]> git.baikalelectronics.ru Git - kernel.git/commitdiff
virtio_ring: introduce packed ring support
authorTiwei Bie <tiwei.bie@intel.com>
Wed, 21 Nov 2018 10:03:27 +0000 (18:03 +0800)
committerDavid S. Miller <davem@davemloft.net>
Tue, 27 Nov 2018 06:17:39 +0000 (22:17 -0800)
Introduce the packed ring support. Packed ring can only be
created by vring_create_virtqueue() and each chunk of packed
ring will be allocated individually. Packed ring can not be
created on preallocated memory by vring_new_virtqueue() or
the likes currently.

Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
drivers/virtio/virtio_ring.c

index aafe1969b45e3d5fe943caf0ba1a05ba18db1558..b63eee2034e78fb518852a3fa7abc1b46db305a5 100644 (file)
@@ -83,9 +83,26 @@ struct vring_desc_state_split {
        struct vring_desc *indir_desc;  /* Indirect descriptor, if any. */
 };
 
+struct vring_desc_state_packed {
+       void *data;                     /* Data for callback. */
+       struct vring_packed_desc *indir_desc; /* Indirect descriptor, if any. */
+       u16 num;                        /* Descriptor list length. */
+       u16 next;                       /* The next desc state in a list. */
+       u16 last;                       /* The last desc state in a list. */
+};
+
+struct vring_desc_extra_packed {
+       dma_addr_t addr;                /* Buffer DMA addr. */
+       u32 len;                        /* Buffer length. */
+       u16 flags;                      /* Descriptor flags. */
+};
+
 struct vring_virtqueue {
        struct virtqueue vq;
 
+       /* Is this a packed ring? */
+       bool packed_ring;
+
        /* Is DMA API used? */
        bool use_dma_api;
 
@@ -109,23 +126,64 @@ struct vring_virtqueue {
        /* Last used index we've seen. */
        u16 last_used_idx;
 
-       struct {
-               /* Actual memory layout for this queue */
-               struct vring vring;
+       union {
+               /* Available for split ring */
+               struct {
+                       /* Actual memory layout for this queue. */
+                       struct vring vring;
+
+                       /* Last written value to avail->flags */
+                       u16 avail_flags_shadow;
 
-               /* Last written value to avail->flags */
-               u16 avail_flags_shadow;
+                       /*
+                        * Last written value to avail->idx in
+                        * guest byte order.
+                        */
+                       u16 avail_idx_shadow;
+
+                       /* Per-descriptor state. */
+                       struct vring_desc_state_split *desc_state;
+
+                       /* DMA address and size information */
+                       dma_addr_t queue_dma_addr;
+                       size_t queue_size_in_bytes;
+               } split;
 
-               /* Last written value to avail->idx in guest byte order */
-               u16 avail_idx_shadow;
+               /* Available for packed ring */
+               struct {
+                       /* Actual memory layout for this queue. */
+                       struct vring_packed vring;
 
-               /* Per-descriptor state. */
-               struct vring_desc_state_split *desc_state;
+                       /* Driver ring wrap counter. */
+                       bool avail_wrap_counter;
 
-               /* DMA, allocation, and size information */
-               size_t queue_size_in_bytes;
-               dma_addr_t queue_dma_addr;
-       } split;
+                       /* Device ring wrap counter. */
+                       bool used_wrap_counter;
+
+                       /* Avail used flags. */
+                       u16 avail_used_flags;
+
+                       /* Index of the next avail descriptor. */
+                       u16 next_avail_idx;
+
+                       /*
+                        * Last written value to driver->flags in
+                        * guest byte order.
+                        */
+                       u16 event_flags_shadow;
+
+                       /* Per-descriptor state. */
+                       struct vring_desc_state_packed *desc_state;
+                       struct vring_desc_extra_packed *desc_extra;
+
+                       /* DMA address and size information */
+                       dma_addr_t ring_dma_addr;
+                       dma_addr_t driver_event_dma_addr;
+                       dma_addr_t device_event_dma_addr;
+                       size_t ring_size_in_bytes;
+                       size_t event_size_in_bytes;
+               } packed;
+       };
 
        /* How to notify other side. FIXME: commonalize hcalls! */
        bool (*notify)(struct virtqueue *vq);
@@ -840,6 +898,717 @@ static struct virtqueue *vring_create_virtqueue_split(
 }
 
