Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

Pull virtio/vhost updates from Michael Tsirkin:
 "New features, performance improvements, cleanups:

   - basic polling support for vhost
   - rework virtio to optionally use DMA API, fixing it on Xen
   - balloon stats gained a new entry
   - using the new napi_alloc_skb speeds up virtio net
   - virtio blk stats can now be read while another VCPU is busy
     inflating or deflating the balloon

  plus misc cleanups in various places"

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  virtio_net: replace netdev_alloc_skb_ip_align() with napi_alloc_skb()
  vhost_net: basic polling support
  vhost: introduce vhost_vq_avail_empty()
  vhost: introduce vhost_has_work()
  virtio_balloon: Allow to resize and update the balloon stats in parallel
  virtio_balloon: Use a workqueue instead of "vballoon" kthread
  virtio/s390: size of SET_IND payload
  virtio/s390: use dev_to_virtio
  vhost: rename vhost_init_used()
  vhost: rename cross-endian helpers
  virtio_blk: VIRTIO_BLK_F_WCE->VIRTIO_BLK_F_FLUSH
  vring: Use the DMA API on Xen
  virtio_pci: Use the DMA API if enabled
  virtio_mmio: Use the DMA API if enabled
  virtio: Add improved queue allocation API
  virtio_ring: Support DMA APIs
  vring: Introduce vring_use_dma_api()
  s390/dma: Allow per device dma ops
  alpha/dma: use common noop dma ops
  dma: Provide simple noop dma ops

1 files changed, 377 insertions, 62 deletions

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index e12e385f7ac3..5c802d47892c 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -24,6 +24,8 @@
 #include <linux/module.h>
 #include <linux/hrtimer.h>
 #include <linux/kmemleak.h>
+#include <linux/dma-mapping.h>
+#include <xen/xen.h>
 
 #ifdef DEBUG
 /* For development, we want to crash whenever the ring is screwed. */
@@ -54,6 +56,11 @@
 #define END_USE(vq)
 #endif
 
+struct vring_desc_state {
+	void *data;			/* Data for callback. */
+	struct vring_desc *indir_desc;	/* Indirect descriptor, if any. */
+};
+
 struct vring_virtqueue {
 	struct virtqueue vq;
 
@@ -89,6 +96,11 @@ struct vring_virtqueue {
 	/* How to notify other side. FIXME: commonalize hcalls! */
 	bool (*notify)(struct virtqueue *vq);
 
+	/* DMA, allocation, and size information */
+	bool we_own_ring;
+	size_t queue_size_in_bytes;
+	dma_addr_t queue_dma_addr;
+
 #ifdef DEBUG
 	/* They're supposed to lock for us. */
 	unsigned int in_use;
@@ -98,12 +110,120 @@ struct vring_virtqueue {
 	ktime_t last_add_time;
 #endif
 
-	/* Tokens for callbacks. */
-	void *data[];
+	/* Per-descriptor state. */
+	struct vring_desc_state desc_state[];
 };
 
 #define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)
 
