Loading...
Note: File does not exist in v5.4.
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * AMD Memory Encryption Support
4 *
5 * Copyright (C) 2019 SUSE
6 *
7 * Author: Joerg Roedel <jroedel@suse.de>
8 */
9
10#define pr_fmt(fmt) "SEV: " fmt
11
12#include <linux/sched/debug.h> /* For show_regs() */
13#include <linux/percpu-defs.h>
14#include <linux/mem_encrypt.h>
15#include <linux/printk.h>
16#include <linux/mm_types.h>
17#include <linux/set_memory.h>
18#include <linux/memblock.h>
19#include <linux/kernel.h>
20#include <linux/mm.h>
21
22#include <asm/cpu_entry_area.h>
23#include <asm/stacktrace.h>
24#include <asm/sev.h>
25#include <asm/insn-eval.h>
26#include <asm/fpu/internal.h>
27#include <asm/processor.h>
28#include <asm/realmode.h>
29#include <asm/traps.h>
30#include <asm/svm.h>
31#include <asm/smp.h>
32#include <asm/cpu.h>
33
34#define DR7_RESET_VALUE 0x400
35
36/* For early boot hypervisor communication in SEV-ES enabled guests */
37static struct ghcb boot_ghcb_page __bss_decrypted __aligned(PAGE_SIZE);
38
39/*
40 * Needs to be in the .data section because we need it NULL before bss is
41 * cleared
42 */
43static struct ghcb __initdata *boot_ghcb;
44
45/* #VC handler runtime per-CPU data */
46struct sev_es_runtime_data {
47 struct ghcb ghcb_page;
48
49 /* Physical storage for the per-CPU IST stack of the #VC handler */
50 char ist_stack[EXCEPTION_STKSZ] __aligned(PAGE_SIZE);
51
52 /*
53 * Physical storage for the per-CPU fall-back stack of the #VC handler.
54 * The fall-back stack is used when it is not safe to switch back to the
55 * interrupted stack in the #VC entry code.
56 */
57 char fallback_stack[EXCEPTION_STKSZ] __aligned(PAGE_SIZE);
58
59 /*
60 * Reserve one page per CPU as backup storage for the unencrypted GHCB.
61 * It is needed when an NMI happens while the #VC handler uses the real
62 * GHCB, and the NMI handler itself is causing another #VC exception. In
63 * that case the GHCB content of the first handler needs to be backed up
64 * and restored.
65 */
66 struct ghcb backup_ghcb;
67
68 /*
69 * Mark the per-cpu GHCBs as in-use to detect nested #VC exceptions.
70 * There is no need for it to be atomic, because nothing is written to
71 * the GHCB between the read and the write of ghcb_active. So it is safe
72 * to use it when a nested #VC exception happens before the write.
73 *
74 * This is necessary for example in the #VC->NMI->#VC case when the NMI
75 * happens while the first #VC handler uses the GHCB. When the NMI code
76 * raises a second #VC handler it might overwrite the contents of the
77 * GHCB written by the first handler. To avoid this the content of the
78 * GHCB is saved and restored when the GHCB is detected to be in use
79 * already.
80 */
81 bool ghcb_active;
82 bool backup_ghcb_active;
83
84 /*
85 * Cached DR7 value - write it on DR7 writes and return it on reads.
86 * That value will never make it to the real hardware DR7 as debugging
87 * is currently unsupported in SEV-ES guests.
88 */
89 unsigned long dr7;
90};
91
92struct ghcb_state {
93 struct ghcb *ghcb;
94};
95
96static DEFINE_PER_CPU(struct sev_es_runtime_data*, runtime_data);
97DEFINE_STATIC_KEY_FALSE(sev_es_enable_key);
98
99/* Needed in vc_early_forward_exception */
100void do_early_exception(struct pt_regs *regs, int trapnr);
101
102static void __init setup_vc_stacks(int cpu)
103{
104 struct sev_es_runtime_data *data;
105 struct cpu_entry_area *cea;
106 unsigned long vaddr;
107 phys_addr_t pa;
108
109 data = per_cpu(runtime_data, cpu);
110 cea = get_cpu_entry_area(cpu);
111
112 /* Map #VC IST stack */
113 vaddr = CEA_ESTACK_BOT(&cea->estacks, VC);
114 pa = __pa(data->ist_stack);
115 cea_set_pte((void *)vaddr, pa, PAGE_KERNEL);
116
117 /* Map VC fall-back stack */
118 vaddr = CEA_ESTACK_BOT(&cea->estacks, VC2);
119 pa = __pa(data->fallback_stack);
120 cea_set_pte((void *)vaddr, pa, PAGE_KERNEL);
121}
122
123static __always_inline bool on_vc_stack(struct pt_regs *regs)
124{
125 unsigned long sp = regs->sp;
126
127 /* User-mode RSP is not trusted */
128 if (user_mode(regs))
129 return false;
130
131 /* SYSCALL gap still has user-mode RSP */
132 if (ip_within_syscall_gap(regs))
133 return false;
134
135 return ((sp >= __this_cpu_ist_bottom_va(VC)) && (sp < __this_cpu_ist_top_va(VC)));
136}
137
138/*
139 * This function handles the case when an NMI is raised in the #VC
140 * exception handler entry code, before the #VC handler has switched off
141 * its IST stack. In this case, the IST entry for #VC must be adjusted,
142 * so that any nested #VC exception will not overwrite the stack
143 * contents of the interrupted #VC handler.
144 *
145 * The IST entry is adjusted unconditionally so that it can be also be
146 * unconditionally adjusted back in __sev_es_ist_exit(). Otherwise a
147 * nested sev_es_ist_exit() call may adjust back the IST entry too
148 * early.
149 *
150 * The __sev_es_ist_enter() and __sev_es_ist_exit() functions always run
151 * on the NMI IST stack, as they are only called from NMI handling code
152 * right now.
153 */
154void noinstr __sev_es_ist_enter(struct pt_regs *regs)
155{
156 unsigned long old_ist, new_ist;
157
158 /* Read old IST entry */
159 new_ist = old_ist = __this_cpu_read(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC]);
160
161 /*
162 * If NMI happened while on the #VC IST stack, set the new IST
163 * value below regs->sp, so that the interrupted stack frame is
164 * not overwritten by subsequent #VC exceptions.
165 */
166 if (on_vc_stack(regs))
167 new_ist = regs->sp;
168
169 /*
170 * Reserve additional 8 bytes and store old IST value so this
171 * adjustment can be unrolled in __sev_es_ist_exit().