 
+/*
+ * Packed ring specific functions - *_packed().
+ */
+
+static void vring_unmap_state_packed(const struct vring_virtqueue *vq,
+                                    struct vring_desc_extra_packed *state)
+{
+       u16 flags;
+
+       if (!vq->use_dma_api)
+               return;
+
+       flags = state->flags;
+
+       if (flags & VRING_DESC_F_INDIRECT) {
+               dma_unmap_single(vring_dma_dev(vq),
+                                state->addr, state->len,
+                                (flags & VRING_DESC_F_WRITE) ?
+                                DMA_FROM_DEVICE : DMA_TO_DEVICE);
+       } else {
+               dma_unmap_page(vring_dma_dev(vq),
+                              state->addr, state->len,
+                              (flags & VRING_DESC_F_WRITE) ?
+                              DMA_FROM_DEVICE : DMA_TO_DEVICE);
+       }
+}
+
+static void vring_unmap_desc_packed(const struct vring_virtqueue *vq,
+                                  struct vring_packed_desc *desc)
+{
+       u16 flags;
+
+       if (!vq->use_dma_api)
+               return;
+
+       flags = le16_to_cpu(desc->flags);
+
+       if (flags & VRING_DESC_F_INDIRECT) {
+               dma_unmap_single(vring_dma_dev(vq),
+                                le64_to_cpu(desc->addr),
+                                le32_to_cpu(desc->len),
+                                (flags & VRING_DESC_F_WRITE) ?
+                                DMA_FROM_DEVICE : DMA_TO_DEVICE);
+       } else {
+               dma_unmap_page(vring_dma_dev(vq),
+                              le64_to_cpu(desc->addr),
+                              le32_to_cpu(desc->len),
+                              (flags & VRING_DESC_F_WRITE) ?
+                              DMA_FROM_DEVICE : DMA_TO_DEVICE);
+       }
+}
+
+static struct vring_packed_desc *alloc_indirect_packed(unsigned int total_sg,
+                                                      gfp_t gfp)
+{
+       struct vring_packed_desc *desc;
+
+       /*
+        * We require lowmem mappings for the descriptors because
+        * otherwise virt_to_phys will give us bogus addresses in the
+        * virtqueue.
+        */
+       gfp &= ~__GFP_HIGHMEM;
+
+       desc = kmalloc_array(total_sg, sizeof(struct vring_packed_desc), gfp);
+
+       return desc;
+}
+
+static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
+                                      struct scatterlist *sgs[],
+                                      unsigned int total_sg,
+                                      unsigned int out_sgs,
+                                      unsigned int in_sgs,
+                                      void *data,
+                                      gfp_t gfp)
+{
+       struct vring_packed_desc *desc;
+       struct scatterlist *sg;
+       unsigned int i, n, err_idx;
+       u16 head, id;
+       dma_addr_t addr;
+
+       head = vq->packed.next_avail_idx;
+       desc = alloc_indirect_packed(total_sg, gfp);
+
+       if (unlikely(vq->vq.num_free < 1)) {
+               pr_debug("Can't add buf len 1 - avail = 0\n");
+               END_USE(vq);
+               return -ENOSPC;
+       }
+
+       i = 0;
+       id = vq->free_head;
+       BUG_ON(id == vq->packed.vring.num);
+
+       for (n = 0; n < out_sgs + in_sgs; n++) {
+               for (sg = sgs[n]; sg; sg = sg_next(sg)) {
+                       addr = vring_map_one_sg(vq, sg, n < out_sgs ?
+                                       DMA_TO_DEVICE : DMA_FROM_DEVICE);
+                       if (vring_mapping_error(vq, addr))
+                               goto unmap_release;
+
+                       desc[i].flags = cpu_to_le16(n < out_sgs ?
+                                               0 : VRING_DESC_F_WRITE);
+                       desc[i].addr = cpu_to_le64(addr);
+                       desc[i].len = cpu_to_le32(sg->length);
+                       i++;
+               }
+       }
+
+       /* Now that the indirect table is filled in, map it. */
+       addr = vring_map_single(vq, desc,
+                       total_sg * sizeof(struct vring_packed_desc),
+                       DMA_TO_DEVICE);
+       if (vring_mapping_error(vq, addr))
+               goto unmap_release;
+
+       vq->packed.vring.desc[head].addr = cpu_to_le64(addr);
+       vq->packed.vring.desc[head].len = cpu_to_le32(total_sg *
