret > vblk->len) {
2994 /* Trim it back to the correct length */
2995 ftruncate64(vblk->fd, vblk->len);
2996 /* Die, bad Guest, die. */
2997 bad_driver_vq(vq, "Write past end %llu+%u", off, ret);
2998 }
2999
3000 wlen = sizeof(*in);
3001 *in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR);
3002 } else if (out.type & VIRTIO_BLK_T_FLUSH) {
3003 /* Flush */
3004 ret = fdatasync(vblk->fd);
3005 verbose("FLUSH fdatasync: %i\n", ret);
3006 wlen = sizeof(*in);
3007 *in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR);
3008 } else {
3009 /*
3010 * Read
3011 *
3012 * Move to the right location in the block file. This can fail
3013 * if they try to read past end.
3014 */
3015 if (lseek64(vblk->fd, off, SEEK_SET) != off)
3016 err(1, "Bad seek to sector %llu", out.sector);
3017
3018 ret = readv(vblk->fd, iov + out_num, in_num);
3019 if (ret >= 0) {
3020 wlen = sizeof(*in) + ret;
3021 *in = VIRTIO_BLK_S_OK;
3022 } else {
3023 wlen = sizeof(*in);
3024 *in = VIRTIO_BLK_S_IOERR;
3025 }
3026 }
3027
3028 /* Finished that request. */
3029 add_used(vq, head, wlen);
3030}
3031
3032/*L:198 This actually sets up a virtual block device. */
3033static void setup_block_file(const char *filename)
3034{
3035 struct device *dev;
3036 struct vblk_info *vblk;
3037 struct virtio_blk_config conf;
3038
3039 /* Create the device. */
3040 dev = new_pci_device("block", VIRTIO_ID_BLOCK, 0x01, 0x80);
3041
3042 /* The device has one virtqueue, where the Guest places requests. */
3043 add_pci_virtqueue(dev, blk_request, "request");
3044
3045 /* Allocate the room for our own bookkeeping */
3046 vblk = dev->priv = malloc(sizeof(*vblk));
3047
3048 /* First we open the file and store the length. */
3049 vblk->fd = open_or_die(filename, O_RDWR|O_LARGEFILE);
3050 vblk->len = lseek64(vblk->fd, 0, SEEK_END);
3051
3052 /* Tell Guest how many sectors this device has. */
3053 conf.capacity = cpu_to_le64(vblk->len / 512);
3054
3055 /*
3056 * Tell Guest not to put in too many descriptors at once: two are used
3057 * for the in and out elements.
3058 */
3059 add_pci_feature(dev, VIRTIO_BLK_F_SEG_MAX);
3060 conf.seg_max = cpu_to_le32(VIRTQUEUE_NUM - 2);
3061
3062 set_device_config(dev, &conf, sizeof(struct virtio_blk_config));
3063
3064 verbose("device %u: virtblock %llu sectors\n",
3065 devices.device_num, le64_to_cpu(conf.capacity));
3066}
3067
3068/*L:211
3069 * Our random number generator device reads from /dev/urandom into the Guest's
3070 * input buffers. The usual case is that the Guest doesn't want random numbers
3071 * and so has no buffers although /dev/urandom is still readable, whereas
3072 * console is the reverse.
3073 *
3074 * The same logic applies, however.
3075 */
3076struct rng_info {
3077 int rfd;
3078};
3079
3080static void rng_input(struct virtqueue *vq)
3081{
3082 int len;
3083 unsigned int head, in_num, out_num, totlen = 0;
3084 struct rng_info *rng_info = vq->dev->priv;
3085 struct iovec iov[vq->vring.num];
3086
3087 /* First we need a buffer from the Guests's virtqueue. */
3088 head = wait_for_vq_desc(vq, iov, &out_num, &in_num);
3089 if (out_num)
3090 bad_driver_vq(vq, "Output buffers in rng?");
3091
3092 /*
3093 * Just like the console write, we loop to cover the whole iovec.