172 */
173 new_ist -= sizeof(old_ist);
174 *(unsigned long *)new_ist = old_ist;
175
176 /* Set new IST entry */
177 this_cpu_write(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC], new_ist);
178}
179
180void noinstr __sev_es_ist_exit(void)
181{
182 unsigned long ist;
183
184 /* Read IST entry */
185 ist = __this_cpu_read(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC]);
186
187 if (WARN_ON(ist == __this_cpu_ist_top_va(VC)))
188 return;
189
190 /* Read back old IST entry and write it to the TSS */
191 this_cpu_write(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC], *(unsigned long *)ist);
192}
193
194/*
195 * Nothing shall interrupt this code path while holding the per-CPU
196 * GHCB. The backup GHCB is only for NMIs interrupting this path.
197 *
198 * Callers must disable local interrupts around it.
199 */
200static noinstr struct ghcb *__sev_get_ghcb(struct ghcb_state *state)
201{
202 struct sev_es_runtime_data *data;
203 struct ghcb *ghcb;
204
205 WARN_ON(!irqs_disabled());
206
207 data = this_cpu_read(runtime_data);
208 ghcb = &data->ghcb_page;
209
210 if (unlikely(data->ghcb_active)) {
211 /* GHCB is already in use - save its contents */
212
213 if (unlikely(data->backup_ghcb_active)) {
214 /*
215 * Backup-GHCB is also already in use. There is no way
216 * to continue here so just kill the machine. To make
217 * panic() work, mark GHCBs inactive so that messages
218 * can be printed out.
219 */
220 data->ghcb_active = false;
221 data->backup_ghcb_active = false;
222
223 instrumentation_begin();
224 panic("Unable to handle #VC exception! GHCB and Backup GHCB are already in use");
225 instrumentation_end();
226 }
227
228 /* Mark backup_ghcb active before writing to it */
229 data->backup_ghcb_active = true;
230
231 state->ghcb = &data->backup_ghcb;
232
233 /* Backup GHCB content */
234 *state->ghcb = *ghcb;
235 } else {
236 state->ghcb = NULL;
237 data->ghcb_active = true;
238 }
239
240 return ghcb;
241}
242
243/* Needed in vc_early_forward_exception */
244void do_early_exception(struct pt_regs *regs, int trapnr);
245
246static inline u64 sev_es_rd_ghcb_msr(void)
247{
248 return __rdmsr(MSR_AMD64_SEV_ES_GHCB);
249}
250
251static __always_inline void sev_es_wr_ghcb_msr(u64 val)
252{
253 u32 low, high;
254
255 low = (u32)(val);
256 high = (u32)(val >> 32);
257
258 native_wrmsr(MSR_AMD64_SEV_ES_GHCB, low, high);
259}
260
261static int vc_fetch_insn_kernel(struct es_em_ctxt *ctxt,
262 unsigned char *buffer)
263{
264 return copy_from_kernel_nofault(buffer, (unsigned char *)ctxt->regs->ip, MAX_INSN_SIZE);
265}
266
267static enum es_result __vc_decode_user_insn(struct es_em_ctxt *ctxt)
268{
269 char buffer[MAX_INSN_SIZE];
270 int insn_bytes;
271
272 insn_bytes = insn_fetch_from_user_inatomic(ctxt->regs, buffer);
273 if (insn_bytes == 0) {
274 /* Nothing could be copied */
275 ctxt->fi.vector = X86_TRAP_PF;
276 ctxt->fi.error_code = X86_PF_INSTR | X86_PF_USER;
277 ctxt->fi.cr2 = ctxt->regs->ip;
278 return ES_EXCEPTION;
279 } else if (insn_bytes == -EINVAL) {
280 /* Effective RIP could not be calculated */
281 ctxt->fi.vector = X86_TRAP_GP;
282 ctxt->fi.error_code = 0;
283 ctxt->fi.cr2 = 0;
284 return ES_EXCEPTION;
285 }
286
287 if (!insn_decode_from_regs(&ctxt->insn, ctxt->regs, buffer, insn_bytes))
288 return ES_DECODE_FAILED;
289
290 if (ctxt->insn.immediate.got)
291 return ES_OK;
292 else
293 return ES_DECODE_FAILED;
294}
295
296static enum es_result __vc_decode_kern_insn(struct es_em_ctxt *ctxt)
297{
298 char buffer[MAX_INSN_SIZE];
299 int res, ret;
300
301 res = vc_fetch_insn_kernel(ctxt, buffer);
302 if (res) {
303 ctxt->fi.vector = X86_TRAP_PF;
304 ctxt->fi.error_code = X86_PF_INSTR;
305 ctxt->fi.cr2 = ctxt->regs->ip;
306 return ES_EXCEPTION;
307 }
308
309 ret = insn_decode(&ctxt->insn, buffer, MAX_INSN_SIZE, INSN_MODE_64);
310 if (ret < 0)
311 return ES_DECODE_FAILED;
312 else
313 return ES_OK;
314}
315
316static enum es_result vc_decode_insn(struct es_em_ctxt *ctxt)
317{
318 if (user_mode(ctxt->regs))
319 return __vc_decode_user_insn(ctxt);
320 else
321 return __vc_decode_kern_insn(ctxt);
322}
323
324static enum es_result vc_write_mem(struct es_em_ctxt *ctxt,
325 char *dst, char *buf, size_t size)
326{
327 unsigned long error_code = X86_PF_PROT | X86_PF_WRITE;
328 char __user *target = (char __user *)dst;
329 u64 d8;
330 u32 d4;
331 u16 d2;
332 u8 d1;
333
334 /*
335 * This function uses __put_user() independent of whether kernel or user
336 * memory is accessed. This works fine because __put_user() does no
337 * sanity checks of the pointer being accessed. All that it does is
338 * to report when the access failed.
339 *
340 * Also, this function runs in atomic context, so __put_user() is not
341 * allowed to sleep. The page-fault handler detects that it is running
342 * in atomic context and will not try to take mmap_sem and handle the
343 * fault, so additional pagefault_enable()/disable() calls are not
344 * needed.
345 *
346 * The access can't be done via copy_to_user() here because
347 * vc_write_mem() must not use string instructions to access unsafe
348 * memory. The reason is that MOVS is emulated by the #VC handler by
349 * splitting the move up into a read and a write and taking a nested #VC
350 * exception on whatever of them is the MMIO access. Using string
351 * instructions here would cause infinite nesting.