+/*
+ * The interaction between virtio and a possible IOMMU is a mess.
+ *
+ * On most systems with virtio, physical addresses match bus addresses,
+ * and it doesn't particularly matter whether we use the DMA API.
+ *
+ * On some systems, including Xen and any system with a physical device
+ * that speaks virtio behind a physical IOMMU, we must use the DMA API
+ * for virtio DMA to work at all.
+ *
+ * On other systems, including SPARC and PPC64, virtio-pci devices are
+ * enumerated as though they are behind an IOMMU, but the virtio host
+ * ignores the IOMMU, so we must either pretend that the IOMMU isn't
+ * there or somehow map everything as the identity.
+ *
+ * For the time being, we preserve historic behavior and bypass the DMA
+ * API.
+ */
+
+static bool vring_use_dma_api(struct virtio_device *vdev)
+{
+	/*
+	 * In theory, it's possible to have a buggy QEMU-supposed
+	 * emulated Q35 IOMMU and Xen enabled at the same time.  On
+	 * such a configuration, virtio has never worked and will
+	 * not work without an even larger kludge.  Instead, enable
+	 * the DMA API if we're a Xen guest, which at least allows
+	 * all of the sensible Xen configurations to work correctly.
+	 */
+	if (xen_domain())
+		return true;
+
+	return false;
+}
+
+/*
+ * The DMA ops on various arches are rather gnarly right now, and
+ * making all of the arch DMA ops work on the vring device itself
+ * is a mess.  For now, we use the parent device for DMA ops.
+ */
+struct device *vring_dma_dev(const struct vring_virtqueue *vq)
+{
+	return vq->vq.vdev->dev.parent;
+}
+
+/* Map one sg entry. */
+static dma_addr_t vring_map_one_sg(const struct vring_virtqueue *vq,
+				   struct scatterlist *sg,
+				   enum dma_data_direction direction)
+{
+	if (!vring_use_dma_api(vq->vq.vdev))
+		return (dma_addr_t)sg_phys(sg);
+
+	/*
+	 * We can't use dma_map_sg, because we don't use scatterlists in
+	 * the way it expects (we don't guarantee that the scatterlist
+	 * will exist for the lifetime of the mapping).
+	 */
+	return dma_map_page(vring_dma_dev(vq),
+			    sg_page(sg), sg->offset, sg->length,
+			    direction);
+}
+
+static dma_addr_t vring_map_single(const struct vring_virtqueue *vq,
+				   void *cpu_addr, size_t size,
+				   enum dma_data_direction direction)
+{
+	if (!vring_use_dma_api(vq->vq.vdev))
+		return (dma_addr_t)virt_to_phys(cpu_addr);
+
+	return dma_map_single(vring_dma_dev(vq),
+			      cpu_addr, size, direction);
+}
+
+static void vring_unmap_one(const struct vring_virtqueue *vq,
+			    struct vring_desc *desc)
+{
+	u16 flags;
+
+	if (!vring_use_dma_api(vq->vq.vdev))
+		return;
+
+	flags = virtio16_to_cpu(vq->vq.vdev, desc->flags);
+
+	if (flags & VRING_DESC_F_INDIRECT) {
+		dma_unmap_single(vring_dma_dev(vq),
+				 virtio64_to_cpu(vq->vq.vdev, desc->addr),
+				 virtio32_to_cpu(vq->vq.vdev, desc->len),
+				 (flags & VRING_DESC_F_WRITE) ?
+				 DMA_FROM_DEVICE : DMA_TO_DEVICE);
+	} else {
+		dma_unmap_page(vring_dma_dev(vq),
+			       virtio64_to_cpu(vq->vq.vdev, desc->addr),
+			       virtio32_to_cpu(vq->vq.vdev, desc->len),
+			       (flags & VRING_DESC_F_WRITE) ?
+			       DMA_FROM_DEVICE : DMA_TO_DEVICE);
+	}
+}
+
+static int vring_mapping_error(const struct vring_virtqueue *vq,
+			       dma_addr_t addr)
+{
+	if (!vring_use_dma_api(vq->vq.vdev))
+		return 0;
+
+	return dma_mapping_error(vring_dma_dev(vq), addr);
+}
+
 static struct vring_desc *alloc_indirect(struct virtqueue *_vq,
 					 unsigned int total_sg, gfp_t gfp)
 {
@@ -137,7 +257,7 @@ static inline int virtqueue_add(struct virtqueue *_vq,
 	struct vring_virtqueue *vq = to_vvq(_vq);
 	struct scatterlist *sg;
 	struct vring_desc *desc;
-	unsigned int i, n, avail, descs_used, uninitialized_var(prev);
+	unsigned int i, n, avail, descs_used, uninitialized_var(prev), err_idx;
 	int head;
 	bool indirect;
 
@@ -177,21 +297,15 @@ static inline int virtqueue_add(struct virtqueue *_vq,
 
 	if (desc) {
 		/* Use a single buffer which doesn't continue */
-		vq->vring.desc[head].flags = cpu_to_virtio16(_vq->vdev, VRING_DESC_F_INDIRECT);
-		vq->vring.desc[head].addr = cpu_to_virtio64(_vq->vdev, virt_to_phys(desc));
-		/* avoid kmemleak false positive (hidden by virt_to_phys) */
-		kmemleak_ignore(desc);
-		vq->vring.desc[head].len = cpu_to_virtio32(_vq->vdev, total_sg * sizeof(struct vring_desc));
-
+		indirect = true;
 		/* Set up rest to use this indirect table. */
 		i = 0;
 		descs_used = 1;
-		indirect = true;
 	} else {
+		indirect = false;
 		desc = vq->vring.desc;
 		i = head;
 		descs_used = total_sg;
-		indirect = false;
 	}
 
 	if (vq->vq.num_free < descs_used) {
@@ -206,13 +320,14 @@ static inline int virtqueue_add(struct virtqueue *_vq,
 		return -ENOSPC;
 	}
 
