1// SPDX-License-Identifier: GPL-2.0-or-later
   2/* Virtio ring implementation.
   3 *
   4 *  Copyright 2007 Rusty Russell IBM Corporation
 
 
 
 
 
 
 
 
 
 
 
 
 
 
   5 */
   6#include <linux/virtio.h>
   7#include <linux/virtio_ring.h>
   8#include <linux/virtio_config.h>
   9#include <linux/device.h>
  10#include <linux/slab.h>
  11#include <linux/module.h>
  12#include <linux/hrtimer.h>
  13#include <linux/dma-mapping.h>
  14#include <xen/xen.h>
  15
  16#ifdef DEBUG
  17/* For development, we want to crash whenever the ring is screwed. */
  18#define BAD_RING(_vq, fmt, args...)				\
  19	do {							\
  20		dev_err(&(_vq)->vq.vdev->dev,			\
  21			"%s:"fmt, (_vq)->vq.name, ##args);	\
  22		BUG();						\
  23	} while (0)
  24/* Caller is supposed to guarantee no reentry. */
  25#define START_USE(_vq)						\
  26	do {							\
  27		if ((_vq)->in_use)				\
  28			panic("%s:in_use = %i\n",		\
  29			      (_vq)->vq.name, (_vq)->in_use);	\
  30		(_vq)->in_use = __LINE__;			\
  31	} while (0)
  32#define END_USE(_vq) \
  33	do { BUG_ON(!(_vq)->in_use); (_vq)->in_use = 0; } while(0)
  34#define LAST_ADD_TIME_UPDATE(_vq)				\
  35	do {							\
  36		ktime_t now = ktime_get();			\
  37								\
  38		/* No kick or get, with .1 second between?  Warn. */ \
  39		if ((_vq)->last_add_time_valid)			\
  40			WARN_ON(ktime_to_ms(ktime_sub(now,	\
  41				(_vq)->last_add_time)) > 100);	\
  42		(_vq)->last_add_time = now;			\
  43		(_vq)->last_add_time_valid = true;		\
  44	} while (0)
  45#define LAST_ADD_TIME_CHECK(_vq)				\
  46	do {							\
  47		if ((_vq)->last_add_time_valid) {		\
  48			WARN_ON(ktime_to_ms(ktime_sub(ktime_get(), \
  49				      (_vq)->last_add_time)) > 100); \
  50		}						\
  51	} while (0)
  52#define LAST_ADD_TIME_INVALID(_vq)				\
  53	((_vq)->last_add_time_valid = false)
  54#else
  55#define BAD_RING(_vq, fmt, args...)				\
  56	do {							\
  57		dev_err(&_vq->vq.vdev->dev,			\
  58			"%s:"fmt, (_vq)->vq.name, ##args);	\
  59		(_vq)->broken = true;				\
  60	} while (0)
  61#define START_USE(vq)
  62#define END_USE(vq)
  63#define LAST_ADD_TIME_UPDATE(vq)
  64#define LAST_ADD_TIME_CHECK(vq)
  65#define LAST_ADD_TIME_INVALID(vq)
  66#endif
  67
  68struct vring_desc_state_split {
  69	void *data;			/* Data for callback. */
  70	struct vring_desc *indir_desc;	/* Indirect descriptor, if any. */
  71};
  72
  73struct vring_desc_state_packed {
  74	void *data;			/* Data for callback. */
  75	struct vring_packed_desc *indir_desc; /* Indirect descriptor, if any. */
  76	u16 num;			/* Descriptor list length. */
  77	u16 next;			/* The next desc state in a list. */
  78	u16 last;			/* The last desc state in a list. */
  79};
  80
  81struct vring_desc_extra_packed {
  82	dma_addr_t addr;		/* Buffer DMA addr. */
  83	u32 len;			/* Buffer length. */
  84	u16 flags;			/* Descriptor flags. */
  85};
  86
  87struct vring_virtqueue {
  88	struct virtqueue vq;
  89
  90	/* Is this a packed ring? */
  91	bool packed_ring;
  92
  93	/* Is DMA API used? */
  94	bool use_dma_api;
  95
  96	/* Can we use weak barriers? */
  97	bool weak_barriers;
  98
  99	/* Other side has made a mess, don't try any more. */
 100	bool broken;
 101
 102	/* Host supports indirect buffers */
 103	bool indirect;
 104
 105	/* Host publishes avail event idx */
 106	bool event;
 107
 108	/* Head of free buffer list. */
 109	unsigned int free_head;
 110	/* Number we've added since last sync. */
 111	unsigned int num_added;
 112
 113	/* Last used index we've seen. */
 114	u16 last_used_idx;
 115
 116	union {
 117		/* Available for split ring */
 118		struct {
 119			/* Actual memory layout for this queue. */
 120			struct vring vring;
 121
 122			/* Last written value to avail->flags */
 123			u16 avail_flags_shadow;
 124
 125			/*
 126			 * Last written value to avail->idx in
 127			 * guest byte order.
 128			 */
 129			u16 avail_idx_shadow;
 130
 131			/* Per-descriptor state. */
 132			struct vring_desc_state_split *desc_state;
 133
 134			/* DMA address and size information */
 135			dma_addr_t queue_dma_addr;
 136			size_t queue_size_in_bytes;
 137		} split;
 138
 139		/* Available for packed ring */
 140		struct {
 141			/* Actual memory layout for this queue. */
 142			struct {
 143				unsigned int num;
 144				struct vring_packed_desc *desc;
 145				struct vring_packed_desc_event *driver;
 146				struct vring_packed_desc_event *device;
 147			} vring;
 148
 149			/* Driver ring wrap counter. */
 150			bool avail_wrap_counter;
 151
 152			/* Device ring wrap counter. */
 153			bool used_wrap_counter;
 154
 155			/* Avail used flags. */
 156			u16 avail_used_flags;
 157
 158			/* Index of the next avail descriptor. */
 159			u16 next_avail_idx;
 160
 161			/*
 162			 * Last written value to driver->flags in
 163			 * guest byte order.
 164			 */
 165			u16 event_flags_shadow;
 166
 167			/* Per-descriptor state. */
 168			struct vring_desc_state_packed *desc_state;
 169			struct vring_desc_extra_packed *desc_extra;
 170
 171			/* DMA address and size information */
 172			dma_addr_t ring_dma_addr;
 173			dma_addr_t driver_event_dma_addr;
 174			dma_addr_t device_event_dma_addr;
 175			size_t ring_size_in_bytes;
 176			size_t event_size_in_bytes;
 177		} packed;
 178	};
 179
 180	/* How to notify other side. FIXME: commonalize hcalls! */
 181	bool (*notify)(struct virtqueue *vq);
 182
 183	/* DMA, allocation, and size information */
 184	bool we_own_ring;
 
 
 185
 186#ifdef DEBUG
 187	/* They're supposed to lock for us. */
 188	unsigned int in_use;
 189
 190	/* Figure out if their kicks are too delayed. */
 191	bool last_add_time_valid;
 192	ktime_t last_add_time;
 193#endif
 194};
 195
 196
 197/*
 198 * Helpers.
 199 */
 200
 201#define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)
 202
 203static inline bool virtqueue_use_indirect(struct virtqueue *_vq,
 204					  unsigned int total_sg)
 205{
 206	struct vring_virtqueue *vq = to_vvq(_vq);
 207
 208	/*
 209	 * If the host supports indirect descriptor tables, and we have multiple
 210	 * buffers, then go indirect. FIXME: tune this threshold
 211	 */
 212	return (vq->indirect && total_sg > 1 && vq->vq.num_free);
 213}
 214
 215/*
 216 * Modern virtio devices have feature bits to specify whether they need a
 217 * quirk and bypass the IOMMU. If not there, just use the DMA API.
 218 *
 219 * If there, the interaction between virtio and DMA API is messy.
 220 *
 221 * On most systems with virtio, physical addresses match bus addresses,
 222 * and it doesn't particularly matter whether we use the DMA API.
 223 *
 224 * On some systems, including Xen and any system with a physical device
 225 * that speaks virtio behind a physical IOMMU, we must use the DMA API
 226 * for virtio DMA to work at all.
 227 *
 228 * On other systems, including SPARC and PPC64, virtio-pci devices are
 229 * enumerated as though they are behind an IOMMU, but the virtio host
 230 * ignores the IOMMU, so we must either pretend that the IOMMU isn't
 231 * there or somehow map everything as the identity.
 232 *
 233 * For the time being, we preserve historic behavior and bypass the DMA
 234 * API.
 235 *
 236 * TODO: install a per-device DMA ops structure that does the right thing
 237 * taking into account all the above quirks, and use the DMA API
 238 * unconditionally on data path.
 239 */
 240
 241static bool vring_use_dma_api(struct virtio_device *vdev)
 242{
 243	if (!virtio_has_dma_quirk(vdev))
 244		return true;
 245
 246	/* Otherwise, we are left to guess. */
 247	/*
 248	 * In theory, it's possible to have a buggy QEMU-supposed
 249	 * emulated Q35 IOMMU and Xen enabled at the same time.  On
 250	 * such a configuration, virtio has never worked and will
 251	 * not work without an even larger kludge.  Instead, enable
 252	 * the DMA API if we're a Xen guest, which at least allows
 253	 * all of the sensible Xen configurations to work correctly.
 254	 */
 255	if (xen_domain())
 256		return true;
 257
 258	return false;
 259}
 260
 261size_t virtio_max_dma_size(struct virtio_device *vdev)
 262{
 263	size_t max_segment_size = SIZE_MAX;
 264
 265	if (vring_use_dma_api(vdev))
 266		max_segment_size = dma_max_mapping_size(&vdev->dev);
 267
 268	return max_segment_size;
 269}
 270EXPORT_SYMBOL_GPL(virtio_max_dma_size);
 271
 272static void *vring_alloc_queue(struct virtio_device *vdev, size_t size,
 273			      dma_addr_t *dma_handle, gfp_t flag)
 274{
 275	if (vring_use_dma_api(vdev)) {
 276		return dma_alloc_coherent(vdev->dev.parent, size,
 277					  dma_handle, flag);
 278	} else {
 279		void *queue = alloc_pages_exact(PAGE_ALIGN(size), flag);
 280
 281		if (queue) {
 282			phys_addr_t phys_addr = virt_to_phys(queue);
 283			*dma_handle = (dma_addr_t)phys_addr;
 284
 285			/*
 286			 * Sanity check: make sure we dind't truncate
 287			 * the address.  The only arches I can find that
 288			 * have 64-bit phys_addr_t but 32-bit dma_addr_t
 289			 * are certain non-highmem MIPS and x86
 290			 * configurations, but these configurations
 291			 * should never allocate physical pages above 32
 292			 * bits, so this is fine.  Just in case, throw a
 293			 * warning and abort if we end up with an
 294			 * unrepresentable address.
 295			 */
 296			if (WARN_ON_ONCE(*dma_handle != phys_addr)) {
 297				free_pages_exact(queue, PAGE_ALIGN(size));
 298				return NULL;
 299			}
 300		}
 301		return queue;
 302	}
 303}
 304
 305static void vring_free_queue(struct virtio_device *vdev, size_t size,
 306			     void *queue, dma_addr_t dma_handle)
 307{
 308	if (vring_use_dma_api(vdev))
 309		dma_free_coherent(vdev->dev.parent, size, queue, dma_handle);
 310	else
 311		free_pages_exact(queue, PAGE_ALIGN(size));
 312}
 313
 314/*
 315 * The DMA ops on various arches are rather gnarly right now, and
 316 * making all of the arch DMA ops work on the vring device itself
 317 * is a mess.  For now, we use the parent device for DMA ops.
 318 */
 319static inline struct device *vring_dma_dev(const struct vring_virtqueue *vq)
 320{
 321	return vq->vq.vdev->dev.parent;
 322}
 323
 324/* Map one sg entry. */
 325static dma_addr_t vring_map_one_sg(const struct vring_virtqueue *vq,
 326				   struct scatterlist *sg,
 327				   enum dma_data_direction direction)
 328{
 329	if (!vq->use_dma_api)
 330		return (dma_addr_t)sg_phys(sg);
 331
 332	/*
 333	 * We can't use dma_map_sg, because we don't use scatterlists in
 334	 * the way it expects (we don't guarantee that the scatterlist
 335	 * will exist for the lifetime of the mapping).
 336	 */
 337	return dma_map_page(vring_dma_dev(vq),
 338			    sg_page(sg), sg->offset, sg->length,
 339			    direction);
 340}
 341
 342static dma_addr_t vring_map_single(const struct vring_virtqueue *vq,
 343				   void *cpu_addr, size_t size,
 344				   enum dma_data_direction direction)
 345{
 346	if (!vq->use_dma_api)
 347		return (dma_addr_t)virt_to_phys(cpu_addr);
 348
 349	return dma_map_single(vring_dma_dev(vq),
 350			      cpu_addr, size, direction);
 351}
 352
 353static int vring_mapping_error(const struct vring_virtqueue *vq,
 354			       dma_addr_t addr)
 355{
 356	if (!vq->use_dma_api)
 357		return 0;
 358
 359	return dma_mapping_error(vring_dma_dev(vq), addr);
 360}
 361
 362
 363/*
 364 * Split ring specific functions - *_split().
 365 */
 366
 367static void vring_unmap_one_split(const struct vring_virtqueue *vq,
 368				  struct vring_desc *desc)
 369{
 370	u16 flags;
 371
 372	if (!vq->use_dma_api)
 373		return;
 374
 375	flags = virtio16_to_cpu(vq->vq.vdev, desc->flags);
 376
 377	if (flags & VRING_DESC_F_INDIRECT) {
 378		dma_unmap_single(vring_dma_dev(vq),
 379				 virtio64_to_cpu(vq->vq.vdev, desc->addr),
 380				 virtio32_to_cpu(vq->vq.vdev, desc->len),
 381				 (flags & VRING_DESC_F_WRITE) ?
 382				 DMA_FROM_DEVICE : DMA_TO_DEVICE);
 383	} else {
 384		dma_unmap_page(vring_dma_dev(vq),
 385			       virtio64_to_cpu(vq->vq.vdev, desc->addr),
 386			       virtio32_to_cpu(vq->vq.vdev, desc->len),
 387			       (flags & VRING_DESC_F_WRITE) ?
 388			       DMA_FROM_DEVICE : DMA_TO_DEVICE);
 389	}
 390}
 391
 392static struct vring_desc *alloc_indirect_split(struct virtqueue *_vq,
 393					       unsigned int total_sg,
 394					       gfp_t gfp)
 