3094 * In this case, short reads actually happen quite a bit.
3095 */
3096 while (!iov_empty(iov, in_num)) {
3097 len = readv(rng_info->rfd, iov, in_num);
3098 if (len <= 0)
3099 err(1, "Read from /dev/urandom gave %i", len);
3100 iov_consume(vq->dev, iov, in_num, NULL, len);
3101 totlen += len;
3102 }
3103
3104 /* Tell the Guest about the new input. */
3105 add_used(vq, head, totlen);
3106}
3107
3108/*L:199
3109 * This creates a "hardware" random number device for the Guest.
3110 */
3111static void setup_rng(void)
3112{
3113 struct device *dev;
3114 struct rng_info *rng_info = malloc(sizeof(*rng_info));
3115
3116 /* Our device's private info simply contains the /dev/urandom fd. */
3117 rng_info->rfd = open_or_die("/dev/urandom", O_RDONLY);
3118
3119 /* Create the new device. */
3120 dev = new_pci_device("rng", VIRTIO_ID_RNG, 0xff, 0);
3121 dev->priv = rng_info;
3122
3123 /* The device has one virtqueue, where the Guest places inbufs. */
3124 add_pci_virtqueue(dev, rng_input, "input");
3125
3126 /* We don't have any configuration space */
3127 no_device_config(dev);
3128
3129 verbose("device %u: rng\n", devices.device_num);
3130}
3131/* That's the end of device setup. */
3132
3133/*L:230 Reboot is pretty easy: clean up and exec() the Launcher afresh. */
3134static void __attribute__((noreturn)) restart_guest(void)
3135{
3136 unsigned int i;
3137
3138 /*
3139 * Since we don't track all open fds, we simply close everything beyond
3140 * stderr.
3141 */
3142 for (i = 3; i < FD_SETSIZE; i++)
3143 close(i);
3144
3145 /* Reset all the devices (kills all threads). */
3146 cleanup_devices();
3147
3148 execv(main_args[0], main_args);
3149 err(1, "Could not exec %s", main_args[0]);
3150}
3151
3152/*L:220
3153 * Finally we reach the core of the Launcher which runs the Guest, serves
3154 * its input and output, and finally, lays it to rest.
3155 */
3156static void __attribute__((noreturn)) run_guest(void)
3157{
3158 for (;;) {
3159 struct lguest_pending notify;
3160 int readval;
3161
3162 /* We read from the /dev/lguest device to run the Guest. */
3163 readval = pread(lguest_fd, ¬ify, sizeof(notify), cpu_id);
3164 if (readval == sizeof(notify)) {
3165 if (notify.trap == 13) {
3166 verbose("Emulating instruction at %#x\n",
3167 getreg(eip));
3168 emulate_insn(notify.insn);
3169 } else if (notify.trap == 14) {
3170 verbose("Emulating MMIO at %#x\n",
3171 getreg(eip));
3172 emulate_mmio(notify.addr, notify.insn);
3173 } else
3174 errx(1, "Unknown trap %i addr %#08x\n",
3175 notify.trap, notify.addr);
3176 /* ENOENT means the Guest died. Reading tells us why. */
3177 } else if (errno == ENOENT) {
3178 char reason[1024] = { 0 };
3179 pread(lguest_fd, reason, sizeof(reason)-1, cpu_id);
3180 errx(1, "%s", reason);
3181 /* ERESTART means that we need to reboot the guest */
3182 } else if (errno == ERESTART) {
3183 restart_guest();
3184 /* Anything else means a bug or incompatible change. */
3185 } else
3186 err(1, "Running guest failed");
3187 }
3188}
3189/*L:240
3190 * This is the end of the Launcher. The good news: we are over halfway
3191 * through! The bad news: the most fiendish part of the code still lies ahead
3192 * of us.
3193 *
3194 * Are you ready? Take a deep breath and join me in the core of the Host, in
3195 * "make Host".