-	/* We're about to use some buffers from the free list. */
-	vq->vq.num_free -= descs_used;
-
 	for (n = 0; n < out_sgs; n++) {
 		for (sg = sgs[n]; sg; sg = sg_next(sg)) {
+			dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_TO_DEVICE);
+			if (vring_mapping_error(vq, addr))
+				goto unmap_release;
+
 			desc[i].flags = cpu_to_virtio16(_vq->vdev, VRING_DESC_F_NEXT);
-			desc[i].addr = cpu_to_virtio64(_vq->vdev, sg_phys(sg));
+			desc[i].addr = cpu_to_virtio64(_vq->vdev, addr);
 			desc[i].len = cpu_to_virtio32(_vq->vdev, sg->length);
 			prev = i;
 			i = virtio16_to_cpu(_vq->vdev, desc[i].next);
@@ -220,8 +335,12 @@ static inline int virtqueue_add(struct virtqueue *_vq,
 	}
 	for (; n < (out_sgs + in_sgs); n++) {
 		for (sg = sgs[n]; sg; sg = sg_next(sg)) {
+			dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_FROM_DEVICE);
+			if (vring_mapping_error(vq, addr))
+				goto unmap_release;
+
 			desc[i].flags = cpu_to_virtio16(_vq->vdev, VRING_DESC_F_NEXT | VRING_DESC_F_WRITE);
-			desc[i].addr = cpu_to_virtio64(_vq->vdev, sg_phys(sg));
+			desc[i].addr = cpu_to_virtio64(_vq->vdev, addr);
 			desc[i].len = cpu_to_virtio32(_vq->vdev, sg->length);
 			prev = i;
 			i = virtio16_to_cpu(_vq->vdev, desc[i].next);
@@ -230,14 +349,33 @@ static inline int virtqueue_add(struct virtqueue *_vq,
 	/* Last one doesn't continue. */
 	desc[prev].flags &= cpu_to_virtio16(_vq->vdev, ~VRING_DESC_F_NEXT);
 
+	if (indirect) {
+		/* Now that the indirect table is filled in, map it. */
+		dma_addr_t addr = vring_map_single(
+			vq, desc, total_sg * sizeof(struct vring_desc),
+			DMA_TO_DEVICE);
+		if (vring_mapping_error(vq, addr))
+			goto unmap_release;
+
+		vq->vring.desc[head].flags = cpu_to_virtio16(_vq->vdev, VRING_DESC_F_INDIRECT);
+		vq->vring.desc[head].addr = cpu_to_virtio64(_vq->vdev, addr);
+
+		vq->vring.desc[head].len = cpu_to_virtio32(_vq->vdev, total_sg * sizeof(struct vring_desc));
+	}
+
+	/* We're using some buffers from the free list. */
+	vq->vq.num_free -= descs_used;
+
 	/* Update free pointer */
 	if (indirect)
 		vq->free_head = virtio16_to_cpu(_vq->vdev, vq->vring.desc[head].next);
 	else
 		vq->free_head = i;
 
-	/* Set token. */
-	vq->data[head] = data;
+	/* Store token and indirect buffer state. */
+	vq->desc_state[head].data = data;
+	if (indirect)
+		vq->desc_state[head].indir_desc = desc;
 
 	/* Put entry in available array (but don't update avail->idx until they
 	 * do sync). */
@@ -260,6 +398,24 @@ static inline int virtqueue_add(struct virtqueue *_vq,
 		virtqueue_kick(_vq);
 
 	return 0;
+
+unmap_release:
+	err_idx = i;
+	i = head;
+
+	for (n = 0; n < total_sg; n++) {
+		if (i == err_idx)
+			break;
+		vring_unmap_one(vq, &desc[i]);
+		i = vq->vring.desc[i].next;
+	}
+
+	vq->vq.num_free += total_sg;
+
+	if (indirect)
+		kfree(desc);
+
+	return -EIO;
 }
 