 
 
 
 
 
 
 
 395{
 396	struct vring_desc *desc;
 397	unsigned int i;
 398
 399	/*
 400	 * We require lowmem mappings for the descriptors because
 401	 * otherwise virt_to_phys will give us bogus addresses in the
 402	 * virtqueue.
 403	 */
 404	gfp &= ~__GFP_HIGHMEM;
 405
 406	desc = kmalloc_array(total_sg, sizeof(struct vring_desc), gfp);
 407	if (!desc)
 408		return NULL;
 409
 410	for (i = 0; i < total_sg; i++)
 411		desc[i].next = cpu_to_virtio16(_vq->vdev, i + 1);
 412	return desc;
 413}
 414
 415static inline int virtqueue_add_split(struct virtqueue *_vq,
 416				      struct scatterlist *sgs[],
 417				      unsigned int total_sg,
 418				      unsigned int out_sgs,
 419				      unsigned int in_sgs,
 420				      void *data,
 421				      void *ctx,
 422				      gfp_t gfp)
 423{
 424	struct vring_virtqueue *vq = to_vvq(_vq);
 425	struct scatterlist *sg;
 426	struct vring_desc *desc;
 427	unsigned int i, n, avail, descs_used, prev, err_idx;
 428	int head;
 429	bool indirect;
 430
 431	START_USE(vq);
 432
 433	BUG_ON(data == NULL);
 434	BUG_ON(ctx && vq->indirect);
 435
 436	if (unlikely(vq->broken)) {
 437		END_USE(vq);
 438		return -EIO;
 439	}
 440
 441	LAST_ADD_TIME_UPDATE(vq);
 
 
 
 
 
 
 
 
 
 
 
 442
 443	BUG_ON(total_sg == 0);
 444
 445	head = vq->free_head;
 446
 447	if (virtqueue_use_indirect(_vq, total_sg))
 448		desc = alloc_indirect_split(_vq, total_sg, gfp);
 