352 */
353 switch (size) {
354 case 1:
355 memcpy(&d1, buf, 1);
356 if (__put_user(d1, target))
357 goto fault;
358 break;
359 case 2:
360 memcpy(&d2, buf, 2);
361 if (__put_user(d2, target))
362 goto fault;
363 break;
364 case 4:
365 memcpy(&d4, buf, 4);
366 if (__put_user(d4, target))
367 goto fault;
368 break;
369 case 8:
370 memcpy(&d8, buf, 8);
371 if (__put_user(d8, target))
372 goto fault;
373 break;
374 default:
375 WARN_ONCE(1, "%s: Invalid size: %zu\n", __func__, size);
376 return ES_UNSUPPORTED;
377 }
378
379 return ES_OK;
380
381fault:
382 if (user_mode(ctxt->regs))
383 error_code |= X86_PF_USER;
384
385 ctxt->fi.vector = X86_TRAP_PF;
386 ctxt->fi.error_code = error_code;
387 ctxt->fi.cr2 = (unsigned long)dst;
388
389 return ES_EXCEPTION;
390}
391
392static enum es_result vc_read_mem(struct es_em_ctxt *ctxt,
393 char *src, char *buf, size_t size)
394{
395 unsigned long error_code = X86_PF_PROT;
396 char __user *s = (char __user *)src;
397 u64 d8;
398 u32 d4;
399 u16 d2;
400 u8 d1;
401
402 /*
403 * This function uses __get_user() independent of whether kernel or user
404 * memory is accessed. This works fine because __get_user() does no
405 * sanity checks of the pointer being accessed. All that it does is
406 * to report when the access failed.
407 *
408 * Also, this function runs in atomic context, so __get_user() is not
409 * allowed to sleep. The page-fault handler detects that it is running
410 * in atomic context and will not try to take mmap_sem and handle the
411 * fault, so additional pagefault_enable()/disable() calls are not
412 * needed.
413 *
414 * The access can't be done via copy_from_user() here because
415 * vc_read_mem() must not use string instructions to access unsafe
416 * memory. The reason is that MOVS is emulated by the #VC handler by
417 * splitting the move up into a read and a write and taking a nested #VC
418 * exception on whatever of them is the MMIO access. Using string
419 * instructions here would cause infinite nesting.
420 */
421 switch (size) {
422 case 1:
423 if (__get_user(d1, s))
424 goto fault;
425 memcpy(buf, &d1, 1);
426 break;
427 case 2:
428 if (__get_user(d2, s))
429 goto fault;
430 memcpy(buf, &d2, 2);
431 break;
432 case 4:
433 if (__get_user(d4, s))
434 goto fault;
435 memcpy(buf, &d4, 4);
436 break;
437 case 8:
438 if (__get_user(d8, s))
439 goto fault;
440 memcpy(buf, &d8, 8);
441 break;
442 default:
443 WARN_ONCE(1, "%s: Invalid size: %zu\n", __func__, size);
444 return ES_UNSUPPORTED;
445 }
446
447 return ES_OK;
448
449fault:
450 if (user_mode(ctxt->regs))
451 error_code |= X86_PF_USER;
452
453 ctxt->fi.vector = X86_TRAP_PF;
454 ctxt->fi.error_code = error_code;
455 ctxt->fi.cr2 = (unsigned long)src;
456
457 return ES_EXCEPTION;
458}
459
460static enum es_result vc_slow_virt_to_phys(struct ghcb *ghcb, struct es_em_ctxt *ctxt,
461 unsigned long vaddr, phys_addr_t *paddr)
462{
463 unsigned long va = (unsigned long)vaddr;
464 unsigned int level;
465 phys_addr_t pa;
466 pgd_t *pgd;
467 pte_t *pte;
468
469 pgd = __va(read_cr3_pa());
470 pgd = &pgd[pgd_index(va)];
471 pte = lookup_address_in_pgd(pgd, va, &level);
472 if (!pte) {
473 ctxt->fi.vector = X86_TRAP_PF;
474 ctxt->fi.cr2 = vaddr;
475 ctxt->fi.error_code = 0;
476
477 if (user_mode(ctxt->regs))
478 ctxt->fi.error_code |= X86_PF_USER;
479
480 return ES_EXCEPTION;
481 }
482
483 if (WARN_ON_ONCE(pte_val(*pte) & _PAGE_ENC))
484 /* Emulated MMIO to/from encrypted memory not supported */
485 return ES_UNSUPPORTED;
486
487 pa = (phys_addr_t)pte_pfn(*pte) << PAGE_SHIFT;
488 pa |= va & ~page_level_mask(level);
489
490 *paddr = pa;
491
492 return ES_OK;
493}
494
495/* Include code shared with pre-decompression boot stage */
496#include "sev-shared.c"
497
498static noinstr void __sev_put_ghcb(struct ghcb_state *state)
499{
500 struct sev_es_runtime_data *data;
501 struct ghcb *ghcb;
502
503 WARN_ON(!irqs_disabled());
504
505 data = this_cpu_read(runtime_data);
506 ghcb = &data->ghcb_page;
507
508 if (state->ghcb) {
509 /* Restore GHCB from Backup */
510 *ghcb = *state->ghcb;
511 data->backup_ghcb_active = false;
512 state->ghcb = NULL;
513 } else {
514 /*
515 * Invalidate the GHCB so a VMGEXIT instruction issued
516 * from userspace won't appear to be valid.