 /**
@@ -430,27 +586,43 @@ EXPORT_SYMBOL_GPL(virtqueue_kick);
 
 static void detach_buf(struct vring_virtqueue *vq, unsigned int head)
 {
-	unsigned int i;
+	unsigned int i, j;
+	u16 nextflag = cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_NEXT);
 
 	/* Clear data ptr. */
-	vq->data[head] = NULL;
+	vq->desc_state[head].data = NULL;
 
-	/* Put back on free list: find end */
+	/* Put back on free list: unmap first-level descriptors and find end */
 	i = head;
 
-	/* Free the indirect table */
-	if (vq->vring.desc[i].flags & cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_INDIRECT))
-		kfree(phys_to_virt(virtio64_to_cpu(vq->vq.vdev, vq->vring.desc[i].addr)));
-
-	while (vq->vring.desc[i].flags & cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_NEXT)) {
+	while (vq->vring.desc[i].flags & nextflag) {
+		vring_unmap_one(vq, &vq->vring.desc[i]);
 		i = virtio16_to_cpu(vq->vq.vdev, vq->vring.desc[i].next);
 		vq->vq.num_free++;
 	}
 
+	vring_unmap_one(vq, &vq->vring.desc[i]);
 	vq->vring.desc[i].next = cpu_to_virtio16(vq->vq.vdev, vq->free_head);
 	vq->free_head = head;
+
 	/* Plus final descriptor */
 	vq->vq.num_free++;
+
+	/* Free the indirect table, if any, now that it's unmapped. */
+	if (vq->desc_state[head].indir_desc) {
+		struct vring_desc *indir_desc = vq->desc_state[head].indir_desc;
+		u32 len = virtio32_to_cpu(vq->vq.vdev, vq->vring.desc[head].len);
+
+		BUG_ON(!(vq->vring.desc[head].flags &
+			 cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_INDIRECT)));
+		BUG_ON(len == 0 || len % sizeof(struct vring_desc));
+
+		for (j = 0; j < len / sizeof(struct vring_desc); j++)
+			vring_unmap_one(vq, &indir_desc[j]);
+
+		kfree(vq->desc_state[head].indir_desc);
+		vq->desc_state[head].indir_desc = NULL;
+	}
 }
 
 static inline bool more_used(const struct vring_virtqueue *vq)
@@ -505,13 +677,13 @@ void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len)
 		BAD_RING(vq, "id %u out of range\n", i);
 		return NULL;
 	}
-	if (unlikely(!vq->data[i])) {
+	if (unlikely(!vq->desc_state[i].data)) {
 		BAD_RING(vq, "id %u is not a head!\n", i);
 		return NULL;
 	}
 
 	/* detach_buf clears data, so grab it now. */
-	ret = vq->data[i];
+	ret = vq->desc_state[i].data;
 	detach_buf(vq, i);
 	vq->last_used_idx++;
 	/* If we expect an interrupt for the next entry, tell host
@@ -685,10 +857,10 @@ void *virtqueue_detach_unused_buf(struct virtqueue *_vq)
 	START_USE(vq);
 
 	for (i = 0; i < vq->vring.num; i++) {
-		if (!vq->data[i])
+		if (!vq->desc_state[i].data)
 			continue;
 		/* detach_buf clears data, so grab it now. */
-		buf = vq->data[i];
+		buf = vq->desc_state[i].data;
 		detach_buf(vq, i);
 		vq->avail_idx_shadow--;
 		vq->vring.avail->idx = cpu_to_virtio16(_vq->vdev, vq->avail_idx_shadow);
@@ -723,35 +895,31 @@ irqreturn_t vring_interrupt(int irq, void *_vq)
 }
 EXPORT_SYMBOL_GPL(vring_interrupt);
 
-struct virtqueue *vring_new_virtqueue(unsigned int index,
-				      unsigned int num,
-				      unsigned int vring_align,
-				      struct virtio_device *vdev,
-				      bool weak_barriers,
-				      void *pages,
-				      bool (*notify)(struct virtqueue *),
-				      void (*callback)(struct virtqueue *),
-				      const char *name)
+struct virtqueue *__vring_new_virtqueue(unsigned int index,
+					struct vring vring,
+					struct virtio_device *vdev,
+					bool weak_barriers,
+					bool (*notify)(struct virtqueue *),
+					void (*callback)(struct virtqueue *),
+					const char *name)
 {
-	struct vring_virtqueue *vq;
 	unsigned int i;
+	struct vring_virtqueue *vq;
 