 
 449	else {
 450		desc = NULL;
 451		WARN_ON_ONCE(total_sg > vq->split.vring.num && !vq->indirect);
 452	}
 453
 454	if (desc) {
 455		/* Use a single buffer which doesn't continue */
 456		indirect = true;
 457		/* Set up rest to use this indirect table. */
 458		i = 0;
 459		descs_used = 1;
 460	} else {
 461		indirect = false;
 462		desc = vq->split.vring.desc;
 463		i = head;
 464		descs_used = total_sg;
 465	}
 466
 467	if (vq->vq.num_free < descs_used) {
 468		pr_debug("Can't add buf len %i - avail = %i\n",
 469			 descs_used, vq->vq.num_free);
 470		/* FIXME: for historical reasons, we force a notify here if
 471		 * there are outgoing parts to the buffer.  Presumably the
 472		 * host should service the ring ASAP. */
 473		if (out_sgs)
 474			vq->notify(&vq->vq);
 475		if (indirect)
 476			kfree(desc);
 477		END_USE(vq);
 478		return -ENOSPC;
 479	}
 480
 481	for (n = 0; n < out_sgs; n++) {
 482		for (sg = sgs[n]; sg; sg = sg_next(sg)) {
 483			dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_TO_DEVICE);
 484			if (vring_mapping_error(vq, addr))
 485				goto unmap_release;
 486
 487			desc[i].flags = cpu_to_virtio16(_vq->vdev, VRING_DESC_F_NEXT);
 488			desc[i].addr = cpu_to_virtio64(_vq->vdev, addr);
 489			desc[i].len = cpu_to_virtio32(_vq->vdev, sg->length);
 490			prev = i;
 491			i = virtio16_to_cpu(_vq->vdev, desc[i].next);
 492		}
 493	}
 494	for (; n < (out_sgs + in_sgs); n++) {
 495		for (sg = sgs[n]; sg; sg = sg_next(sg)) {
 496			dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_FROM_DEVICE);
 497			if (vring_mapping_error(vq, addr))
 498				goto unmap_release;
 499
 500			desc[i].flags = cpu_to_virtio16(_vq->vdev, VRING_DESC_F_NEXT | VRING_DESC_F_WRITE);
 501			desc[i].addr = cpu_to_virtio64(_vq->vdev, addr);
 502			desc[i].len = cpu_to_virtio32(_vq->vdev, sg->length);
 503			prev = i;
 504			i = virtio16_to_cpu(_vq->vdev, desc[i].next);
 505		}
 506	}
 507	/* Last one doesn't continue. */
 508	desc[prev].flags &= cpu_to_virtio16(_vq->vdev, ~VRING_DESC_F_NEXT);
 509
 510	if (indirect) {
 511		/* Now that the indirect table is filled in, map it. */
 512		dma_addr_t addr = vring_map_single(
 513			vq, desc, total_sg * sizeof(struct vring_desc),
 514			DMA_TO_DEVICE);
 515		if (vring_mapping_error(vq, addr))
 516			goto unmap_release;
 517
 518		vq->split.vring.desc[head].flags = cpu_to_virtio16(_vq->vdev,
 519				VRING_DESC_F_INDIRECT);
 520		vq->split.vring.desc[head].addr = cpu_to_virtio64(_vq->vdev,
 521				addr);
 522
 523		vq->split.vring.desc[head].len = cpu_to_virtio32(_vq->vdev,
 524				total_sg * sizeof(struct vring_desc));
 525	}
 526
 527	/* We're using some buffers from the free list. */
 528	vq->vq.num_free -= descs_used;
 529
 530	/* Update free pointer */
 531	if (indirect)
 532		vq->free_head = virtio16_to_cpu(_vq->vdev,
 533					vq->split.vring.desc[head].next);
 534	else
 535		vq->free_head = i;
 536
 537	/* Store token and indirect buffer state. */
 538	vq->split.desc_state[head].data = data;
 539	if (indirect)
 540		vq->split.desc_state[head].indir_desc = desc;
 541	else
 542		vq->split.desc_state[head].indir_desc = ctx;
 543
 544	/* Put entry in available array (but don't update avail->idx until they
 545	 * do sync). */
 546	avail = vq->split.avail_idx_shadow & (vq->split.vring.num - 1);
 547	vq->split.vring.avail->ring[avail] = cpu_to_virtio16(_vq->vdev, head);
 548
 549	/* Descriptors and available array need to be set before we expose the
 550	 * new available array entries. */
 551	virtio_wmb(vq->weak_barriers);
 552	vq->split.avail_idx_shadow++;
 553	vq->split.vring.avail->idx = cpu_to_virtio16(_vq->vdev,
 554						vq->split.avail_idx_shadow);
 555	vq->num_added++;
 556
 557	pr_debug("Added buffer head %i to %p\n", head, vq);
 558	END_USE(vq);
 559
 560	/* This is very unlikely, but theoretically possible.  Kick
 561	 * just in case. */
 562	if (unlikely(vq->num_added == (1 << 16) - 1))
 563		virtqueue_kick(_vq);
 564
 565	return 0;
 566
 567unmap_release:
 568	err_idx = i;
 569
 570	if (indirect)
 571		i = 0;
 572	else
 573		i = head;
 574
 575	for (n = 0; n < total_sg; n++) {
 576		if (i == err_idx)
 577			break;
 578		vring_unmap_one_split(vq, &desc[i]);
 579		i = virtio16_to_cpu(_vq->vdev, desc[i].next);
 580	}
 581
 582	if (indirect)
 583		kfree(desc);
 584
 585	END_USE(vq);
 586	return -ENOMEM;
 587}
 588
 589static bool virtqueue_kick_prepare_split(struct virtqueue *_vq)
 590{
 591	struct vring_virtqueue *vq = to_vvq(_vq);
 592	u16 new, old;
 593	bool needs_kick;
 594
 595	START_USE(vq);
 596	/* We need to expose available array entries before checking avail
 597	 * event. */
 598	virtio_mb(vq->weak_barriers);
 599
 600	old = vq->split.avail_idx_shadow - vq->num_added;
 601	new = vq->split.avail_idx_shadow;
 602	vq->num_added = 0;
 603
 604	LAST_ADD_TIME_CHECK(vq);
 605	LAST_ADD_TIME_INVALID(vq);
 606
 607	if (vq->event) {
 608		needs_kick = vring_need_event(virtio16_to_cpu(_vq->vdev,
 609					vring_avail_event(&vq->split.vring)),
 610					      new, old);
 611	} else {
 612		needs_kick = !(vq->split.vring.used->flags &
 613					cpu_to_virtio16(_vq->vdev,
 614						VRING_USED_F_NO_NOTIFY));
 615	}
 616	END_USE(vq);
 617	return needs_kick;
 618}
 619
 620static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head,
 621			     void **ctx)
 622{
 623	unsigned int i, j;
 624	__virtio16 nextflag = cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_NEXT);
 625
 626	/* Clear data ptr. */
 627	vq->split.desc_state[head].data = NULL;
 628
 629	/* Put back on free list: unmap first-level descriptors and find end */
 630	i = head;
 631
 632	while (vq->split.vring.desc[i].flags & nextflag) {
 633		vring_unmap_one_split(vq, &vq->split.vring.desc[i]);
 634		i = virtio16_to_cpu(vq->vq.vdev, vq->split.vring.desc[i].next);
 635		vq->vq.num_free++;
 636	}
 637
 638	vring_unmap_one_split(vq, &vq->split.vring.desc[i]);
 639	vq->split.vring.desc[i].next = cpu_to_virtio16(vq->vq.vdev,
 640						vq->free_head);
 641	vq->free_head = head;
 642
 643	/* Plus final descriptor */
 644	vq->vq.num_free++;
 645
 646	if (vq->indirect) {
 647		struct vring_desc *indir_desc =
 648				vq->split.desc_state[head].indir_desc;
 649		u32 len;
 650
 651		/* Free the indirect table, if any, now that it's unmapped. */
 652		if (!indir_desc)
 653			return;
 654
 655		len = virtio32_to_cpu(vq->vq.vdev,
 656				vq->split.vring.desc[head].len);
 657
 658		BUG_ON(!(vq->split.vring.desc[head].flags &
 659			 cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_INDIRECT)));
 660		BUG_ON(len == 0 || len % sizeof(struct vring_desc));
 661
 662		for (j = 0; j < len / sizeof(struct vring_desc); j++)
 663			vring_unmap_one_split(vq, &indir_desc[j]);
 664
 665		kfree(indir_desc);
 666		vq->split.desc_state[head].indir_desc = NULL;
 667	} else if (ctx) {
 668		*ctx = vq->split.desc_state[head].indir_desc;
 669	}
 670}
 671
 672static inline bool more_used_split(const struct vring_virtqueue *vq)
 673{
 674	return vq->last_used_idx != virtio16_to_cpu(vq->vq.vdev,
 675			vq->split.vring.used->idx);
 676}
 677
 678static void *virtqueue_get_buf_ctx_split(struct virtqueue *_vq,
 679					 unsigned int *len,
 680					 void **ctx)
 681{
 682	struct vring_virtqueue *vq = to_vvq(_vq);
 683	void *ret;
 684	unsigned int i;
 685	u16 last_used;
 686
 687	START_USE(vq);
 688
 689	if (unlikely(vq->broken)) {
 690		END_USE(vq);
 691		return NULL;
 692	}
 693
 694	if (!more_used_split(vq)) {
 695		pr_debug("No more buffers in queue\n");
 696		END_USE(vq);
 697		return NULL;
 698	}
 699
 700	/* Only get used array entries after they have been exposed by host. */
 701	virtio_rmb(vq->weak_barriers);
 702
 703	last_used = (vq->last_used_idx & (vq->split.vring.num - 1));
 704	i = virtio32_to_cpu(_vq->vdev,
 705			vq->split.vring.used->ring[last_used].id);
 706	*len = virtio32_to_cpu(_vq->vdev,
 707			vq->split.vring.used->ring[last_used].len);
 708
 709	if (unlikely(i >= vq->split.vring.num)) {
 710		BAD_RING(vq, "id %u out of range\n", i);
 711		return NULL;
 712	}
 713	if (unlikely(!vq->split.desc_state[i].data)) {
 714		BAD_RING(vq, "id %u is not a head!\n", i);
 715		return NULL;
 716	}
 717
 718	/* detach_buf_split clears data, so grab it now. */
 719	ret = vq->split.desc_state[i].data;
 720	detach_buf_split(vq, i, ctx);
 721	vq->last_used_idx++;
 722	/* If we expect an interrupt for the next entry, tell host
 723	 * by writing event index and flush out the write before
 724	 * the read in the next get_buf call. */
 725	if (!(vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT))
 726		virtio_store_mb(vq->weak_barriers,
 727				&vring_used_event(&vq->split.vring),
 728				cpu_to_virtio16(_vq->vdev, vq->last_used_idx));
 729
 730	LAST_ADD_TIME_INVALID(vq);
 731
 732	END_USE(vq);
 733	return ret;
 734}
 735
 736static void virtqueue_disable_cb_split(struct virtqueue *_vq)
 737{
 738	struct vring_virtqueue *vq = to_vvq(_vq);
 739
 740	if (!(vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) {
 741		vq->split.avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
 742		if (!vq->event)
 743			vq->split.vring.avail->flags =
 744				cpu_to_virtio16(_vq->vdev,
 745						vq->split.avail_flags_shadow);
 746	}
 747}
 748
 749static unsigned virtqueue_enable_cb_prepare_split(struct virtqueue *_vq)
 750{
 751	struct vring_virtqueue *vq = to_vvq(_vq);
 752	u16 last_used_idx;
 753
 754	START_USE(vq);
 755
 756	/* We optimistically turn back on interrupts, then check if there was
 757	 * more to do. */
 758	/* Depending on the VIRTIO_RING_F_EVENT_IDX feature, we need to
 759	 * either clear the flags bit or point the event index at the next
 760	 * entry. Always do both to keep code simple. */
 761	if (vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT) {
 762		vq->split.avail_flags_shadow &= ~VRING_AVAIL_F_NO_INTERRUPT;
 763		if (!vq->event)
 764			vq->split.vring.avail->flags =
 765				cpu_to_virtio16(_vq->vdev,
 766						vq->split.avail_flags_shadow);
 767	}
 768	vring_used_event(&vq->split.vring) = cpu_to_virtio16(_vq->vdev,
 769			last_used_idx = vq->last_used_idx);
 770	END_USE(vq);
 771	return last_used_idx;
 772}
 773
 774static bool virtqueue_poll_split(struct virtqueue *_vq, unsigned last_used_idx)
 775{
 776	struct vring_virtqueue *vq = to_vvq(_vq);
 777
 778	return (u16)last_used_idx != virtio16_to_cpu(_vq->vdev,
 779			vq->split.vring.used->idx);
 780}
 781
 782static bool virtqueue_enable_cb_delayed_split(struct virtqueue *_vq)