3196:*/
3197
3198static struct option opts[] = {
3199 { "verbose", 0, NULL, 'v' },
3200 { "tunnet", 1, NULL, 't' },
3201 { "block", 1, NULL, 'b' },
3202 { "rng", 0, NULL, 'r' },
3203 { "initrd", 1, NULL, 'i' },
3204 { "username", 1, NULL, 'u' },
3205 { "chroot", 1, NULL, 'c' },
3206 { NULL },
3207};
3208static void usage(void)
3209{
3210 errx(1, "Usage: lguest [--verbose] "
3211 "[--tunnet=(<ipaddr>:<macaddr>|bridge:<bridgename>:<macaddr>)\n"
3212 "|--block=<filename>|--initrd=<filename>]...\n"
3213 "<mem-in-mb> vmlinux [args...]");
3214}
3215
3216/*L:105 The main routine is where the real work begins: */
3217int main(int argc, char *argv[])
3218{
3219 /* Memory, code startpoint and size of the (optional) initrd. */
3220 unsigned long mem = 0, start, initrd_size = 0;
3221 /* Two temporaries. */
3222 int i, c;
3223 /* The boot information for the Guest. */
3224 struct boot_params *boot;
3225 /* If they specify an initrd file to load. */
3226 const char *initrd_name = NULL;
3227
3228 /* Password structure for initgroups/setres[gu]id */
3229 struct passwd *user_details = NULL;
3230
3231 /* Directory to chroot to */
3232 char *chroot_path = NULL;
3233
3234 /* Save the args: we "reboot" by execing ourselves again. */
3235 main_args = argv;
3236
3237 /*
3238 * First we initialize the device list. We remember next interrupt
3239 * number to use for devices (1: remember that 0 is used by the timer).
3240 */
3241 devices.next_irq = 1;
3242
3243 /* We're CPU 0. In fact, that's the only CPU possible right now. */
3244 cpu_id = 0;
3245
3246 /*
3247 * We need to know how much memory so we can set up the device
3248 * descriptor and memory pages for the devices as we parse the command
3249 * line. So we quickly look through the arguments to find the amount
3250 * of memory now.
3251 */
3252 for (i = 1; i < argc; i++) {
3253 if (argv[i][0] != '-') {
3254 mem = atoi(argv[i]) * 1024 * 1024;
3255 /*
3256 * We start by mapping anonymous pages over all of
3257 * guest-physical memory range. This fills it with 0,
3258 * and ensures that the Guest won't be killed when it
3259 * tries to access it.
3260 */
3261 guest_base = map_zeroed_pages(mem / getpagesize()
3262 + DEVICE_PAGES);
3263 guest_limit = mem;
3264 guest_max = guest_mmio = mem + DEVICE_PAGES*getpagesize();
3265 break;
3266 }
3267 }
3268
3269 /* We always have a console device, and it's always device 1. */
3270 setup_console();
3271
3272 /* The options are fairly straight-forward */
3273 while ((c = getopt_long(argc, argv, "v", opts, NULL)) != EOF) {
3274 switch (c) {
3275 case 'v':
3276 verbose = true;
3277 break;
3278 case 't':
3279 setup_tun_net(optarg);
3280 break;
3281 case 'b':
3282 setup_block_file(optarg);
3283 break;
3284 case 'r':
3285 setup_rng();
3286 break;
3287 case 'i':
3288 initrd_name = optarg;
3289 break;
3290 case 'u':
3291 user_details = getpwnam(optarg);
3292 if (!user_details)
3293 err(1, "getpwnam failed, incorrect username?");
3294 break;
3295 case 'c':
3296 chroot_path = optarg;
3297 break;
3298 default:
3299 warnx("Unknown argument %s", argv[optind]);
3300 usage();
3301 }
3302 }
3303 /*
3304 * After the other arguments we expect memory and kernel image name,
3305 * followed by command line arguments for the kernel.