-	/* We assume num is a power of 2. */
-	if (num & (num - 1)) {
-		dev_warn(&vdev->dev, "Bad virtqueue length %u\n", num);
-		return NULL;
-	}
-
-	vq = kmalloc(sizeof(*vq) + sizeof(void *)*num, GFP_KERNEL);
+	vq = kmalloc(sizeof(*vq) + vring.num * sizeof(struct vring_desc_state),
+		     GFP_KERNEL);
 	if (!vq)
 		return NULL;
 
-	vring_init(&vq->vring, num, pages, vring_align);
+	vq->vring = vring;
 	vq->vq.callback = callback;
 	vq->vq.vdev = vdev;
 	vq->vq.name = name;
-	vq->vq.num_free = num;
+	vq->vq.num_free = vring.num;
 	vq->vq.index = index;
+	vq->we_own_ring = false;
+	vq->queue_dma_addr = 0;
+	vq->queue_size_in_bytes = 0;
 	vq->notify = notify;
 	vq->weak_barriers = weak_barriers;
 	vq->broken = false;
@@ -776,20 +944,145 @@ struct virtqueue *vring_new_virtqueue(unsigned int index,
 
 	/* Put everything in free lists. */
 	vq->free_head = 0;
-	for (i = 0; i < num-1; i++) {
+	for (i = 0; i < vring.num-1; i++)
 		vq->vring.desc[i].next = cpu_to_virtio16(vdev, i + 1);
-		vq->data[i] = NULL;
-	}
-	vq->data[i] = NULL;
+	memset(vq->desc_state, 0, vring.num * sizeof(struct vring_desc_state));
 
 	return &vq->vq;
 }
+EXPORT_SYMBOL_GPL(__vring_new_virtqueue);
+
+static void *vring_alloc_queue(struct virtio_device *vdev, size_t size,
+			      dma_addr_t *dma_handle, gfp_t flag)
+{
+	if (vring_use_dma_api(vdev)) {
+		return dma_alloc_coherent(vdev->dev.parent, size,
+					  dma_handle, flag);
+	} else {
+		void *queue = alloc_pages_exact(PAGE_ALIGN(size), flag);
+		if (queue) {
+			phys_addr_t phys_addr = virt_to_phys(queue);
+			*dma_handle = (dma_addr_t)phys_addr;
+
+			/*
+			 * Sanity check: make sure we dind't truncate
+			 * the address.  The only arches I can find that
+			 * have 64-bit phys_addr_t but 32-bit dma_addr_t
+			 * are certain non-highmem MIPS and x86
+			 * configurations, but these configurations
+			 * should never allocate physical pages above 32
+			 * bits, so this is fine.  Just in case, throw a
+			 * warning and abort if we end up with an
+			 * unrepresentable address.
+			 */
+			if (WARN_ON_ONCE(*dma_handle != phys_addr)) {
+				free_pages_exact(queue, PAGE_ALIGN(size));
+				return NULL;
+			}
+		}
+		return queue;
+	}
+}
+
+static void vring_free_queue(struct virtio_device *vdev, size_t size,
+			     void *queue, dma_addr_t dma_handle)
+{
+	if (vring_use_dma_api(vdev)) {
+		dma_free_coherent(vdev->dev.parent, size, queue, dma_handle);
+	} else {
+		free_pages_exact(queue, PAGE_ALIGN(size));
+	}
+}
+
+struct virtqueue *vring_create_virtqueue(
+	unsigned int index,
+	unsigned int num,
+	unsigned int vring_align,
+	struct virtio_device *vdev,
+	bool weak_barriers,
+	bool may_reduce_num,
+	bool (*notify)(struct virtqueue *),
+	void (*callback)(struct virtqueue *),
+	const char *name)
+{
+	struct virtqueue *vq;
+	void *queue;
+	dma_addr_t dma_addr;
+	size_t queue_size_in_bytes;
+	struct vring vring;
+
+	/* We assume num is a power of 2. */
+	if (num & (num - 1)) {
+		dev_warn(&vdev->dev, "Bad virtqueue length %u\n", num);
+		return NULL;
+	}
+
+	/* TODO: allocate each queue chunk individually */
+	for (; num && vring_size(num, vring_align) > PAGE_SIZE; num /= 2) {
+		queue = vring_alloc_queue(vdev, vring_size(num, vring_align),
+					  &dma_addr,
+					  GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
+		if (queue)
+			break;
+	}
+
+	if (!num)
+		return NULL;
+
+	if (!queue) {
+		/* Try to get a single page. You are my only hope! */
+		queue = vring_alloc_queue(vdev, vring_size(num, vring_align),
+					  &dma_addr, GFP_KERNEL|__GFP_ZERO);
+	}
+	if (!queue)
+		return NULL;
+
+	queue_size_in_bytes = vring_size(num, vring_align);
+	vring_init(&vring, num, queue, vring_align);
+
+	vq = __vring_new_virtqueue(index, vring, vdev, weak_barriers,
+				   notify, callback, name);
+	if (!vq) {
+		vring_free_queue(vdev, queue_size_in_bytes, queue,
+				 dma_addr);
+		return NULL;
+	}
+
+	to_vvq(vq)->queue_dma_addr = dma_addr;
+	to_vvq(vq)->queue_size_in_bytes = queue_size_in_bytes;
+	to_vvq(vq)->we_own_ring = true;
+
+	return vq;
+}
+EXPORT_SYMBOL_GPL(vring_create_virtqueue);
+
+struct virtqueue *vring_new_virtqueue(unsigned int index,
+				      unsigned int num,
+				      unsigned int vring_align,
+				      struct virtio_device *vdev,
+				      bool weak_barriers,
+				      void *pages,
+				      bool (*notify)(struct virtqueue *vq),
+				      void (*callback)(struct virtqueue *vq),
+				      const char *name)
+{
+	struct vring vring;
+	vring_init(&vring, num, pages, vring_align);
+	return __vring_new_virtqueue(index, vring, vdev, weak_barriers,
+				     notify, callback, name);
+}
 EXPORT_SYMBOL_GPL(vring_new_virtqueue);
 