 783{
 784	struct vring_virtqueue *vq = to_vvq(_vq);
 785	u16 bufs;
 786
 787	START_USE(vq);
 788
 789	/* We optimistically turn back on interrupts, then check if there was
 790	 * more to do. */
 791	/* Depending on the VIRTIO_RING_F_USED_EVENT_IDX feature, we need to
 792	 * either clear the flags bit or point the event index at the next
 793	 * entry. Always update the event index to keep code simple. */
 794	if (vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT) {
 795		vq->split.avail_flags_shadow &= ~VRING_AVAIL_F_NO_INTERRUPT;
 796		if (!vq->event)
 797			vq->split.vring.avail->flags =
 798				cpu_to_virtio16(_vq->vdev,
 799						vq->split.avail_flags_shadow);
 800	}
 801	/* TODO: tune this threshold */
 802	bufs = (u16)(vq->split.avail_idx_shadow - vq->last_used_idx) * 3 / 4;
 803
 804	virtio_store_mb(vq->weak_barriers,
 805			&vring_used_event(&vq->split.vring),
 806			cpu_to_virtio16(_vq->vdev, vq->last_used_idx + bufs));
 807
 808	if (unlikely((u16)(virtio16_to_cpu(_vq->vdev, vq->split.vring.used->idx)
 809					- vq->last_used_idx) > bufs)) {
 810		END_USE(vq);
 811		return false;
 812	}
 813
 814	END_USE(vq);
 815	return true;
 816}
 817
 818static void *virtqueue_detach_unused_buf_split(struct virtqueue *_vq)
 819{
 820	struct vring_virtqueue *vq = to_vvq(_vq);
 821	unsigned int i;
 822	void *buf;
 823
 824	START_USE(vq);
 825
 826	for (i = 0; i < vq->split.vring.num; i++) {
 827		if (!vq->split.desc_state[i].data)
 828			continue;
 829		/* detach_buf_split clears data, so grab it now. */
 830		buf = vq->split.desc_state[i].data;
 831		detach_buf_split(vq, i, NULL);
 832		vq->split.avail_idx_shadow--;
 833		vq->split.vring.avail->idx = cpu_to_virtio16(_vq->vdev,
 834				vq->split.avail_idx_shadow);
 835		END_USE(vq);
 836		return buf;
 837	}
 838	/* That should have freed everything. */
 839	BUG_ON(vq->vq.num_free != vq->split.vring.num);
 840
 841	END_USE(vq);
 842	return NULL;
 843}
 844
 845static struct virtqueue *vring_create_virtqueue_split(
 846	unsigned int index,
 847	unsigned int num,
 848	unsigned int vring_align,
 849	struct virtio_device *vdev,
 850	bool weak_barriers,
 851	bool may_reduce_num,
 852	bool context,
 853	bool (*notify)(struct virtqueue *),
 854	void (*callback)(struct virtqueue *),
 855	const char *name)
 856{
 857	struct virtqueue *vq;
 858	void *queue = NULL;
 859	dma_addr_t dma_addr;
 860	size_t queue_size_in_bytes;
 861	struct vring vring;
 862
 863	/* We assume num is a power of 2. */
 864	if (num & (num - 1)) {
 865		dev_warn(&vdev->dev, "Bad virtqueue length %u\n", num);
 866		return NULL;
 867	}
 868
 869	/* TODO: allocate each queue chunk individually */
 870	for (; num && vring_size(num, vring_align) > PAGE_SIZE; num /= 2) {
 871		queue = vring_alloc_queue(vdev, vring_size(num, vring_align),
 872					  &dma_addr,
 873					  GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
 874		if (queue)
 875			break;
 876		if (!may_reduce_num)
 877			return NULL;
 878	}
 879
 880	if (!num)
 881		return NULL;
 882
 883	if (!queue) {
 884		/* Try to get a single page. You are my only hope! */
 885		queue = vring_alloc_queue(vdev, vring_size(num, vring_align),
 886					  &dma_addr, GFP_KERNEL|__GFP_ZERO);
 887	}
 888	if (!queue)
 889		return NULL;
 890
 891	queue_size_in_bytes = vring_size(num, vring_align);
 892	vring_init(&vring, num, queue, vring_align);
 893
 894	vq = __vring_new_virtqueue(index, vring, vdev, weak_barriers, context,
 895				   notify, callback, name);
 896	if (!vq) {
 897		vring_free_queue(vdev, queue_size_in_bytes, queue,
 898				 dma_addr);
 899		return NULL;
 900	}
 901
 902	to_vvq(vq)->split.queue_dma_addr = dma_addr;
 903	to_vvq(vq)->split.queue_size_in_bytes = queue_size_in_bytes;
 904	to_vvq(vq)->we_own_ring = true;
 905
 906	return vq;
 907}
 908
 909
 910/*
 911 * Packed ring specific functions - *_packed().
 912 */
 913
 914static void vring_unmap_state_packed(const struct vring_virtqueue *vq,
 915				     struct vring_desc_extra_packed *state)
 916{
 917	u16 flags;
 918
 919	if (!vq->use_dma_api)
 920		return;
 921
 922	flags = state->flags;
 923
 924	if (flags & VRING_DESC_F_INDIRECT) {
 925		dma_unmap_single(vring_dma_dev(vq),
 926				 state->addr, state->len,
 927				 (flags & VRING_DESC_F_WRITE) ?
 928				 DMA_FROM_DEVICE : DMA_TO_DEVICE);
 929	} else {
 930		dma_unmap_page(vring_dma_dev(vq),
 931			       state->addr, state->len,
 932			       (flags & VRING_DESC_F_WRITE) ?
 933			       DMA_FROM_DEVICE : DMA_TO_DEVICE);
 934	}
 935}
 936
 937static void vring_unmap_desc_packed(const struct vring_virtqueue *vq,
 938				   struct vring_packed_desc *desc)
 939{
 940	u16 flags;
 941
 942	if (!vq->use_dma_api)
 943		return;
 944
 945	flags = le16_to_cpu(desc->flags);
 946
 947	if (flags & VRING_DESC_F_INDIRECT) {
 948		dma_unmap_single(vring_dma_dev(vq),
 949				 le64_to_cpu(desc->addr),
 950				 le32_to_cpu(desc->len),
 951				 (flags & VRING_DESC_F_WRITE) ?
 952				 DMA_FROM_DEVICE : DMA_TO_DEVICE);
 953	} else {
 954		dma_unmap_page(vring_dma_dev(vq),
 955			       le64_to_cpu(desc->addr),
 956			       le32_to_cpu(desc->len),
 957			       (flags & VRING_DESC_F_WRITE) ?
 958			       DMA_FROM_DEVICE : DMA_TO_DEVICE);
 959	}
 960}
 961
 962static struct vring_packed_desc *alloc_indirect_packed(unsigned int total_sg,
 963						       gfp_t gfp)
 964{
 965	struct vring_packed_desc *desc;
 966
 967	/*
 968	 * We require lowmem mappings for the descriptors because
 969	 * otherwise virt_to_phys will give us bogus addresses in the
 970	 * virtqueue.
 971	 */
 972	gfp &= ~__GFP_HIGHMEM;
 973
 974	desc = kmalloc_array(total_sg, sizeof(struct vring_packed_desc), gfp);
 975
 976	return desc;
 977}
 978
 979static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
 980				       struct scatterlist *sgs[],
 981				       unsigned int total_sg,
 982				       unsigned int out_sgs,
 983				       unsigned int in_sgs,
 984				       void *data,
 985				       gfp_t gfp)
 986{
 987	struct vring_packed_desc *desc;
 988	struct scatterlist *sg;
 989	unsigned int i, n, err_idx;
 990	u16 head, id;
 991	dma_addr_t addr;
 992
 993	head = vq->packed.next_avail_idx;
 994	desc = alloc_indirect_packed(total_sg, gfp);
 995
 996	if (unlikely(vq->vq.num_free < 1)) {
 997		pr_debug("Can't add buf len 1 - avail = 0\n");
 998		kfree(desc);
 999		END_USE(vq);
1000		return -ENOSPC;
1001	}
1002
1003	i = 0;
1004	id = vq->free_head;
1005	BUG_ON(id == vq->packed.vring.num);
1006
1007	for (n = 0; n < out_sgs + in_sgs; n++) {
1008		for (sg = sgs[n]; sg; sg = sg_next(sg)) {
1009			addr = vring_map_one_sg(vq, sg, n < out_sgs ?
1010					DMA_TO_DEVICE : DMA_FROM_DEVICE);
1011			if (vring_mapping_error(vq, addr))
1012				goto unmap_release;
1013
1014			desc[i].flags = cpu_to_le16(n < out_sgs ?
1015						0 : VRING_DESC_F_WRITE);
1016			desc[i].addr = cpu_to_le64(addr);
1017			desc[i].len = cpu_to_le32(sg->length);
1018			i++;
1019		}
1020	}
1021
1022	/* Now that the indirect table is filled in, map it. */
1023	addr = vring_map_single(vq, desc,
1024			total_sg * sizeof(struct vring_packed_desc),
1025			DMA_TO_DEVICE);
1026	if (vring_mapping_error(vq, addr))
1027		goto unmap_release;
1028
1029	vq->packed.vring.desc[head].addr = cpu_to_le64(addr);
1030	vq->packed.vring.desc[head].len = cpu_to_le32(total_sg *
1031				sizeof(struct vring_packed_desc));
1032	vq->packed.vring.desc[head].id = cpu_to_le16(id);
1033
1034	if (vq->use_dma_api) {
1035		vq->packed.desc_extra[id].addr = addr;
1036		vq->packed.desc_extra[id].len = total_sg *
1037				sizeof(struct vring_packed_desc);
1038		vq->packed.desc_extra[id].flags = VRING_DESC_F_INDIRECT |
1039						  vq->packed.avail_used_flags;
1040	}
1041
1042	/*
1043	 * A driver MUST NOT make the first descriptor in the list
1044	 * available before all subsequent descriptors comprising
1045	 * the list are made available.
1046	 */
1047	virtio_wmb(vq->weak_barriers);
1048	vq->packed.vring.desc[head].flags = cpu_to_le16(VRING_DESC_F_INDIRECT |
1049						vq->packed.avail_used_flags);
1050
1051	/* We're using some buffers from the free list. */
1052	vq->vq.num_free -= 1;
1053
1054	/* Update free pointer */
1055	n = head + 1;
1056	if (n >= vq->packed.vring.num) {
1057		n = 0;
1058		vq->packed.avail_wrap_counter ^= 1;
1059		vq->packed.avail_used_flags ^=
1060				1 << VRING_PACKED_DESC_F_AVAIL |
1061				1 << VRING_PACKED_DESC_F_USED;
1062	}
1063	vq->packed.next_avail_idx = n;
1064	vq->free_head = vq->packed.desc_state[id].next;
1065
1066	/* Store token and indirect buffer state. */
1067	vq->packed.desc_state[id].num = 1;
1068	vq->packed.desc_state[id].data = data;
1069	vq->packed.desc_state[id].indir_desc = desc;
1070	vq->packed.desc_state[id].last = id;
1071
1072	vq->num_added += 1;
1073
1074	pr_debug("Added buffer head %i to %p\n", head, vq);
1075	END_USE(vq);
1076
1077	return 0;
1078
1079unmap_release:
1080	err_idx = i;
1081
1082	for (i = 0; i < err_idx; i++)
1083		vring_unmap_desc_packed(vq, &desc[i]);
1084
1085	kfree(desc);
1086
1087	END_USE(vq);
1088	return -ENOMEM;
1089}
1090
1091static inline int virtqueue_add_packed(struct virtqueue *_vq,
1092				       struct scatterlist *sgs[],
1093				       unsigned int total_sg,
1094				       unsigned int out_sgs,
1095				       unsigned int in_sgs,
1096				       void *data,
1097				       void *ctx,
1098				       gfp_t gfp)
1099{
1100	struct vring_virtqueue *vq = to_vvq(_vq);
1101	struct vring_packed_desc *desc;
1102	struct scatterlist *sg;
1103	unsigned int i, n, c, descs_used, err_idx;
1104	__le16 head_flags, flags;
1105	u16 head, id, prev, curr, avail_used_flags;
1106
1107	START_USE(vq);
1108
1109	BUG_ON(data == NULL);
1110	BUG_ON(ctx && vq->indirect);
1111
1112	if (unlikely(vq->broken)) {
1113		END_USE(vq);
1114		return -EIO;
1115	}
1116
1117	LAST_ADD_TIME_UPDATE(vq);
1118
1119	BUG_ON(total_sg == 0);
1120
1121	if (virtqueue_use_indirect(_vq, total_sg))
1122		return virtqueue_add_indirect_packed(vq, sgs, total_sg,
1123				out_sgs, in_sgs, data, gfp);
1124
1125	head = vq->packed.next_avail_idx;
1126	avail_used_flags = vq->packed.avail_used_flags;
1127
1128	WARN_ON_ONCE(total_sg > vq->packed.vring.num && !vq->indirect);
1129
1130	desc = vq->packed.vring.desc;
1131	i = head;
1132	descs_used = total_sg;
1133
1134	if (unlikely(vq->vq.num_free < descs_used)) {
1135		pr_debug("Can't add buf len %i - avail = %i\n",
1136			 descs_used, vq->vq.num_free);
1137		END_USE(vq);
1138		return -ENOSPC;
1139	}
1140