+                               sizeof(struct vring_packed_desc));
+       vq->packed.vring.desc[head].id = cpu_to_le16(id);
+
+       if (vq->use_dma_api) {
+               vq->packed.desc_extra[id].addr = addr;
+               vq->packed.desc_extra[id].len = total_sg *
+                               sizeof(struct vring_packed_desc);
+               vq->packed.desc_extra[id].flags = VRING_DESC_F_INDIRECT |
+                                                 vq->packed.avail_used_flags;
+       }
+
+       /*
+        * A driver MUST NOT make the first descriptor in the list
+        * available before all subsequent descriptors comprising
+        * the list are made available.
+        */
+       virtio_wmb(vq->weak_barriers);
+       vq->packed.vring.desc[head].flags = cpu_to_le16(VRING_DESC_F_INDIRECT |
+                                               vq->packed.avail_used_flags);
+
+       /* We're using some buffers from the free list. */
+       vq->vq.num_free -= 1;
+
+       /* Update free pointer */
+       n = head + 1;
+       if (n >= vq->packed.vring.num) {
+               n = 0;
+               vq->packed.avail_wrap_counter ^= 1;
+               vq->packed.avail_used_flags ^=
+                               1 << VRING_PACKED_DESC_F_AVAIL |
+                               1 << VRING_PACKED_DESC_F_USED;
+       }
+       vq->packed.next_avail_idx = n;
+       vq->free_head = vq->packed.desc_state[id].next;
+
+       /* Store token and indirect buffer state. */
+       vq->packed.desc_state[id].num = 1;
+       vq->packed.desc_state[id].data = data;
+       vq->packed.desc_state[id].indir_desc = desc;
+       vq->packed.desc_state[id].last = id;
+
+       vq->num_added += 1;
+
+       pr_debug("Added buffer head %i to %p\n", head, vq);
+       END_USE(vq);
+
+       return 0;
+
+unmap_release:
+       err_idx = i;
+
+       for (i = 0; i < err_idx; i++)
+               vring_unmap_desc_packed(vq, &desc[i]);
+
+       kfree(desc);
+
+       END_USE(vq);
+       return -EIO;
+}
+
+static inline int virtqueue_add_packed(struct virtqueue *_vq,
+                                      struct scatterlist *sgs[],
+                                      unsigned int total_sg,
+                                      unsigned int out_sgs,
+                                      unsigned int in_sgs,
+                                      void *data,
+                                      void *ctx,
+                                      gfp_t gfp)
+{
+       struct vring_virtqueue *vq = to_vvq(_vq);
+       struct vring_packed_desc *desc;
+       struct scatterlist *sg;
+       unsigned int i, n, c, descs_used, err_idx;
+       __le16 uninitialized_var(head_flags), flags;
+       u16 head, id, uninitialized_var(prev), curr, avail_used_flags;
+
+       START_USE(vq);
+
+       BUG_ON(data == NULL);
+       BUG_ON(ctx && vq->indirect);
+
+       if (unlikely(vq->broken)) {
+               END_USE(vq);
+               return -EIO;
+       }
+
+       LAST_ADD_TIME_UPDATE(vq);
+
+       BUG_ON(total_sg == 0);
+
+       if (virtqueue_use_indirect(_vq, total_sg))
+               return virtqueue_add_indirect_packed(vq, sgs, total_sg,
+                               out_sgs, in_sgs, data, gfp);
+
+       head = vq->packed.next_avail_idx;
+       avail_used_flags = vq->packed.avail_used_flags;
+
+       WARN_ON_ONCE(total_sg > vq->packed.vring.num && !vq->indirect);
+
+       desc = vq->packed.vring.desc;
+       i = head;
+       descs_used = total_sg;
+
+       if (unlikely(vq->vq.num_free < descs_used)) {
+               pr_debug("Can't add buf len %i - avail = %i\n",
+                        descs_used, vq->vq.num_free);
+               END_USE(vq);
+               return -ENOSPC;
+       }
+
+       id = vq->free_head;
+       BUG_ON(id == vq->packed.vring.num);
+
+       curr = id;
+       c = 0;
+       for (n = 0; 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, n < out_sgs ?
+                                       DMA_TO_DEVICE : DMA_FROM_DEVICE);
+                       if (vring_mapping_error(vq, addr))
+                               goto unmap_release;
+
+                       flags = cpu_to_le16(vq->packed.avail_used_flags |
+                                   (++c == total_sg ? 0 : VRING_DESC_F_NEXT) |
+                                   (n < out_sgs ? 0 : VRING_DESC_F_WRITE));