-void vring_del_virtqueue(struct virtqueue *vq)
+void vring_del_virtqueue(struct virtqueue *_vq)
 {
-	list_del(&vq->list);
-	kfree(to_vvq(vq));
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	if (vq->we_own_ring) {
+		vring_free_queue(vq->vq.vdev, vq->queue_size_in_bytes,
+				 vq->vring.desc, vq->queue_dma_addr);
+	}
+	list_del(&_vq->list);
+	kfree(vq);
 }
 EXPORT_SYMBOL_GPL(vring_del_virtqueue);
 
@@ -853,20 +1146,42 @@ void virtio_break_device(struct virtio_device *dev)
 }
 EXPORT_SYMBOL_GPL(virtio_break_device);
 
-void *virtqueue_get_avail(struct virtqueue *_vq)
+dma_addr_t virtqueue_get_desc_addr(struct virtqueue *_vq)
 {
 	struct vring_virtqueue *vq = to_vvq(_vq);
 
-	return vq->vring.avail;
+	BUG_ON(!vq->we_own_ring);
+
+	return vq->queue_dma_addr;
 }
-EXPORT_SYMBOL_GPL(virtqueue_get_avail);
+EXPORT_SYMBOL_GPL(virtqueue_get_desc_addr);
 
-void *virtqueue_get_used(struct virtqueue *_vq)
+dma_addr_t virtqueue_get_avail_addr(struct virtqueue *_vq)
 {
 	struct vring_virtqueue *vq = to_vvq(_vq);
 
-	return vq->vring.used;
+	BUG_ON(!vq->we_own_ring);
+
+	return vq->queue_dma_addr +
+		((char *)vq->vring.avail - (char *)vq->vring.desc);
+}
+EXPORT_SYMBOL_GPL(virtqueue_get_avail_addr);
+
+dma_addr_t virtqueue_get_used_addr(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	BUG_ON(!vq->we_own_ring);
+
+	return vq->queue_dma_addr +
+		((char *)vq->vring.used - (char *)vq->vring.desc);
+}
+EXPORT_SYMBOL_GPL(virtqueue_get_used_addr);
+
+const struct vring *virtqueue_get_vring(struct virtqueue *vq)
+{
+	return &to_vvq(vq)->vring;
 }
-EXPORT_SYMBOL_GPL(virtqueue_get_used);
+EXPORT_SYMBOL_GPL(virtqueue_get_vring);
 
 MODULE_LICENSE("GPL");