517 */
518 vc_ghcb_invalidate(ghcb);
519 data->ghcb_active = false;
520 }
521}
522
523void noinstr __sev_es_nmi_complete(void)
524{
525 struct ghcb_state state;
526 struct ghcb *ghcb;
527
528 ghcb = __sev_get_ghcb(&state);
529
530 vc_ghcb_invalidate(ghcb);
531 ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_NMI_COMPLETE);
532 ghcb_set_sw_exit_info_1(ghcb, 0);
533 ghcb_set_sw_exit_info_2(ghcb, 0);
534
535 sev_es_wr_ghcb_msr(__pa_nodebug(ghcb));
536 VMGEXIT();
537
538 __sev_put_ghcb(&state);
539}
540
541static u64 get_jump_table_addr(void)
542{
543 struct ghcb_state state;
544 unsigned long flags;
545 struct ghcb *ghcb;
546 u64 ret = 0;
547
548 local_irq_save(flags);
549
550 ghcb = __sev_get_ghcb(&state);
551
552 vc_ghcb_invalidate(ghcb);
553 ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_AP_JUMP_TABLE);
554 ghcb_set_sw_exit_info_1(ghcb, SVM_VMGEXIT_GET_AP_JUMP_TABLE);
555 ghcb_set_sw_exit_info_2(ghcb, 0);
556
557 sev_es_wr_ghcb_msr(__pa(ghcb));
558 VMGEXIT();
559
560 if (ghcb_sw_exit_info_1_is_valid(ghcb) &&
561 ghcb_sw_exit_info_2_is_valid(ghcb))
562 ret = ghcb->save.sw_exit_info_2;
563
564 __sev_put_ghcb(&state);
565
566 local_irq_restore(flags);
567
568 return ret;
569}
570
571int sev_es_setup_ap_jump_table(struct real_mode_header *rmh)
572{
573 u16 startup_cs, startup_ip;
574 phys_addr_t jump_table_pa;
575 u64 jump_table_addr;
576 u16 __iomem *jump_table;
577
578 jump_table_addr = get_jump_table_addr();
579
580 /* On UP guests there is no jump table so this is not a failure */
581 if (!jump_table_addr)
582 return 0;
583
584 /* Check if AP Jump Table is page-aligned */
585 if (jump_table_addr & ~PAGE_MASK)
586 return -EINVAL;
587
588 jump_table_pa = jump_table_addr & PAGE_MASK;
589
590 startup_cs = (u16)(rmh->trampoline_start >> 4);
591 startup_ip = (u16)(rmh->sev_es_trampoline_start -
592 rmh->trampoline_start);
593
594 jump_table = ioremap_encrypted(jump_table_pa, PAGE_SIZE);
595 if (!jump_table)
596 return -EIO;
597
598 writew(startup_ip, &jump_table[0]);
599 writew(startup_cs, &jump_table[1]);
600
601 iounmap(jump_table);
602
603 return 0;
604}
605
606/*
607 * This is needed by the OVMF UEFI firmware which will use whatever it finds in
608 * the GHCB MSR as its GHCB to talk to the hypervisor. So make sure the per-cpu
609 * runtime GHCBs used by the kernel are also mapped in the EFI page-table.
610 */
611int __init sev_es_efi_map_ghcbs(pgd_t *pgd)
612{
613 struct sev_es_runtime_data *data;
614 unsigned long address, pflags;
615 int cpu;
616 u64 pfn;
617
618 if (!sev_es_active())
619 return 0;
620
621 pflags = _PAGE_NX | _PAGE_RW;
622
623 for_each_possible_cpu(cpu) {
624 data = per_cpu(runtime_data, cpu);
625
626 address = __pa(&data->ghcb_page);
627 pfn = address >> PAGE_SHIFT;
628
629 if (kernel_map_pages_in_pgd(pgd, pfn, address, 1, pflags))
630 return 1;
631 }
632
633 return 0;
634}
635
636static enum es_result vc_handle_msr(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
637{
638 struct pt_regs *regs = ctxt->regs;
639 enum es_result ret;
640 u64 exit_info_1;
641
642 /* Is it a WRMSR? */
643 exit_info_1 = (ctxt->insn.opcode.bytes[1] == 0x30) ? 1 : 0;
644
645 ghcb_set_rcx(ghcb, regs->cx);
646 if (exit_info_1) {
647 ghcb_set_rax(ghcb, regs->ax);
648 ghcb_set_rdx(ghcb, regs->dx);
649 }
650
651 ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_MSR, exit_info_1, 0);
652
653 if ((ret == ES_OK) && (!exit_info_1)) {
654 regs->ax = ghcb->save.rax;
655 regs->dx = ghcb->save.rdx;
656 }
657
658 return ret;
659}
660
661/*
662 * This function runs on the first #VC exception after the kernel
663 * switched to virtual addresses.
664 */
665static bool __init sev_es_setup_ghcb(void)
666{
667 /* First make sure the hypervisor talks a supported protocol. */
668 if (!sev_es_negotiate_protocol())
669 return false;
670
671 /*
672 * Clear the boot_ghcb. The first exception comes in before the bss
673 * section is cleared.
674 */
675 memset(&boot_ghcb_page, 0, PAGE_SIZE);
676
677 /* Alright - Make the boot-ghcb public */
678 boot_ghcb = &boot_ghcb_page;
679
680 return true;
681}
682
683#ifdef CONFIG_HOTPLUG_CPU
684static void sev_es_ap_hlt_loop(void)
685{
686 struct ghcb_state state;
687 struct ghcb *ghcb;
688
689 ghcb = __sev_get_ghcb(&state);
690
691 while (true) {
692 vc_ghcb_invalidate(ghcb);
693 ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_AP_HLT_LOOP);
694 ghcb_set_sw_exit_info_1(ghcb, 0);
695 ghcb_set_sw_exit_info_2(ghcb, 0);
696
697 sev_es_wr_ghcb_msr(__pa(ghcb));
698 VMGEXIT();
699
700 /* Wakeup signal? */
701 if (ghcb_sw_exit_info_2_is_valid(ghcb) &&
702 ghcb->save.sw_exit_info_2)
703 break;
704 }
705
706 __sev_put_ghcb(&state);
707}
708
709/*
710 * Play_dead handler when running under SEV-ES. This is needed because
711 * the hypervisor can't deliver an SIPI request to restart the AP.
712 * Instead the kernel has to issue a VMGEXIT to halt the VCPU until the
713 * hypervisor wakes it up again.
714 */
715static void sev_es_play_dead(void)
716{
717 play_dead_common();
718
719 /* IRQs now disabled */
720
721 sev_es_ap_hlt_loop();
722
723 /*
724 * If we get here, the VCPU was woken up again. Jump to CPU
725 * startup code to get it back online.