1141	id = vq->free_head;
1142	BUG_ON(id == vq->packed.vring.num);
1143
1144	curr = id;
1145	c = 0;
1146	for (n = 0; n < out_sgs + in_sgs; n++) {
1147		for (sg = sgs[n]; sg; sg = sg_next(sg)) {
1148			dma_addr_t addr = vring_map_one_sg(vq, sg, n < out_sgs ?
1149					DMA_TO_DEVICE : DMA_FROM_DEVICE);
1150			if (vring_mapping_error(vq, addr))
1151				goto unmap_release;
1152
1153			flags = cpu_to_le16(vq->packed.avail_used_flags |
1154				    (++c == total_sg ? 0 : VRING_DESC_F_NEXT) |
1155				    (n < out_sgs ? 0 : VRING_DESC_F_WRITE));
1156			if (i == head)
1157				head_flags = flags;
1158			else
1159				desc[i].flags = flags;
1160
1161			desc[i].addr = cpu_to_le64(addr);
1162			desc[i].len = cpu_to_le32(sg->length);
1163			desc[i].id = cpu_to_le16(id);
1164
1165			if (unlikely(vq->use_dma_api)) {
1166				vq->packed.desc_extra[curr].addr = addr;
1167				vq->packed.desc_extra[curr].len = sg->length;
1168				vq->packed.desc_extra[curr].flags =
1169					le16_to_cpu(flags);
1170			}
1171			prev = curr;
1172			curr = vq->packed.desc_state[curr].next;
1173
1174			if ((unlikely(++i >= vq->packed.vring.num))) {
1175				i = 0;
1176				vq->packed.avail_used_flags ^=
1177					1 << VRING_PACKED_DESC_F_AVAIL |
1178					1 << VRING_PACKED_DESC_F_USED;
1179			}
1180		}
1181	}
1182
1183	if (i < head)
1184		vq->packed.avail_wrap_counter ^= 1;
1185
1186	/* We're using some buffers from the free list. */
1187	vq->vq.num_free -= descs_used;
1188
1189	/* Update free pointer */
1190	vq->packed.next_avail_idx = i;
1191	vq->free_head = curr;
1192
1193	/* Store token. */
1194	vq->packed.desc_state[id].num = descs_used;
1195	vq->packed.desc_state[id].data = data;
1196	vq->packed.desc_state[id].indir_desc = ctx;
1197	vq->packed.desc_state[id].last = prev;
1198
1199	/*
1200	 * A driver MUST NOT make the first descriptor in the list
1201	 * available before all subsequent descriptors comprising
1202	 * the list are made available.
1203	 */
1204	virtio_wmb(vq->weak_barriers);
1205	vq->packed.vring.desc[head].flags = head_flags;
1206	vq->num_added += descs_used;
1207
1208	pr_debug("Added buffer head %i to %p\n", head, vq);
1209	END_USE(vq);
1210
1211	return 0;
1212
1213unmap_release:
1214	err_idx = i;
1215	i = head;
1216
1217	vq->packed.avail_used_flags = avail_used_flags;
1218
1219	for (n = 0; n < total_sg; n++) {
1220		if (i == err_idx)
1221			break;
1222		vring_unmap_desc_packed(vq, &desc[i]);
1223		i++;
1224		if (i >= vq->packed.vring.num)
1225			i = 0;
1226	}
1227
1228	END_USE(vq);
1229	return -EIO;
1230}
1231
1232static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq)
1233{
1234	struct vring_virtqueue *vq = to_vvq(_vq);
1235	u16 new, old, off_wrap, flags, wrap_counter, event_idx;
1236	bool needs_kick;
1237	union {
1238		struct {
1239			__le16 off_wrap;
1240			__le16 flags;
1241		};
1242		u32 u32;
1243	} snapshot;
1244
1245	START_USE(vq);
1246
1247	/*
1248	 * We need to expose the new flags value before checking notification
1249	 * suppressions.
1250	 */
1251	virtio_mb(vq->weak_barriers);
1252
1253	old = vq->packed.next_avail_idx - vq->num_added;
1254	new = vq->packed.next_avail_idx;
1255	vq->num_added = 0;
1256
1257	snapshot.u32 = *(u32 *)vq->packed.vring.device;
1258	flags = le16_to_cpu(snapshot.flags);
1259
1260	LAST_ADD_TIME_CHECK(vq);
1261	LAST_ADD_TIME_INVALID(vq);
1262
1263	if (flags != VRING_PACKED_EVENT_FLAG_DESC) {
1264		needs_kick = (flags != VRING_PACKED_EVENT_FLAG_DISABLE);
1265		goto out;
1266	}
1267
1268	off_wrap = le16_to_cpu(snapshot.off_wrap);
1269
1270	wrap_counter = off_wrap >> VRING_PACKED_EVENT_F_WRAP_CTR;
1271	event_idx = off_wrap & ~(1 << VRING_PACKED_EVENT_F_WRAP_CTR);
1272	if (wrap_counter != vq->packed.avail_wrap_counter)
1273		event_idx -= vq->packed.vring.num;
1274
1275	needs_kick = vring_need_event(event_idx, new, old);
1276out:
1277	END_USE(vq);
1278	return needs_kick;
1279}
1280
1281static void detach_buf_packed(struct vring_virtqueue *vq,
1282			      unsigned int id, void **ctx)
1283{
1284	struct vring_desc_state_packed *state = NULL;
1285	struct vring_packed_desc *desc;
1286	unsigned int i, curr;
1287
1288	state = &vq->packed.desc_state[id];
1289
1290	/* Clear data ptr. */
1291	state->data = NULL;
1292
1293	vq->packed.desc_state[state->last].next = vq->free_head;
1294	vq->free_head = id;
1295	vq->vq.num_free += state->num;
1296
1297	if (unlikely(vq->use_dma_api)) {
1298		curr = id;
1299		for (i = 0; i < state->num; i++) {
1300			vring_unmap_state_packed(vq,
1301				&vq->packed.desc_extra[curr]);
1302			curr = vq->packed.desc_state[curr].next;
1303		}
1304	}
1305
1306	if (vq->indirect) {
1307		u32 len;
1308
1309		/* Free the indirect table, if any, now that it's unmapped. */
1310		desc = state->indir_desc;
1311		if (!desc)
1312			return;
1313
1314		if (vq->use_dma_api) {
1315			len = vq->packed.desc_extra[id].len;
1316			for (i = 0; i < len / sizeof(struct vring_packed_desc);
1317					i++)
1318				vring_unmap_desc_packed(vq, &desc[i]);
1319		}
1320		kfree(desc);
1321		state->indir_desc = NULL;
1322	} else if (ctx) {
1323		*ctx = state->indir_desc;
1324	}
1325}
1326
1327static inline bool is_used_desc_packed(const struct vring_virtqueue *vq,
1328				       u16 idx, bool used_wrap_counter)
1329{
1330	bool avail, used;
1331	u16 flags;
1332
1333	flags = le16_to_cpu(vq->packed.vring.desc[idx].flags);
1334	avail = !!(flags & (1 << VRING_PACKED_DESC_F_AVAIL));
1335	used = !!(flags & (1 << VRING_PACKED_DESC_F_USED));
1336
1337	return avail == used && used == used_wrap_counter;
1338}
1339
1340static inline bool more_used_packed(const struct vring_virtqueue *vq)
1341{
1342	return is_used_desc_packed(vq, vq->last_used_idx,
1343			vq->packed.used_wrap_counter);
1344}
1345
1346static void *virtqueue_get_buf_ctx_packed(struct virtqueue *_vq,
1347					  unsigned int *len,
1348					  void **ctx)
1349{
1350	struct vring_virtqueue *vq = to_vvq(_vq);
1351	u16 last_used, id;
1352	void *ret;
1353
1354	START_USE(vq);
1355
1356	if (unlikely(vq->broken)) {
1357		END_USE(vq);
1358		return NULL;
1359	}
1360
1361	if (!more_used_packed(vq)) {
1362		pr_debug("No more buffers in queue\n");
1363		END_USE(vq);
1364		return NULL;
1365	}
1366
1367	/* Only get used elements after they have been exposed by host. */
1368	virtio_rmb(vq->weak_barriers);
1369
1370	last_used = vq->last_used_idx;
1371	id = le16_to_cpu(vq->packed.vring.desc[last_used].id);
1372	*len = le32_to_cpu(vq->packed.vring.desc[last_used].len);
1373
1374	if (unlikely(id >= vq->packed.vring.num)) {
1375		BAD_RING(vq, "id %u out of range\n", id);
1376		return NULL;
1377	}
1378	if (unlikely(!vq->packed.desc_state[id].data)) {
1379		BAD_RING(vq, "id %u is not a head!\n", id);
1380		return NULL;
1381	}
1382
1383	/* detach_buf_packed clears data, so grab it now. */
1384	ret = vq->packed.desc_state[id].data;
1385	detach_buf_packed(vq, id, ctx);
1386
1387	vq->last_used_idx += vq->packed.desc_state[id].num;
1388	if (unlikely(vq->last_used_idx >= vq->packed.vring.num)) {
1389		vq->last_used_idx -= vq->packed.vring.num;
1390		vq->packed.used_wrap_counter ^= 1;
1391	}
1392
1393	/*
1394	 * If we expect an interrupt for the next entry, tell host
1395	 * by writing event index and flush out the write before
1396	 * the read in the next get_buf call.
1397	 */
1398	if (vq->packed.event_flags_shadow == VRING_PACKED_EVENT_FLAG_DESC)
1399		virtio_store_mb(vq->weak_barriers,
1400				&vq->packed.vring.driver->off_wrap,
1401				cpu_to_le16(vq->last_used_idx |
1402					(vq->packed.used_wrap_counter <<
1403					 VRING_PACKED_EVENT_F_WRAP_CTR)));
1404
1405	LAST_ADD_TIME_INVALID(vq);
1406
1407	END_USE(vq);
1408	return ret;
1409}
1410
1411static void virtqueue_disable_cb_packed(struct virtqueue *_vq)
1412{
1413	struct vring_virtqueue *vq = to_vvq(_vq);
1414
1415	if (vq->packed.event_flags_shadow != VRING_PACKED_EVENT_FLAG_DISABLE) {
1416		vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_DISABLE;
1417		vq->packed.vring.driver->flags =
1418			cpu_to_le16(vq->packed.event_flags_shadow);
1419	}
1420}
1421
1422static unsigned virtqueue_enable_cb_prepare_packed(struct virtqueue *_vq)
1423{
1424	struct vring_virtqueue *vq = to_vvq(_vq);
1425
1426	START_USE(vq);
1427
1428	/*
1429	 * We optimistically turn back on interrupts, then check if there was
1430	 * more to do.
1431	 */
1432
1433	if (vq->event) {
1434		vq->packed.vring.driver->off_wrap =
1435			cpu_to_le16(vq->last_used_idx |
1436				(vq->packed.used_wrap_counter <<
1437				 VRING_PACKED_EVENT_F_WRAP_CTR));
1438		/*
1439		 * We need to update event offset and event wrap
1440		 * counter first before updating event flags.
1441		 */
1442		virtio_wmb(vq->weak_barriers);
1443	}
1444
1445	if (vq->packed.event_flags_shadow == VRING_PACKED_EVENT_FLAG_DISABLE) {
1446		vq->packed.event_flags_shadow = vq->event ?
1447				VRING_PACKED_EVENT_FLAG_DESC :
1448				VRING_PACKED_EVENT_FLAG_ENABLE;
1449		vq->packed.vring.driver->flags =
1450				cpu_to_le16(vq->packed.event_flags_shadow);
1451	}
1452
1453	END_USE(vq);
1454	return vq->last_used_idx | ((u16)vq->packed.used_wrap_counter <<
1455			VRING_PACKED_EVENT_F_WRAP_CTR);
1456}
1457
1458static bool virtqueue_poll_packed(struct virtqueue *_vq, u16 off_wrap)
1459{
1460	struct vring_virtqueue *vq = to_vvq(_vq);
1461	bool wrap_counter;
1462	u16 used_idx;
1463
1464	wrap_counter = off_wrap >> VRING_PACKED_EVENT_F_WRAP_CTR;
1465	used_idx = off_wrap & ~(1 << VRING_PACKED_EVENT_F_WRAP_CTR);
1466
1467	return is_used_desc_packed(vq, used_idx, wrap_counter);
1468}
1469
1470static bool virtqueue_enable_cb_delayed_packed(struct virtqueue *_vq)
1471{
1472	struct vring_virtqueue *vq = to_vvq(_vq);
1473	u16 used_idx, wrap_counter;
1474	u16 bufs;
1475
1476	START_USE(vq);
1477
1478	/*
1479	 * We optimistically turn back on interrupts, then check if there was
1480	 * more to do.
1481	 */
1482
1483	if (vq->event) {
1484		/* TODO: tune this threshold */
1485		bufs = (vq->packed.vring.num - vq->vq.num_free) * 3 / 4;
1486		wrap_counter = vq->packed.used_wrap_counter;
1487
1488		used_idx = vq->last_used_idx + bufs;
1489		if (used_idx >= vq->packed.vring.num) {
1490			used_idx -= vq->packed.vring.num;
1491			wrap_counter ^= 1;
1492		}
1493
1494		vq->packed.vring.driver->off_wrap = cpu_to_le16(used_idx |
1495			(wrap_counter << VRING_PACKED_EVENT_F_WRAP_CTR));
1496
1497		/*
1498		 * We need to update event offset and event wrap
1499		 * counter first before updating event flags.
1500		 */
1501		virtio_wmb(vq->weak_barriers);
1502	}
1503