+                       if (i == head)
+                               head_flags = flags;
+                       else
+                               desc[i].flags = flags;
+
+                       desc[i].addr = cpu_to_le64(addr);
+                       desc[i].len = cpu_to_le32(sg->length);
+                       desc[i].id = cpu_to_le16(id);
+
+                       if (unlikely(vq->use_dma_api)) {
+                               vq->packed.desc_extra[curr].addr = addr;
+                               vq->packed.desc_extra[curr].len = sg->length;
+                               vq->packed.desc_extra[curr].flags =
+                                       le16_to_cpu(flags);
+                       }
+                       prev = curr;
+                       curr = vq->packed.desc_state[curr].next;
+
+                       if ((unlikely(++i >= vq->packed.vring.num))) {
+                               i = 0;
+                               vq->packed.avail_used_flags ^=
+                                       1 << VRING_PACKED_DESC_F_AVAIL |
+                                       1 << VRING_PACKED_DESC_F_USED;
+                       }
+               }
+       }
+
+       if (i < head)
+               vq->packed.avail_wrap_counter ^= 1;
+
+       /* We're using some buffers from the free list. */
+       vq->vq.num_free -= descs_used;
+
+       /* Update free pointer */
+       vq->packed.next_avail_idx = i;
+       vq->free_head = curr;
+
+       /* Store token. */
+       vq->packed.desc_state[id].num = descs_used;
+       vq->packed.desc_state[id].data = data;
+       vq->packed.desc_state[id].indir_desc = ctx;
+       vq->packed.desc_state[id].last = prev;
+
+       /*
+        * A driver MUST NOT make the first descriptor in the list
+        * available before all subsequent descriptors comprising
+        * the list are made available.
+        */
+       virtio_wmb(vq->weak_barriers);
+       vq->packed.vring.desc[head].flags = head_flags;
+       vq->num_added += descs_used;
+
+       pr_debug("Added buffer head %i to %p\n", head, vq);
+       END_USE(vq);
+
+       return 0;
+
+unmap_release:
+       err_idx = i;
+       i = head;
+
+       vq->packed.avail_used_flags = avail_used_flags;
+
+       for (n = 0; n < total_sg; n++) {
+               if (i == err_idx)
+                       break;
+               vring_unmap_desc_packed(vq, &desc[i]);
+               i++;
+               if (i >= vq->packed.vring.num)
+                       i = 0;
+       }
+
+       END_USE(vq);
+       return -EIO;
+}
+
+static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq)
+{
+       struct vring_virtqueue *vq = to_vvq(_vq);
+       u16 flags;
+       bool needs_kick;
+       union {
+               struct {
+                       __le16 off_wrap;
+                       __le16 flags;
+               };
+               u32 u32;
+       } snapshot;
+
+       START_USE(vq);
+
+       /*
+        * We need to expose the new flags value before checking notification
+        * suppressions.
+        */
+       virtio_mb(vq->weak_barriers);
+
+       vq->num_added = 0;
+
+       snapshot.u32 = *(u32 *)vq->packed.vring.device;
+       flags = le16_to_cpu(snapshot.flags);
+
+       LAST_ADD_TIME_CHECK(vq);
+       LAST_ADD_TIME_INVALID(vq);
+
+       needs_kick = (flags != VRING_PACKED_EVENT_FLAG_DISABLE);
+       END_USE(vq);
+       return needs_kick;
+}
+
+static void detach_buf_packed(struct vring_virtqueue *vq,
+                             unsigned int id, void **ctx)
+{
+       struct vring_desc_state_packed *state = NULL;
+       struct vring_packed_desc *desc;
+       unsigned int i, curr;
+
+       state = &vq->packed.desc_state[id];
+
+       /* Clear data ptr. */
+       state->data = NULL;
+
+       vq->packed.desc_state[state->last].next = vq->free_head;
+       vq->free_head = id;
+       vq->vq.num_free += state->num;
+
+       if (unlikely(vq->use_dma_api)) {
+               curr = id;
+               for (i = 0; i < state->num; i++) {
+                       vring_unmap_state_packed(vq,
+                               &vq->packed.desc_extra[curr]);
+                       curr = vq->packed.desc_state[curr].next;
+               }
+       }
+
+       if (vq->indirect) {
+               u32 len;
+
+               /* Free the indirect table, if any, now that it's unmapped. */