726 */
727 start_cpu0();
728}
729#else /* CONFIG_HOTPLUG_CPU */
730#define sev_es_play_dead native_play_dead
731#endif /* CONFIG_HOTPLUG_CPU */
732
733#ifdef CONFIG_SMP
734static void __init sev_es_setup_play_dead(void)
735{
736 smp_ops.play_dead = sev_es_play_dead;
737}
738#else
739static inline void sev_es_setup_play_dead(void) { }
740#endif
741
742static void __init alloc_runtime_data(int cpu)
743{
744 struct sev_es_runtime_data *data;
745
746 data = memblock_alloc(sizeof(*data), PAGE_SIZE);
747 if (!data)
748 panic("Can't allocate SEV-ES runtime data");
749
750 per_cpu(runtime_data, cpu) = data;
751}
752
753static void __init init_ghcb(int cpu)
754{
755 struct sev_es_runtime_data *data;
756 int err;
757
758 data = per_cpu(runtime_data, cpu);
759
760 err = early_set_memory_decrypted((unsigned long)&data->ghcb_page,
761 sizeof(data->ghcb_page));
762 if (err)
763 panic("Can't map GHCBs unencrypted");
764
765 memset(&data->ghcb_page, 0, sizeof(data->ghcb_page));
766
767 data->ghcb_active = false;
768 data->backup_ghcb_active = false;
769}
770
771void __init sev_es_init_vc_handling(void)
772{
773 int cpu;
774
775 BUILD_BUG_ON(offsetof(struct sev_es_runtime_data, ghcb_page) % PAGE_SIZE);
776
777 if (!sev_es_active())
778 return;
779
780 if (!sev_es_check_cpu_features())
781 panic("SEV-ES CPU Features missing");
782
783 /* Enable SEV-ES special handling */
784 static_branch_enable(&sev_es_enable_key);
785
786 /* Initialize per-cpu GHCB pages */
787 for_each_possible_cpu(cpu) {
788 alloc_runtime_data(cpu);
789 init_ghcb(cpu);
790 setup_vc_stacks(cpu);
791 }
792
793 sev_es_setup_play_dead();
794
795 /* Secondary CPUs use the runtime #VC handler */
796 initial_vc_handler = (unsigned long)kernel_exc_vmm_communication;
797}
798
799static void __init vc_early_forward_exception(struct es_em_ctxt *ctxt)
800{
801 int trapnr = ctxt->fi.vector;
802
803 if (trapnr == X86_TRAP_PF)
804 native_write_cr2(ctxt->fi.cr2);
805
806 ctxt->regs->orig_ax = ctxt->fi.error_code;
807 do_early_exception(ctxt->regs, trapnr);
808}
809
810static long *vc_insn_get_reg(struct es_em_ctxt *ctxt)
811{
812 long *reg_array;
813 int offset;
814
815 reg_array = (long *)ctxt->regs;
816 offset = insn_get_modrm_reg_off(&ctxt->insn, ctxt->regs);
817
818 if (offset < 0)
819 return NULL;
820
821 offset /= sizeof(long);
822
823 return reg_array + offset;
824}
825
826static long *vc_insn_get_rm(struct es_em_ctxt *ctxt)
827{
828 long *reg_array;
829 int offset;
830
831 reg_array = (long *)ctxt->regs;
832 offset = insn_get_modrm_rm_off(&ctxt->insn, ctxt->regs);
833
834 if (offset < 0)
835 return NULL;
836
837 offset /= sizeof(long);
838
839 return reg_array + offset;
840}
841static enum es_result vc_do_mmio(struct ghcb *ghcb, struct es_em_ctxt *ctxt,
842 unsigned int bytes, bool read)
843{
844 u64 exit_code, exit_info_1, exit_info_2;
845 unsigned long ghcb_pa = __pa(ghcb);
846 enum es_result res;
847 phys_addr_t paddr;
848 void __user *ref;
849
850 ref = insn_get_addr_ref(&ctxt->insn, ctxt->regs);
851 if (ref == (void __user *)-1L)
852 return ES_UNSUPPORTED;
853
854 exit_code = read ? SVM_VMGEXIT_MMIO_READ : SVM_VMGEXIT_MMIO_WRITE;
855
856 res = vc_slow_virt_to_phys(ghcb, ctxt, (unsigned long)ref, &paddr);
857 if (res != ES_OK) {
858 if (res == ES_EXCEPTION && !read)
859 ctxt->fi.error_code |= X86_PF_WRITE;
860
861 return res;
862 }
863
864 exit_info_1 = paddr;
865 /* Can never be greater than 8 */
866 exit_info_2 = bytes;
867
868 ghcb_set_sw_scratch(ghcb, ghcb_pa + offsetof(struct ghcb, shared_buffer));
869
870 return sev_es_ghcb_hv_call(ghcb, ctxt, exit_code, exit_info_1, exit_info_2);
871}
872
873static enum es_result vc_handle_mmio_twobyte_ops(struct ghcb *ghcb,
874 struct es_em_ctxt *ctxt)
875{
876 struct insn *insn = &ctxt->insn;
877 unsigned int bytes = 0;
878 enum es_result ret;
879 int sign_byte;
880 long *reg_data;
881
882 switch (insn->opcode.bytes[1]) {
883 /* MMIO Read w/ zero-extension */
884 case 0xb6:
885 bytes = 1;
886 fallthrough;
887 case 0xb7:
888 if (!bytes)
889 bytes = 2;
890
891 ret = vc_do_mmio(ghcb, ctxt, bytes, true);
892 if (ret)
893 break;
894
895 /* Zero extend based on operand size */
896 reg_data = vc_insn_get_reg(ctxt);
897 if (!reg_data)
898 return ES_DECODE_FAILED;
899
900 memset(reg_data, 0, insn->opnd_bytes);
901
902 memcpy(reg_data, ghcb->shared_buffer, bytes);
903 break;
904
905 /* MMIO Read w/ sign-extension */
906 case 0xbe:
907 bytes = 1;
908 fallthrough;
909 case 0xbf:
910 if (!bytes)
911 bytes = 2;
912
913 ret = vc_do_mmio(ghcb, ctxt, bytes, true);
914 if (ret)
915 break;
916
917 /* Sign extend based on operand size */
918 reg_data = vc_insn_get_reg(ctxt);
919 if (!reg_data)
920 return ES_DECODE_FAILED;
921
922 if (bytes == 1) {
923 u8 *val = (u8 *)ghcb->shared_buffer;
924
925 sign_byte = (*val & 0x80) ? 0xff : 0x00;
926 } else {
927 u16 *val = (u16 *)ghcb->shared_buffer;
928
929 sign_byte = (*val & 0x8000) ? 0xff : 0x00;
930 }
931 memset(reg_data, sign_byte, insn->opnd_bytes);
932
933 memcpy(reg_data, ghcb->shared_buffer, bytes);
934 break;
935
936 default:
937 ret = ES_UNSUPPORTED;
938 }
939
940 return ret;
941}
942
943/*
944 * The MOVS instruction has two memory operands, which raises the
945 * problem that it is not known whether the access to the source or the
946 * destination caused the #VC exception (and hence whether an MMIO read
947 * or write operation needs to be emulated).
948 *
949 * Instead of playing games with walking page-tables and trying to guess
950 * whether the source or destination is an MMIO range, split the move
951 * into two operations, a read and a write with only one memory operand.
952 * This will cause a nested #VC exception on the MMIO address which can
953 * then be handled.
954 *
955 * This implementation has the benefit that it also supports MOVS where
956 * source _and_ destination are MMIO regions.
957 *
958 * It will slow MOVS on MMIO down a lot, but in SEV-ES guests it is a
959 * rare operation. If it turns out to be a performance problem the split
960 * operations can be moved to memcpy_fromio() and memcpy_toio().