1504	if (vq->packed.event_flags_shadow == VRING_PACKED_EVENT_FLAG_DISABLE) {
1505		vq->packed.event_flags_shadow = vq->event ?
1506				VRING_PACKED_EVENT_FLAG_DESC :
1507				VRING_PACKED_EVENT_FLAG_ENABLE;
1508		vq->packed.vring.driver->flags =
1509				cpu_to_le16(vq->packed.event_flags_shadow);
1510	}
1511
1512	/*
1513	 * We need to update event suppression structure first
1514	 * before re-checking for more used buffers.
1515	 */
1516	virtio_mb(vq->weak_barriers);
1517
1518	if (is_used_desc_packed(vq,
1519				vq->last_used_idx,
1520				vq->packed.used_wrap_counter)) {
1521		END_USE(vq);
1522		return false;
1523	}
1524
1525	END_USE(vq);
1526	return true;
1527}
1528
1529static void *virtqueue_detach_unused_buf_packed(struct virtqueue *_vq)
1530{
1531	struct vring_virtqueue *vq = to_vvq(_vq);
1532	unsigned int i;
1533	void *buf;
1534
1535	START_USE(vq);
1536
1537	for (i = 0; i < vq->packed.vring.num; i++) {
1538		if (!vq->packed.desc_state[i].data)
1539			continue;
1540		/* detach_buf clears data, so grab it now. */
1541		buf = vq->packed.desc_state[i].data;
1542		detach_buf_packed(vq, i, NULL);
1543		END_USE(vq);
1544		return buf;
1545	}
1546	/* That should have freed everything. */
1547	BUG_ON(vq->vq.num_free != vq->packed.vring.num);
1548
1549	END_USE(vq);
1550	return NULL;
1551}
1552
1553static struct virtqueue *vring_create_virtqueue_packed(
1554	unsigned int index,
1555	unsigned int num,
1556	unsigned int vring_align,
1557	struct virtio_device *vdev,
1558	bool weak_barriers,
1559	bool may_reduce_num,
1560	bool context,
1561	bool (*notify)(struct virtqueue *),
1562	void (*callback)(struct virtqueue *),
1563	const char *name)
1564{
1565	struct vring_virtqueue *vq;
1566	struct vring_packed_desc *ring;
1567	struct vring_packed_desc_event *driver, *device;
1568	dma_addr_t ring_dma_addr, driver_event_dma_addr, device_event_dma_addr;
1569	size_t ring_size_in_bytes, event_size_in_bytes;
1570	unsigned int i;
1571
1572	ring_size_in_bytes = num * sizeof(struct vring_packed_desc);
1573
1574	ring = vring_alloc_queue(vdev, ring_size_in_bytes,
1575				 &ring_dma_addr,
1576				 GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
1577	if (!ring)
1578		goto err_ring;
1579
1580	event_size_in_bytes = sizeof(struct vring_packed_desc_event);
1581
1582	driver = vring_alloc_queue(vdev, event_size_in_bytes,
1583				   &driver_event_dma_addr,
1584				   GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
1585	if (!driver)
1586		goto err_driver;
1587
1588	device = vring_alloc_queue(vdev, event_size_in_bytes,
1589				   &device_event_dma_addr,
1590				   GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
1591	if (!device)
1592		goto err_device;
1593
1594	vq = kmalloc(sizeof(*vq), GFP_KERNEL);
1595	if (!vq)
1596		goto err_vq;
1597
1598	vq->vq.callback = callback;
1599	vq->vq.vdev = vdev;
1600	vq->vq.name = name;
1601	vq->vq.num_free = num;
1602	vq->vq.index = index;
1603	vq->we_own_ring = true;
1604	vq->notify = notify;
1605	vq->weak_barriers = weak_barriers;
1606	vq->broken = false;
1607	vq->last_used_idx = 0;
1608	vq->num_added = 0;
1609	vq->packed_ring = true;
1610	vq->use_dma_api = vring_use_dma_api(vdev);
1611	list_add_tail(&vq->vq.list, &vdev->vqs);
1612#ifdef DEBUG
1613	vq->in_use = false;
1614	vq->last_add_time_valid = false;
1615#endif
1616
1617	vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) &&
1618		!context;
1619	vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
1620
1621	if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM))
1622		vq->weak_barriers = false;
1623
1624	vq->packed.ring_dma_addr = ring_dma_addr;
1625	vq->packed.driver_event_dma_addr = driver_event_dma_addr;
1626	vq->packed.device_event_dma_addr = device_event_dma_addr;
1627
1628	vq->packed.ring_size_in_bytes = ring_size_in_bytes;
1629	vq->packed.event_size_in_bytes = event_size_in_bytes;
1630
1631	vq->packed.vring.num = num;
1632	vq->packed.vring.desc = ring;
1633	vq->packed.vring.driver = driver;
1634	vq->packed.vring.device = device;
1635
1636	vq->packed.next_avail_idx = 0;
1637	vq->packed.avail_wrap_counter = 1;
1638	vq->packed.used_wrap_counter = 1;
1639	vq->packed.event_flags_shadow = 0;
1640	vq->packed.avail_used_flags = 1 << VRING_PACKED_DESC_F_AVAIL;
1641
1642	vq->packed.desc_state = kmalloc_array(num,
1643			sizeof(struct vring_desc_state_packed),
1644			GFP_KERNEL);
1645	if (!vq->packed.desc_state)
1646		goto err_desc_state;
1647
1648	memset(vq->packed.desc_state, 0,
1649		num * sizeof(struct vring_desc_state_packed));
1650
1651	/* Put everything in free lists. */
1652	vq->free_head = 0;
1653	for (i = 0; i < num-1; i++)
1654		vq->packed.desc_state[i].next = i + 1;
1655
1656	vq->packed.desc_extra = kmalloc_array(num,
1657			sizeof(struct vring_desc_extra_packed),
1658			GFP_KERNEL);
1659	if (!vq->packed.desc_extra)
1660		goto err_desc_extra;
1661
1662	memset(vq->packed.desc_extra, 0,
1663		num * sizeof(struct vring_desc_extra_packed));
1664
1665	/* No callback?  Tell other side not to bother us. */
1666	if (!callback) {
1667		vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_DISABLE;
1668		vq->packed.vring.driver->flags =
1669			cpu_to_le16(vq->packed.event_flags_shadow);
1670	}
1671
1672	return &vq->vq;
1673
1674err_desc_extra:
1675	kfree(vq->packed.desc_state);
1676err_desc_state:
1677	kfree(vq);
1678err_vq:
1679	vring_free_queue(vdev, event_size_in_bytes, device, ring_dma_addr);
1680err_device:
1681	vring_free_queue(vdev, event_size_in_bytes, driver, ring_dma_addr);
1682err_driver:
1683	vring_free_queue(vdev, ring_size_in_bytes, ring, ring_dma_addr);
1684err_ring:
1685	return NULL;
1686}
1687
1688
1689/*
1690 * Generic functions and exported symbols.
1691 */
1692
1693static inline int virtqueue_add(struct virtqueue *_vq,
1694				struct scatterlist *sgs[],
1695				unsigned int total_sg,
1696				unsigned int out_sgs,
1697				unsigned int in_sgs,
1698				void *data,
1699				void *ctx,
1700				gfp_t gfp)
1701{
1702	struct vring_virtqueue *vq = to_vvq(_vq);
1703
1704	return vq->packed_ring ? virtqueue_add_packed(_vq, sgs, total_sg,
1705					out_sgs, in_sgs, data, ctx, gfp) :
1706				 virtqueue_add_split(_vq, sgs, total_sg,
1707					out_sgs, in_sgs, data, ctx, gfp);
1708}
1709
1710/**
1711 * virtqueue_add_sgs - expose buffers to other end
1712 * @_vq: the struct virtqueue we're talking about.
1713 * @sgs: array of terminated scatterlists.
1714 * @out_sgs: the number of scatterlists readable by other side
1715 * @in_sgs: the number of scatterlists which are writable (after readable ones)
1716 * @data: the token identifying the buffer.
1717 * @gfp: how to do memory allocations (if necessary).
1718 *
1719 * Caller must ensure we don't call this with other virtqueue operations
1720 * at the same time (except where noted).
1721 *
1722 * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
1723 */
1724int virtqueue_add_sgs(struct virtqueue *_vq,
1725		      struct scatterlist *sgs[],
1726		      unsigned int out_sgs,
1727		      unsigned int in_sgs,
1728		      void *data,
1729		      gfp_t gfp)
1730{
1731	unsigned int i, total_sg = 0;
1732
1733	/* Count them first. */
1734	for (i = 0; i < out_sgs + in_sgs; i++) {
1735		struct scatterlist *sg;
1736
1737		for (sg = sgs[i]; sg; sg = sg_next(sg))
1738			total_sg++;
1739	}
1740	return virtqueue_add(_vq, sgs, total_sg, out_sgs, in_sgs,
1741			     data, NULL, gfp);
1742}
1743EXPORT_SYMBOL_GPL(virtqueue_add_sgs);
1744
1745/**
1746 * virtqueue_add_outbuf - expose output buffers to other end
1747 * @vq: the struct virtqueue we're talking about.
1748 * @sg: scatterlist (must be well-formed and terminated!)
1749 * @num: the number of entries in @sg readable by other side
1750 * @data: the token identifying the buffer.
1751 * @gfp: how to do memory allocations (if necessary).
1752 *
1753 * Caller must ensure we don't call this with other virtqueue operations
1754 * at the same time (except where noted).
1755 *
1756 * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
1757 */
1758int virtqueue_add_outbuf(struct virtqueue *vq,
1759			 struct scatterlist *sg, unsigned int num,
1760			 void *data,
1761			 gfp_t gfp)
1762{
1763	return virtqueue_add(vq, &sg, num, 1, 0, data, NULL, gfp);
1764}
1765EXPORT_SYMBOL_GPL(virtqueue_add_outbuf);
1766
1767/**
1768 * virtqueue_add_inbuf - expose input buffers to other end
1769 * @vq: the struct virtqueue we're talking about.
1770 * @sg: scatterlist (must be well-formed and terminated!)
1771 * @num: the number of entries in @sg writable by other side
1772 * @data: the token identifying the buffer.
1773 * @gfp: how to do memory allocations (if necessary).
1774 *
1775 * Caller must ensure we don't call this with other virtqueue operations
1776 * at the same time (except where noted).
1777 *
1778 * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
1779 */
1780int virtqueue_add_inbuf(struct virtqueue *vq,
1781			struct scatterlist *sg, unsigned int num,
1782			void *data,
1783			gfp_t gfp)
1784{
1785	return virtqueue_add(vq, &sg, num, 0, 1, data, NULL, gfp);
1786}
1787EXPORT_SYMBOL_GPL(virtqueue_add_inbuf);
1788
1789/**
1790 * virtqueue_add_inbuf_ctx - expose input buffers to other end
1791 * @vq: the struct virtqueue we're talking about.
1792 * @sg: scatterlist (must be well-formed and terminated!)
1793 * @num: the number of entries in @sg writable by other side
1794 * @data: the token identifying the buffer.
1795 * @ctx: extra context for the token
1796 * @gfp: how to do memory allocations (if necessary).
1797 *
1798 * Caller must ensure we don't call this with other virtqueue operations
1799 * at the same time (except where noted).
1800 *
1801 * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
1802 */
1803int virtqueue_add_inbuf_ctx(struct virtqueue *vq,
1804			struct scatterlist *sg, unsigned int num,
1805			void *data,
1806			void *ctx,
1807			gfp_t gfp)
1808{
1809	return virtqueue_add(vq, &sg, num, 0, 1, data, ctx, gfp);
1810}
1811EXPORT_SYMBOL_GPL(virtqueue_add_inbuf_ctx);
1812
1813/**
1814 * virtqueue_kick_prepare - first half of split virtqueue_kick call.
1815 * @_vq: the struct virtqueue
1816 *
1817 * Instead of virtqueue_kick(), you can do:
1818 *	if (virtqueue_kick_prepare(vq))
1819 *		virtqueue_notify(vq);
1820 *
1821 * This is sometimes useful because the virtqueue_kick_prepare() needs
1822 * to be serialized, but the actual virtqueue_notify() call does not.
1823 */
1824bool virtqueue_kick_prepare(struct virtqueue *_vq)
1825{
1826	struct vring_virtqueue *vq = to_vvq(_vq);
 