3306 */
3307 if (optind + 2 > argc)
3308 usage();
3309
3310 verbose("Guest base is at %p\n", guest_base);
3311
3312 /* Initialize the (fake) PCI host bridge device. */
3313 init_pci_host_bridge();
3314
3315 /* Now we load the kernel */
3316 start = load_kernel(open_or_die(argv[optind+1], O_RDONLY));
3317
3318 /* Boot information is stashed at physical address 0 */
3319 boot = from_guest_phys(0);
3320
3321 /* Map the initrd image if requested (at top of physical memory) */
3322 if (initrd_name) {
3323 initrd_size = load_initrd(initrd_name, mem);
3324 /*
3325 * These are the location in the Linux boot header where the
3326 * start and size of the initrd are expected to be found.
3327 */
3328 boot->hdr.ramdisk_image = mem - initrd_size;
3329 boot->hdr.ramdisk_size = initrd_size;
3330 /* The bootloader type 0xFF means "unknown"; that's OK. */
3331 boot->hdr.type_of_loader = 0xFF;
3332 }
3333
3334 /*
3335 * The Linux boot header contains an "E820" memory map: ours is a
3336 * simple, single region.
3337 */
3338 boot->e820_entries = 1;
3339 boot->e820_map[0] = ((struct e820entry) { 0, mem, E820_RAM });
3340 /*
3341 * The boot header contains a command line pointer: we put the command
3342 * line after the boot header.
3343 */
3344 boot->hdr.cmd_line_ptr = to_guest_phys(boot + 1);
3345 /* We use a simple helper to copy the arguments separated by spaces. */
3346 concat((char *)(boot + 1), argv+optind+2);
3347
3348 /* Set kernel alignment to 16M (CONFIG_PHYSICAL_ALIGN) */
3349 boot->hdr.kernel_alignment = 0x1000000;
3350
3351 /* Boot protocol version: 2.07 supports the fields for lguest. */
3352 boot->hdr.version = 0x207;
3353
3354 /* The hardware_subarch value of "1" tells the Guest it's an lguest. */
3355 boot->hdr.hardware_subarch = 1;
3356
3357 /* Tell the entry path not to try to reload segment registers. */
3358 boot->hdr.loadflags |= KEEP_SEGMENTS;
3359
3360 /* We tell the kernel to initialize the Guest. */
3361 tell_kernel(start);
3362
3363 /* Ensure that we terminate if a device-servicing child dies. */
3364 signal(SIGCHLD, kill_launcher);
3365
3366 /* If we exit via err(), this kills all the threads, restores tty. */
3367 atexit(cleanup_devices);
3368
3369 /* If requested, chroot to a directory */
3370 if (chroot_path) {
3371 if (chroot(chroot_path) != 0)
3372 err(1, "chroot(\"%s\") failed", chroot_path);
3373
3374 if (chdir("/") != 0)
3375 err(1, "chdir(\"/\") failed");
3376
3377 verbose("chroot done\n");
3378 }
3379
3380 /* If requested, drop privileges */
3381 if (user_details) {
3382 uid_t u;
3383 gid_t g;
3384
3385 u = user_details->pw_uid;
3386 g = user_details->pw_gid;
3387
3388 if (initgroups(user_details->pw_name, g) != 0)
3389 err(1, "initgroups failed");
3390
3391 if (setresgid(g, g, g) != 0)
3392 err(1, "setresgid failed");
3393
3394 if (setresuid(u, u, u) != 0)
3395 err(1, "setresuid failed");
3396
3397 verbose("Dropping privileges completed\n");
3398 }
3399
3400 /* Finally, run the Guest. This doesn't return. */
3401 run_guest();
3402}
3403/*:*/
3404
3405/*M:999
3406 * Mastery is done: you now know everything I do.
3407 *
3408 * But surely you have seen code, features and bugs in your wanderings which
3409 * you now yearn to attack? That is the real game, and I look forward to you
3410 * patching and forking lguest into the Your-Name-Here-visor.
3411 *
3412 * Farewell, and good coding!
3413 * Rusty Russell.
3414 */