961 */
962static enum es_result vc_handle_mmio_movs(struct es_em_ctxt *ctxt,
963 unsigned int bytes)
964{
965 unsigned long ds_base, es_base;
966 unsigned char *src, *dst;
967 unsigned char buffer[8];
968 enum es_result ret;
969 bool rep;
970 int off;
971
972 ds_base = insn_get_seg_base(ctxt->regs, INAT_SEG_REG_DS);
973 es_base = insn_get_seg_base(ctxt->regs, INAT_SEG_REG_ES);
974
975 if (ds_base == -1L || es_base == -1L) {
976 ctxt->fi.vector = X86_TRAP_GP;
977 ctxt->fi.error_code = 0;
978 return ES_EXCEPTION;
979 }
980
981 src = ds_base + (unsigned char *)ctxt->regs->si;
982 dst = es_base + (unsigned char *)ctxt->regs->di;
983
984 ret = vc_read_mem(ctxt, src, buffer, bytes);
985 if (ret != ES_OK)
986 return ret;
987
988 ret = vc_write_mem(ctxt, dst, buffer, bytes);
989 if (ret != ES_OK)
990 return ret;
991
992 if (ctxt->regs->flags & X86_EFLAGS_DF)
993 off = -bytes;
994 else
995 off = bytes;
996
997 ctxt->regs->si += off;
998 ctxt->regs->di += off;
999
1000 rep = insn_has_rep_prefix(&ctxt->insn);
1001 if (rep)
1002 ctxt->regs->cx -= 1;
1003
1004 if (!rep || ctxt->regs->cx == 0)
1005 return ES_OK;
1006 else
1007 return ES_RETRY;
1008}
1009
1010static enum es_result vc_handle_mmio(struct ghcb *ghcb,
1011 struct es_em_ctxt *ctxt)
1012{
1013 struct insn *insn = &ctxt->insn;
1014 unsigned int bytes = 0;
1015 enum es_result ret;
1016 long *reg_data;
1017
1018 switch (insn->opcode.bytes[0]) {
1019 /* MMIO Write */
1020 case 0x88:
1021 bytes = 1;
1022 fallthrough;
1023 case 0x89:
1024 if (!bytes)
1025 bytes = insn->opnd_bytes;
1026
1027 reg_data = vc_insn_get_reg(ctxt);
1028 if (!reg_data)
1029 return ES_DECODE_FAILED;
1030
1031 memcpy(ghcb->shared_buffer, reg_data, bytes);
1032
1033 ret = vc_do_mmio(ghcb, ctxt, bytes, false);
1034 break;
1035
1036 case 0xc6:
1037 bytes = 1;
1038 fallthrough;
1039 case 0xc7:
1040 if (!bytes)
1041 bytes = insn->opnd_bytes;
1042
1043 memcpy(ghcb->shared_buffer, insn->immediate1.bytes, bytes);
1044
1045 ret = vc_do_mmio(ghcb, ctxt, bytes, false);
1046 break;
1047
1048 /* MMIO Read */
1049 case 0x8a:
1050 bytes = 1;
1051 fallthrough;
1052 case 0x8b:
1053 if (!bytes)
1054 bytes = insn->opnd_bytes;
1055
1056 ret = vc_do_mmio(ghcb, ctxt, bytes, true);
1057 if (ret)
1058 break;
1059
1060 reg_data = vc_insn_get_reg(ctxt);
1061 if (!reg_data)
1062 return ES_DECODE_FAILED;
1063
1064 /* Zero-extend for 32-bit operation */
1065 if (bytes == 4)
1066 *reg_data = 0;
1067
1068 memcpy(reg_data, ghcb->shared_buffer, bytes);
1069 break;
1070
1071 /* MOVS instruction */
1072 case 0xa4:
1073 bytes = 1;
1074 fallthrough;
1075 case 0xa5:
1076 if (!bytes)
1077 bytes = insn->opnd_bytes;
1078
1079 ret = vc_handle_mmio_movs(ctxt, bytes);
1080 break;
1081 /* Two-Byte Opcodes */
1082 case 0x0f:
1083 ret = vc_handle_mmio_twobyte_ops(ghcb, ctxt);
1084 break;
1085 default:
1086 ret = ES_UNSUPPORTED;
1087 }
1088
1089 return ret;
1090}
1091
1092static enum es_result vc_handle_dr7_write(struct ghcb *ghcb,
1093 struct es_em_ctxt *ctxt)
1094{
1095 struct sev_es_runtime_data *data = this_cpu_read(runtime_data);
1096 long val, *reg = vc_insn_get_rm(ctxt);
1097 enum es_result ret;
1098
1099 if (!reg)
1100 return ES_DECODE_FAILED;
1101
1102 val = *reg;
1103
1104 /* Upper 32 bits must be written as zeroes */
1105 if (val >> 32) {
1106 ctxt->fi.vector = X86_TRAP_GP;
1107 ctxt->fi.error_code = 0;
1108 return ES_EXCEPTION;
1109 }
1110
1111 /* Clear out other reserved bits and set bit 10 */
1112 val = (val & 0xffff23ffL) | BIT(10);
1113
1114 /* Early non-zero writes to DR7 are not supported */
1115 if (!data && (val & ~DR7_RESET_VALUE))
1116 return ES_UNSUPPORTED;
1117
1118 /* Using a value of 0 for ExitInfo1 means RAX holds the value */
1119 ghcb_set_rax(ghcb, val);
1120 ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_WRITE_DR7, 0, 0);
1121 if (ret != ES_OK)
1122 return ret;
1123
1124 if (data)
1125 data->dr7 = val;
1126
1127 return ES_OK;
1128}
1129
1130static enum es_result vc_handle_dr7_read(struct ghcb *ghcb,
1131 struct es_em_ctxt *ctxt)
1132{
1133 struct sev_es_runtime_data *data = this_cpu_read(runtime_data);
1134 long *reg = vc_insn_get_rm(ctxt);
1135
1136 if (!reg)
1137 return ES_DECODE_FAILED;
1138
1139 if (data)
1140 *reg = data->dr7;
1141 else
1142 *reg = DR7_RESET_VALUE;
1143
1144 return ES_OK;
1145}
1146
1147static enum es_result vc_handle_wbinvd(struct ghcb *ghcb,
1148 struct es_em_ctxt *ctxt)
1149{
1150 return sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_WBINVD, 0, 0);
1151}
1152
1153static enum es_result vc_handle_rdpmc(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
1154{
1155 enum es_result ret;
1156
1157 ghcb_set_rcx(ghcb, ctxt->regs->cx);
1158
1159 ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_RDPMC, 0, 0);
1160 if (ret != ES_OK)
1161 return ret;
1162
1163 if (!(ghcb_rax_is_valid(ghcb) && ghcb_rdx_is_valid(ghcb)))
1164 return ES_VMM_ERROR;
1165
1166 ctxt->regs->ax = ghcb->save.rax;
1167 ctxt->regs->dx = ghcb->save.rdx;
1168
1169 return ES_OK;
1170}
1171
1172static enum es_result vc_handle_monitor(struct ghcb *ghcb,
1173 struct es_em_ctxt *ctxt)
1174{
1175 /*
1176 * Treat it as a NOP and do not leak a physical address to the
1177 * hypervisor.