 
 
 
 
 
 
1827
1828	return vq->packed_ring ? virtqueue_kick_prepare_packed(_vq) :
1829				 virtqueue_kick_prepare_split(_vq);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1830}
1831EXPORT_SYMBOL_GPL(virtqueue_kick_prepare);
1832
1833/**
1834 * virtqueue_notify - second half of split virtqueue_kick call.
1835 * @_vq: the struct virtqueue
1836 *
1837 * This does not need to be serialized.
1838 *
1839 * Returns false if host notify failed or queue is broken, otherwise true.
1840 */
1841bool virtqueue_notify(struct virtqueue *_vq)
1842{
1843	struct vring_virtqueue *vq = to_vvq(_vq);
1844
1845	if (unlikely(vq->broken))
1846		return false;
1847
1848	/* Prod other side to tell it about changes. */
1849	if (!vq->notify(_vq)) {
1850		vq->broken = true;
1851		return false;
1852	}
1853	return true;
1854}
1855EXPORT_SYMBOL_GPL(virtqueue_notify);
1856
1857/**
1858 * virtqueue_kick - update after add_buf
1859 * @vq: the struct virtqueue
1860 *
1861 * After one or more virtqueue_add_* calls, invoke this to kick
1862 * the other side.
1863 *
1864 * Caller must ensure we don't call this with other virtqueue
1865 * operations at the same time (except where noted).
1866 *
1867 * Returns false if kick failed, otherwise true.
1868 */
1869bool virtqueue_kick(struct virtqueue *vq)
1870{
1871	if (virtqueue_kick_prepare(vq))
1872		return virtqueue_notify(vq);
1873	return true;
1874}
1875EXPORT_SYMBOL_GPL(virtqueue_kick);
1876
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1877/**
1878 * virtqueue_get_buf - get the next used buffer
1879 * @_vq: the struct virtqueue we're talking about.
1880 * @len: the length written into the buffer
1881 * @ctx: extra context for the token
1882 *
1883 * If the device wrote data into the buffer, @len will be set to the
1884 * amount written.  This means you don't need to clear the buffer
1885 * beforehand to ensure there's no data leakage in the case of short
1886 * writes.
1887 *
1888 * Caller must ensure we don't call this with other virtqueue
1889 * operations at the same time (except where noted).
1890 *
1891 * Returns NULL if there are no used buffers, or the "data" token
1892 * handed to virtqueue_add_*().
1893 */
1894void *virtqueue_get_buf_ctx(struct virtqueue *_vq, unsigned int *len,
1895			    void **ctx)
1896{
1897	struct vring_virtqueue *vq = to_vvq(_vq);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1898
1899	return vq->packed_ring ? virtqueue_get_buf_ctx_packed(_vq, len, ctx) :
1900				 virtqueue_get_buf_ctx_split(_vq, len, ctx);
1901}
1902EXPORT_SYMBOL_GPL(virtqueue_get_buf_ctx);
1903
1904void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len)
1905{
1906	return virtqueue_get_buf_ctx(_vq, len, NULL);
1907}
1908EXPORT_SYMBOL_GPL(virtqueue_get_buf);
1909/**
1910 * virtqueue_disable_cb - disable callbacks
1911 * @_vq: the struct virtqueue we're talking about.
1912 *
1913 * Note that this is not necessarily synchronous, hence unreliable and only
1914 * useful as an optimization.
1915 *
1916 * Unlike other operations, this need not be serialized.
1917 */
1918void virtqueue_disable_cb(struct virtqueue *_vq)
1919{
1920	struct vring_virtqueue *vq = to_vvq(_vq);
1921
1922	if (vq->packed_ring)
1923		virtqueue_disable_cb_packed(_vq);
1924	else
1925		virtqueue_disable_cb_split(_vq);
 
 
1926}
1927EXPORT_SYMBOL_GPL(virtqueue_disable_cb);
1928
1929/**
1930 * virtqueue_enable_cb_prepare - restart callbacks after disable_cb
1931 * @_vq: the struct virtqueue we're talking about.
1932 *
1933 * This re-enables callbacks; it returns current queue state
1934 * in an opaque unsigned value. This value should be later tested by
1935 * virtqueue_poll, to detect a possible race between the driver checking for
1936 * more work, and enabling callbacks.
1937 *
1938 * Caller must ensure we don't call this with other virtqueue
1939 * operations at the same time (except where noted).
1940 */
1941unsigned virtqueue_enable_cb_prepare(struct virtqueue *_vq)
1942{
1943	struct vring_virtqueue *vq = to_vvq(_vq);
 
 
 
1944
1945	return vq->packed_ring ? virtqueue_enable_cb_prepare_packed(_vq) :
1946				 virtqueue_enable_cb_prepare_split(_vq);
 
 
 
 
 
 
 
 
 
 
 
1947}
1948EXPORT_SYMBOL_GPL(virtqueue_enable_cb_prepare);
1949
1950/**
1951 * virtqueue_poll - query pending used buffers
1952 * @_vq: the struct virtqueue we're talking about.
1953 * @last_used_idx: virtqueue state (from call to virtqueue_enable_cb_prepare).
1954 *
1955 * Returns "true" if there are pending used buffers in the queue.
1956 *
1957 * This does not need to be serialized.
1958 */
1959bool virtqueue_poll(struct virtqueue *_vq, unsigned last_used_idx)
1960{
1961	struct vring_virtqueue *vq = to_vvq(_vq);
1962
1963	if (unlikely(vq->broken))
1964		return false;
1965
1966	virtio_mb(vq->weak_barriers);
1967	return vq->packed_ring ? virtqueue_poll_packed(_vq, last_used_idx) :
1968				 virtqueue_poll_split(_vq, last_used_idx);
1969}
1970EXPORT_SYMBOL_GPL(virtqueue_poll);
1971
1972/**
1973 * virtqueue_enable_cb - restart callbacks after disable_cb.
1974 * @_vq: the struct virtqueue we're talking about.
1975 *
1976 * This re-enables callbacks; it returns "false" if there are pending
1977 * buffers in the queue, to detect a possible race between the driver
1978 * checking for more work, and enabling callbacks.
1979 *
1980 * Caller must ensure we don't call this with other virtqueue
1981 * operations at the same time (except where noted).
1982 */
1983bool virtqueue_enable_cb(struct virtqueue *_vq)
1984{
1985	unsigned last_used_idx = virtqueue_enable_cb_prepare(_vq);
1986
1987	return !virtqueue_poll(_vq, last_used_idx);
1988}
1989EXPORT_SYMBOL_GPL(virtqueue_enable_cb);
1990
1991/**
1992 * virtqueue_enable_cb_delayed - restart callbacks after disable_cb.
1993 * @_vq: the struct virtqueue we're talking about.
1994 *
1995 * This re-enables callbacks but hints to the other side to delay
1996 * interrupts until most of the available buffers have been processed;
1997 * it returns "false" if there are many pending buffers in the queue,
1998 * to detect a possible race between the driver checking for more work,
1999 * and enabling callbacks.
2000 *
2001 * Caller must ensure we don't call this with other virtqueue
2002 * operations at the same time (except where noted).
2003 */
2004bool virtqueue_enable_cb_delayed(struct virtqueue *_vq)
2005{
2006	struct vring_virtqueue *vq = to_vvq(_vq);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2007
2008	return vq->packed_ring ? virtqueue_enable_cb_delayed_packed(_vq) :
2009				 virtqueue_enable_cb_delayed_split(_vq);
 
 
 
 
 
 
 
 
 
2010}
2011EXPORT_SYMBOL_GPL(virtqueue_enable_cb_delayed);
2012
2013/**
2014 * virtqueue_detach_unused_buf - detach first unused buffer
2015 * @_vq: the struct virtqueue we're talking about.
2016 *
2017 * Returns NULL or the "data" token handed to virtqueue_add_*().
2018 * This is not valid on an active queue; it is useful only for device
2019 * shutdown.
2020 */
2021void *virtqueue_detach_unused_buf(struct virtqueue *_vq)
2022{
2023	struct vring_virtqueue *vq = to_vvq(_vq);
 
 
2024
2025	return vq->packed_ring ? virtqueue_detach_unused_buf_packed(_vq) :
2026				 virtqueue_detach_unused_buf_split(_vq);
2027}
2028EXPORT_SYMBOL_GPL(virtqueue_detach_unused_buf);
2029
2030static inline bool more_used(const struct vring_virtqueue *vq)
2031{
2032	return vq->packed_ring ? more_used_packed(vq) : more_used_split(vq);
 