+               desc = state->indir_desc;
+               if (!desc)
+                       return;
+
+               if (vq->use_dma_api) {
+                       len = vq->packed.desc_extra[id].len;
+                       for (i = 0; i < len / sizeof(struct vring_packed_desc);
+                                       i++)
+                               vring_unmap_desc_packed(vq, &desc[i]);
+               }
+               kfree(desc);
+               state->indir_desc = NULL;
+       } else if (ctx) {
+               *ctx = state->indir_desc;
+       }
+}
+
+static inline bool is_used_desc_packed(const struct vring_virtqueue *vq,
+                                      u16 idx, bool used_wrap_counter)
+{
+       bool avail, used;
+       u16 flags;
+
+       flags = le16_to_cpu(vq->packed.vring.desc[idx].flags);
+       avail = !!(flags & (1 << VRING_PACKED_DESC_F_AVAIL));
+       used = !!(flags & (1 << VRING_PACKED_DESC_F_USED));
+
+       return avail == used && used == used_wrap_counter;
+}
+
+static inline bool more_used_packed(const struct vring_virtqueue *vq)
+{
+       return is_used_desc_packed(vq, vq->last_used_idx,
+                       vq->packed.used_wrap_counter);
+}
+
+static void *virtqueue_get_buf_ctx_packed(struct virtqueue *_vq,
+                                         unsigned int *len,
+                                         void **ctx)
+{
+       struct vring_virtqueue *vq = to_vvq(_vq);
+       u16 last_used, id;
+       void *ret;
+
+       START_USE(vq);
+
+       if (unlikely(vq->broken)) {
+               END_USE(vq);
+               return NULL;
+       }
+
+       if (!more_used_packed(vq)) {
+               pr_debug("No more buffers in queue\n");
+               END_USE(vq);
+               return NULL;
+       }
+
+       /* Only get used elements after they have been exposed by host. */
+       virtio_rmb(vq->weak_barriers);
+
+       last_used = vq->last_used_idx;
+       id = le16_to_cpu(vq->packed.vring.desc[last_used].id);
+       *len = le32_to_cpu(vq->packed.vring.desc[last_used].len);
+
+       if (unlikely(id >= vq->packed.vring.num)) {
+               BAD_RING(vq, "id %u out of range\n", id);
+               return NULL;
+       }
+       if (unlikely(!vq->packed.desc_state[id].data)) {
+               BAD_RING(vq, "id %u is not a head!\n", id);
+               return NULL;
+       }
+
+       /* detach_buf_packed clears data, so grab it now. */
+       ret = vq->packed.desc_state[id].data;
+       detach_buf_packed(vq, id, ctx);
+
+       vq->last_used_idx += vq->packed.desc_state[id].num;
+       if (unlikely(vq->last_used_idx >= vq->packed.vring.num)) {
+               vq->last_used_idx -= vq->packed.vring.num;
+               vq->packed.used_wrap_counter ^= 1;
+       }
+
+       LAST_ADD_TIME_INVALID(vq);
+
+       END_USE(vq);
+       return ret;
+}
+
+static void virtqueue_disable_cb_packed(struct virtqueue *_vq)
+{
+       struct vring_virtqueue *vq = to_vvq(_vq);
+
+       if (vq->packed.event_flags_shadow != VRING_PACKED_EVENT_FLAG_DISABLE) {
+               vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_DISABLE;
+               vq->packed.vring.driver->flags =
+                       cpu_to_le16(vq->packed.event_flags_shadow);
+       }
+}
+
+static unsigned virtqueue_enable_cb_prepare_packed(struct virtqueue *_vq)
+{
+       struct vring_virtqueue *vq = to_vvq(_vq);
+
+       START_USE(vq);
+
+       /*
+        * We optimistically turn back on interrupts, then check if there was
+        * more to do.
+        */
+
+       if (vq->packed.event_flags_shadow == VRING_PACKED_EVENT_FLAG_DISABLE) {
+               vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_ENABLE;
+               vq->packed.vring.driver->flags =
+                               cpu_to_le16(vq->packed.event_flags_shadow);
+       }
+
+       END_USE(vq);
+       return vq->last_used_idx | ((u16)vq->packed.used_wrap_counter <<
+                       VRING_PACKED_EVENT_F_WRAP_CTR);
+}
+
+static bool virtqueue_poll_packed(struct virtqueue *_vq, u16 off_wrap)
+{
+       struct vring_virtqueue *vq = to_vvq(_vq);
+       bool wrap_counter;
+       u16 used_idx;
+
+       wrap_counter = off_wrap >> VRING_PACKED_EVENT_F_WRAP_CTR;
+       used_idx = off_wrap & ~(1 << VRING_PACKED_EVENT_F_WRAP_CTR);
+
+       return is_used_desc_packed(vq, used_idx, wrap_counter);