1178 */
1179 return ES_OK;
1180}
1181
1182static enum es_result vc_handle_mwait(struct ghcb *ghcb,
1183 struct es_em_ctxt *ctxt)
1184{
1185 /* Treat the same as MONITOR/MONITORX */
1186 return ES_OK;
1187}
1188
1189static enum es_result vc_handle_vmmcall(struct ghcb *ghcb,
1190 struct es_em_ctxt *ctxt)
1191{
1192 enum es_result ret;
1193
1194 ghcb_set_rax(ghcb, ctxt->regs->ax);
1195 ghcb_set_cpl(ghcb, user_mode(ctxt->regs) ? 3 : 0);
1196
1197 if (x86_platform.hyper.sev_es_hcall_prepare)
1198 x86_platform.hyper.sev_es_hcall_prepare(ghcb, ctxt->regs);
1199
1200 ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_VMMCALL, 0, 0);
1201 if (ret != ES_OK)
1202 return ret;
1203
1204 if (!ghcb_rax_is_valid(ghcb))
1205 return ES_VMM_ERROR;
1206
1207 ctxt->regs->ax = ghcb->save.rax;
1208
1209 /*
1210 * Call sev_es_hcall_finish() after regs->ax is already set.
1211 * This allows the hypervisor handler to overwrite it again if
1212 * necessary.
1213 */
1214 if (x86_platform.hyper.sev_es_hcall_finish &&
1215 !x86_platform.hyper.sev_es_hcall_finish(ghcb, ctxt->regs))
1216 return ES_VMM_ERROR;
1217
1218 return ES_OK;
1219}
1220
1221static enum es_result vc_handle_trap_ac(struct ghcb *ghcb,
1222 struct es_em_ctxt *ctxt)
1223{
1224 /*
1225 * Calling ecx_alignment_check() directly does not work, because it
1226 * enables IRQs and the GHCB is active. Forward the exception and call
1227 * it later from vc_forward_exception().
1228 */
1229 ctxt->fi.vector = X86_TRAP_AC;
1230 ctxt->fi.error_code = 0;
1231 return ES_EXCEPTION;
1232}
1233
1234static enum es_result vc_handle_exitcode(struct es_em_ctxt *ctxt,
1235 struct ghcb *ghcb,
1236 unsigned long exit_code)
1237{
1238 enum es_result result;
1239
1240 switch (exit_code) {
1241 case SVM_EXIT_READ_DR7:
1242 result = vc_handle_dr7_read(ghcb, ctxt);
1243 break;
1244 case SVM_EXIT_WRITE_DR7:
1245 result = vc_handle_dr7_write(ghcb, ctxt);
1246 break;
1247 case SVM_EXIT_EXCP_BASE + X86_TRAP_AC:
1248 result = vc_handle_trap_ac(ghcb, ctxt);
1249 break;
1250 case SVM_EXIT_RDTSC:
1251 case SVM_EXIT_RDTSCP:
1252 result = vc_handle_rdtsc(ghcb, ctxt, exit_code);
1253 break;
1254 case SVM_EXIT_RDPMC:
1255 result = vc_handle_rdpmc(ghcb, ctxt);
1256 break;
1257 case SVM_EXIT_INVD:
1258 pr_err_ratelimited("#VC exception for INVD??? Seriously???\n");
1259 result = ES_UNSUPPORTED;
1260 break;
1261 case SVM_EXIT_CPUID:
1262 result = vc_handle_cpuid(ghcb, ctxt);
1263 break;
1264 case SVM_EXIT_IOIO:
1265 result = vc_handle_ioio(ghcb, ctxt);
1266 break;
1267 case SVM_EXIT_MSR:
1268 result = vc_handle_msr(ghcb, ctxt);
1269 break;
1270 case SVM_EXIT_VMMCALL:
1271 result = vc_handle_vmmcall(ghcb, ctxt);
1272 break;
1273 case SVM_EXIT_WBINVD:
1274 result = vc_handle_wbinvd(ghcb, ctxt);
1275 break;
1276 case SVM_EXIT_MONITOR:
1277 result = vc_handle_monitor(ghcb, ctxt);
1278 break;
1279 case SVM_EXIT_MWAIT:
1280 result = vc_handle_mwait(ghcb, ctxt);
1281 break;
1282 case SVM_EXIT_NPF:
1283 result = vc_handle_mmio(ghcb, ctxt);
1284 break;
1285 default:
1286 /*
1287 * Unexpected #VC exception
1288 */
1289 result = ES_UNSUPPORTED;
1290 }
1291
1292 return result;
1293}
1294
1295static __always_inline void vc_forward_exception(struct es_em_ctxt *ctxt)
1296{
1297 long error_code = ctxt->fi.error_code;
1298 int trapnr = ctxt->fi.vector;
1299
1300 ctxt->regs->orig_ax = ctxt->fi.error_code;
1301
1302 switch (trapnr) {
1303 case X86_TRAP_GP:
1304 exc_general_protection(ctxt->regs, error_code);
1305 break;
1306 case X86_TRAP_UD:
1307 exc_invalid_op(ctxt->regs);
1308 break;
1309 case X86_TRAP_PF:
1310 write_cr2(ctxt->fi.cr2);
1311 exc_page_fault(ctxt->regs, error_code);
1312 break;
1313 case X86_TRAP_AC:
1314 exc_alignment_check(ctxt->regs, error_code);
1315 break;
1316 default:
1317 pr_emerg("Unsupported exception in #VC instruction emulation - can't continue\n");
1318 BUG();
1319 }
1320}
1321
1322static __always_inline bool on_vc_fallback_stack(struct pt_regs *regs)
1323{
1324 unsigned long sp = (unsigned long)regs;
1325
1326 return (sp >= __this_cpu_ist_bottom_va(VC2) && sp < __this_cpu_ist_top_va(VC2));
1327}
1328
1329static bool vc_raw_handle_exception(struct pt_regs *regs, unsigned long error_code)
1330{
1331 struct ghcb_state state;
1332 struct es_em_ctxt ctxt;
1333 enum es_result result;
1334 struct ghcb *ghcb;
1335 bool ret = true;
1336
1337 ghcb = __sev_get_ghcb(&state);
1338
1339 vc_ghcb_invalidate(ghcb);
1340 result = vc_init_em_ctxt(&ctxt, regs, error_code);
1341
1342 if (result == ES_OK)
1343 result = vc_handle_exitcode(&ctxt, ghcb, error_code);
1344
1345 __sev_put_ghcb(&state);
1346
1347 /* Done - now check the result */
1348 switch (result) {
1349 case ES_OK:
1350 vc_finish_insn(&ctxt);
1351 break;
1352 case ES_UNSUPPORTED:
1353 pr_err_ratelimited("Unsupported exit-code 0x%02lx in #VC exception (IP: 0x%lx)\n",
1354 error_code, regs->ip);
1355 ret = false;
1356 break;
1357 case ES_VMM_ERROR:
1358 pr_err_ratelimited("Failure in communication with VMM (exit-code 0x%02lx IP: 0x%lx)\n",
1359 error_code, regs->ip);
1360 ret = false;
1361 break;
1362 case ES_DECODE_FAILED:
1363 pr_err_ratelimited("Failed to decode instruction (exit-code 0x%02lx IP: 0x%lx)\n",
1364 error_code, regs->ip);
1365 ret = false;
1366 break;
1367 case ES_EXCEPTION:
1368 vc_forward_exception(&ctxt);
1369 break;
1370 case ES_RETRY:
1371 /* Nothing to do */
1372 break;
1373 default:
1374 pr_emerg("Unknown result in %s():%d\n", __func__, result);
1375 /*
1376 * Emulating the instruction which caused the #VC exception
1377 * failed - can't continue so print debug information
1378 */
1379 BUG();
1380 }
1381
1382 return ret;
1383}
1384
1385static __always_inline bool vc_is_db(unsigned long error_code)
1386{
1387 return error_code == SVM_EXIT_EXCP_BASE + X86_TRAP_DB;
1388}
1389
1390/*
1391 * Runtime #VC exception handler when raised from kernel mode. Runs in NMI mode
1392 * and will panic when an error happens.