 
 
 
 
 
 
 
 
 
 
 
 
2033}
 
2034
2035irqreturn_t vring_interrupt(int irq, void *_vq)
2036{
2037	struct vring_virtqueue *vq = to_vvq(_vq);
2038
2039	if (!more_used(vq)) {
2040		pr_debug("virtqueue interrupt with no work for %p\n", vq);
2041		return IRQ_NONE;
2042	}
2043
2044	if (unlikely(vq->broken))
2045		return IRQ_HANDLED;
2046
2047	pr_debug("virtqueue callback for %p (%p)\n", vq, vq->vq.callback);
2048	if (vq->vq.callback)
2049		vq->vq.callback(&vq->vq);
2050
2051	return IRQ_HANDLED;
2052}
2053EXPORT_SYMBOL_GPL(vring_interrupt);
2054
2055/* Only available for split ring */
2056struct virtqueue *__vring_new_virtqueue(unsigned int index,
2057					struct vring vring,
2058					struct virtio_device *vdev,
2059					bool weak_barriers,
2060					bool context,
2061					bool (*notify)(struct virtqueue *),
2062					void (*callback)(struct virtqueue *),
2063					const char *name)
2064{
2065	unsigned int i;
2066	struct vring_virtqueue *vq;
2067
2068	if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED))
2069		return NULL;
2070
2071	vq = kmalloc(sizeof(*vq), GFP_KERNEL);
2072	if (!vq)
2073		return NULL;
2074
2075	vq->packed_ring = false;
2076	vq->vq.callback = callback;
2077	vq->vq.vdev = vdev;
2078	vq->vq.name = name;
2079	vq->vq.num_free = vring.num;
2080	vq->vq.index = index;
2081	vq->we_own_ring = false;
 
 
2082	vq->notify = notify;
2083	vq->weak_barriers = weak_barriers;
2084	vq->broken = false;
2085	vq->last_used_idx = 0;
 
 
2086	vq->num_added = 0;
2087	vq->use_dma_api = vring_use_dma_api(vdev);
2088	list_add_tail(&vq->vq.list, &vdev->vqs);
2089#ifdef DEBUG
2090	vq->in_use = false;
2091	vq->last_add_time_valid = false;
2092#endif
2093
2094	vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) &&
2095		!context;
2096	vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
2097
2098	if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM))
2099		vq->weak_barriers = false;
2100
2101	vq->split.queue_dma_addr = 0;
2102	vq->split.queue_size_in_bytes = 0;
2103
2104	vq->split.vring = vring;
2105	vq->split.avail_flags_shadow = 0;
2106	vq->split.avail_idx_shadow = 0;
2107
2108	/* No callback?  Tell other side not to bother us. */
2109	if (!callback) {
2110		vq->split.avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
2111		if (!vq->event)
2112			vq->split.vring.avail->flags = cpu_to_virtio16(vdev,
2113					vq->split.avail_flags_shadow);
2114	}
2115
2116	vq->split.desc_state = kmalloc_array(vring.num,
2117			sizeof(struct vring_desc_state_split), GFP_KERNEL);
2118	if (!vq->split.desc_state) {
2119		kfree(vq);
2120		return NULL;
2121	}
2122
2123	/* Put everything in free lists. */
2124	vq->free_head = 0;
2125	for (i = 0; i < vring.num-1; i++)
2126		vq->split.vring.desc[i].next = cpu_to_virtio16(vdev, i + 1);
2127	memset(vq->split.desc_state, 0, vring.num *
2128			sizeof(struct vring_desc_state_split));
2129
2130	return &vq->vq;
2131}
2132EXPORT_SYMBOL_GPL(__vring_new_virtqueue);
2133
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2134struct virtqueue *vring_create_virtqueue(
2135	unsigned int index,
2136	unsigned int num,
2137	unsigned int vring_align,
2138	struct virtio_device *vdev,
2139	bool weak_barriers,
2140	bool may_reduce_num,
2141	bool context,
2142	bool (*notify)(struct virtqueue *),
2143	void (*callback)(struct virtqueue *),
2144	const char *name)
2145{
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2146
2147	if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED))
2148		return vring_create_virtqueue_packed(index, num, vring_align,
2149				vdev, weak_barriers, may_reduce_num,
2150				context, notify, callback, name);
2151
2152	return vring_create_virtqueue_split(index, num, vring_align,
2153			vdev, weak_barriers, may_reduce_num,
2154			context, notify, callback, name);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2155}
2156EXPORT_SYMBOL_GPL(vring_create_virtqueue);
2157
2158/* Only available for split ring */
2159struct virtqueue *vring_new_virtqueue(unsigned int index,
2160				      unsigned int num,
2161				      unsigned int vring_align,
2162				      struct virtio_device *vdev,
2163				      bool weak_barriers,
2164				      bool context,
2165				      void *pages,
2166				      bool (*notify)(struct virtqueue *vq),
2167				      void (*callback)(struct virtqueue *vq),
2168				      const char *name)
2169{
2170	struct vring vring;
2171
2172	if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED))
2173		return NULL;
2174
2175	vring_init(&vring, num, pages, vring_align);
2176	return __vring_new_virtqueue(index, vring, vdev, weak_barriers, context,
2177				     notify, callback, name);
2178}
2179EXPORT_SYMBOL_GPL(vring_new_virtqueue);
2180
2181void vring_del_virtqueue(struct virtqueue *_vq)
2182{
2183	struct vring_virtqueue *vq = to_vvq(_vq);
2184
2185	if (vq->we_own_ring) {
2186		if (vq->packed_ring) {
2187			vring_free_queue(vq->vq.vdev,
2188					 vq->packed.ring_size_in_bytes,
2189					 vq->packed.vring.desc,
2190					 vq->packed.ring_dma_addr);
2191
2192			vring_free_queue(vq->vq.vdev,
2193					 vq->packed.event_size_in_bytes,
2194					 vq->packed.vring.driver,
2195					 vq->packed.driver_event_dma_addr);
2196
2197			vring_free_queue(vq->vq.vdev,
2198					 vq->packed.event_size_in_bytes,
2199					 vq->packed.vring.device,
2200					 vq->packed.device_event_dma_addr);
2201
2202			kfree(vq->packed.desc_state);
2203			kfree(vq->packed.desc_extra);
2204		} else {
2205			vring_free_queue(vq->vq.vdev,
2206					 vq->split.queue_size_in_bytes,
2207					 vq->split.vring.desc,
2208					 vq->split.queue_dma_addr);
2209		}
2210	}
2211	if (!vq->packed_ring)
2212		kfree(vq->split.desc_state);
2213	list_del(&_vq->list);
2214	kfree(vq);
2215}
2216EXPORT_SYMBOL_GPL(vring_del_virtqueue);
2217
2218/* Manipulates transport-specific feature bits. */
2219void vring_transport_features(struct virtio_device *vdev)
2220{
2221	unsigned int i;
2222
2223	for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++) {
2224		switch (i) {
2225		case VIRTIO_RING_F_INDIRECT_DESC:
2226			break;
2227		case VIRTIO_RING_F_EVENT_IDX:
2228			break;
2229		case VIRTIO_F_VERSION_1:
2230			break;
2231		case VIRTIO_F_ACCESS_PLATFORM:
2232			break;
2233		case VIRTIO_F_RING_PACKED:
2234			break;
2235		case VIRTIO_F_ORDER_PLATFORM:
2236			break;
2237		default:
2238			/* We don't understand this bit. */
2239			__virtio_clear_bit(vdev, i);
2240		}
2241	}
2242}
2243EXPORT_SYMBOL_GPL(vring_transport_features);
2244
2245/**
2246 * virtqueue_get_vring_size - return the size of the virtqueue's vring
2247 * @_vq: the struct virtqueue containing the vring of interest.
2248 *
2249 * Returns the size of the vring.  This is mainly used for boasting to
2250 * userspace.  Unlike other operations, this need not be serialized.
2251 */
2252unsigned int virtqueue_get_vring_size(struct virtqueue *_vq)
2253{
2254
2255	struct vring_virtqueue *vq = to_vvq(_vq);
2256
2257	return vq->packed_ring ? vq->packed.vring.num : vq->split.vring.num;
2258}
2259EXPORT_SYMBOL_GPL(virtqueue_get_vring_size);
2260
2261bool virtqueue_is_broken(struct virtqueue *_vq)
2262{
2263	struct vring_virtqueue *vq = to_vvq(_vq);
2264
2265	return vq->broken;
2266}
2267EXPORT_SYMBOL_GPL(virtqueue_is_broken);
2268
2269/*
2270 * This should prevent the device from being used, allowing drivers to
2271 * recover.  You may need to grab appropriate locks to flush.
2272 */
2273void virtio_break_device(struct virtio_device *dev)
2274{
2275	struct virtqueue *_vq;
2276
2277	list_for_each_entry(_vq, &dev->vqs, list) {
2278		struct vring_virtqueue *vq = to_vvq(_vq);
2279		vq->broken = true;
2280	}
2281}
2282EXPORT_SYMBOL_GPL(virtio_break_device);
2283
2284dma_addr_t virtqueue_get_desc_addr(struct virtqueue *_vq)
2285{
2286	struct vring_virtqueue *vq = to_vvq(_vq);
2287
2288	BUG_ON(!vq->we_own_ring);
2289
2290	if (vq->packed_ring)
2291		return vq->packed.ring_dma_addr;
2292
2293	return vq->split.queue_dma_addr;
2294}
2295EXPORT_SYMBOL_GPL(virtqueue_get_desc_addr);
2296
2297dma_addr_t virtqueue_get_avail_addr(struct virtqueue *_vq)
2298{
2299	struct vring_virtqueue *vq = to_vvq(_vq);
2300
2301	BUG_ON(!vq->we_own_ring);
2302
2303	if (vq->packed_ring)
2304		return vq->packed.driver_event_dma_addr;
2305
2306	return vq->split.queue_dma_addr +
2307		((char *)vq->split.vring.avail - (char *)vq->split.vring.desc);
2308}
2309EXPORT_SYMBOL_GPL(virtqueue_get_avail_addr);
2310
2311dma_addr_t virtqueue_get_used_addr(struct virtqueue *_vq)
2312{
2313	struct vring_virtqueue *vq = to_vvq(_vq);
2314
2315	BUG_ON(!vq->we_own_ring);
2316
2317	if (vq->packed_ring)
2318		return vq->packed.device_event_dma_addr;
2319
2320	return vq->split.queue_dma_addr +
2321		((char *)vq->split.vring.used - (char *)vq->split.vring.desc);
2322}
2323EXPORT_SYMBOL_GPL(virtqueue_get_used_addr);
2324
2325/* Only available for split ring */
2326const struct vring *virtqueue_get_vring(struct virtqueue *vq)
2327{
2328	return &to_vvq(vq)->split.vring;
2329}
2330EXPORT_SYMBOL_GPL(virtqueue_get_vring);
2331
2332MODULE_LICENSE("GPL");