1393 */
1394DEFINE_IDTENTRY_VC_KERNEL(exc_vmm_communication)
1395{
1396 irqentry_state_t irq_state;
1397
1398 /*
1399 * With the current implementation it is always possible to switch to a
1400 * safe stack because #VC exceptions only happen at known places, like
1401 * intercepted instructions or accesses to MMIO areas/IO ports. They can
1402 * also happen with code instrumentation when the hypervisor intercepts
1403 * #DB, but the critical paths are forbidden to be instrumented, so #DB
1404 * exceptions currently also only happen in safe places.
1405 *
1406 * But keep this here in case the noinstr annotations are violated due
1407 * to bug elsewhere.
1408 */
1409 if (unlikely(on_vc_fallback_stack(regs))) {
1410 instrumentation_begin();
1411 panic("Can't handle #VC exception from unsupported context\n");
1412 instrumentation_end();
1413 }
1414
1415 /*
1416 * Handle #DB before calling into !noinstr code to avoid recursive #DB.
1417 */
1418 if (vc_is_db(error_code)) {
1419 exc_debug(regs);
1420 return;
1421 }
1422
1423 irq_state = irqentry_nmi_enter(regs);
1424
1425 instrumentation_begin();
1426
1427 if (!vc_raw_handle_exception(regs, error_code)) {
1428 /* Show some debug info */
1429 show_regs(regs);
1430
1431 /* Ask hypervisor to sev_es_terminate */
1432 sev_es_terminate(GHCB_SEV_ES_REASON_GENERAL_REQUEST);
1433
1434 /* If that fails and we get here - just panic */
1435 panic("Returned from Terminate-Request to Hypervisor\n");
1436 }
1437
1438 instrumentation_end();
1439 irqentry_nmi_exit(regs, irq_state);
1440}
1441
1442/*
1443 * Runtime #VC exception handler when raised from user mode. Runs in IRQ mode
1444 * and will kill the current task with SIGBUS when an error happens.
1445 */
1446DEFINE_IDTENTRY_VC_USER(exc_vmm_communication)
1447{
1448 /*
1449 * Handle #DB before calling into !noinstr code to avoid recursive #DB.
1450 */
1451 if (vc_is_db(error_code)) {
1452 noist_exc_debug(regs);
1453 return;
1454 }
1455
1456 irqentry_enter_from_user_mode(regs);
1457 instrumentation_begin();
1458
1459 if (!vc_raw_handle_exception(regs, error_code)) {
1460 /*
1461 * Do not kill the machine if user-space triggered the
1462 * exception. Send SIGBUS instead and let user-space deal with
1463 * it.
1464 */
1465 force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)0);
1466 }
1467
1468 instrumentation_end();
1469 irqentry_exit_to_user_mode(regs);
1470}
1471
1472bool __init handle_vc_boot_ghcb(struct pt_regs *regs)
1473{
1474 unsigned long exit_code = regs->orig_ax;
1475 struct es_em_ctxt ctxt;
1476 enum es_result result;
1477
1478 /* Do initial setup or terminate the guest */
1479 if (unlikely(boot_ghcb == NULL && !sev_es_setup_ghcb()))
1480 sev_es_terminate(GHCB_SEV_ES_REASON_GENERAL_REQUEST);
1481
1482 vc_ghcb_invalidate(boot_ghcb);
1483
1484 result = vc_init_em_ctxt(&ctxt, regs, exit_code);
1485 if (result == ES_OK)
1486 result = vc_handle_exitcode(&ctxt, boot_ghcb, exit_code);
1487
1488 /* Done - now check the result */
1489 switch (result) {
1490 case ES_OK:
1491 vc_finish_insn(&ctxt);
1492 break;
1493 case ES_UNSUPPORTED:
1494 early_printk("PANIC: Unsupported exit-code 0x%02lx in early #VC exception (IP: 0x%lx)\n",
1495 exit_code, regs->ip);
1496 goto fail;
1497 case ES_VMM_ERROR:
1498 early_printk("PANIC: Failure in communication with VMM (exit-code 0x%02lx IP: 0x%lx)\n",
1499 exit_code, regs->ip);
1500 goto fail;
1501 case ES_DECODE_FAILED:
1502 early_printk("PANIC: Failed to decode instruction (exit-code 0x%02lx IP: 0x%lx)\n",
1503 exit_code, regs->ip);
1504 goto fail;
1505 case ES_EXCEPTION:
1506 vc_early_forward_exception(&ctxt);
1507 break;
1508 case ES_RETRY:
1509 /* Nothing to do */
1510 break;
1511 default:
1512 BUG();
1513 }
1514
1515 return true;
1516
1517fail:
1518 show_regs(regs);
1519
1520 while (true)
1521 halt();
1522}