+}
+
+static bool virtqueue_enable_cb_delayed_packed(struct virtqueue *_vq)
+{
+       struct vring_virtqueue *vq = to_vvq(_vq);
+       u16 used_idx, wrap_counter;
+
+       START_USE(vq);
+
+       /*
+        * We optimistically turn back on interrupts, then check if there was
+        * more to do.
+        */
+
+       used_idx = vq->last_used_idx;
+       wrap_counter = vq->packed.used_wrap_counter;
+
+       if (vq->packed.event_flags_shadow == VRING_PACKED_EVENT_FLAG_DISABLE) {
+               vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_ENABLE;
+               vq->packed.vring.driver->flags =
+                               cpu_to_le16(vq->packed.event_flags_shadow);
+       }
+
+       /*
+        * We need to update event suppression structure first
+        * before re-checking for more used buffers.
+        */
+       virtio_mb(vq->weak_barriers);
+
+       if (is_used_desc_packed(vq, used_idx, wrap_counter)) {
+               END_USE(vq);
+               return false;
+       }
+
+       END_USE(vq);
+       return true;
+}
+
+static void *virtqueue_detach_unused_buf_packed(struct virtqueue *_vq)
+{
+       struct vring_virtqueue *vq = to_vvq(_vq);
+       unsigned int i;
+       void *buf;
+
+       START_USE(vq);
+
+       for (i = 0; i < vq->packed.vring.num; i++) {
+               if (!vq->packed.desc_state[i].data)
+                       continue;
+               /* detach_buf clears data, so grab it now. */
+               buf = vq->packed.desc_state[i].data;
+               detach_buf_packed(vq, i, NULL);
+               END_USE(vq);
+               return buf;
+       }
+       /* That should have freed everything. */
+       BUG_ON(vq->vq.num_free != vq->packed.vring.num);
+
+       END_USE(vq);
+       return NULL;
+}
+
+static struct virtqueue *vring_create_virtqueue_packed(
+       unsigned int index,
+       unsigned int num,
+       unsigned int vring_align,
+       struct virtio_device *vdev,
+       bool weak_barriers,
+       bool may_reduce_num,
+       bool context,
+       bool (*notify)(struct virtqueue *),
+       void (*callback)(struct virtqueue *),
+       const char *name)
+{
+       struct vring_virtqueue *vq;
+       struct vring_packed_desc *ring;
+       struct vring_packed_desc_event *driver, *device;
+       dma_addr_t ring_dma_addr, driver_event_dma_addr, device_event_dma_addr;
+       size_t ring_size_in_bytes, event_size_in_bytes;
+       unsigned int i;
+
+       ring_size_in_bytes = num * sizeof(struct vring_packed_desc);
+
+       ring = vring_alloc_queue(vdev, ring_size_in_bytes,
+                                &ring_dma_addr,
+                                GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
+       if (!ring)
+               goto err_ring;
+
+       event_size_in_bytes = sizeof(struct vring_packed_desc_event);
+
+       driver = vring_alloc_queue(vdev, event_size_in_bytes,
+                                  &driver_event_dma_addr,
+                                  GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
+       if (!driver)
+               goto err_driver;
+
+       device = vring_alloc_queue(vdev, event_size_in_bytes,
+                                  &device_event_dma_addr,
+                                  GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
+       if (!device)
+               goto err_device;
+
+       vq = kmalloc(sizeof(*vq), GFP_KERNEL);
+       if (!vq)
+               goto err_vq;
+
+       vq->vq.callback = callback;
+       vq->vq.vdev = vdev;
+       vq->vq.name = name;
+       vq->vq.num_free = num;
+       vq->vq.index = index;
+       vq->we_own_ring = true;
+       vq->notify = notify;
+       vq->weak_barriers = weak_barriers;
+       vq->broken = false;
+       vq->last_used_idx = 0;
+       vq->num_added = 0;
+       vq->packed_ring = true;
+       vq->use_dma_api = vring_use_dma_api(vdev);
+       list_add_tail(&vq->vq.list, &vdev->vqs);
+#ifdef DEBUG
+       vq->in_use = false;
+       vq->last_add_time_valid = false;
+#endif
+
+       vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) &&
+               !context;
+       vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
+
+       vq->packed.ring_dma_addr = ring_dma_addr;
+       vq->packed.driver_event_dma_addr = driver_event_dma_addr;
+       vq->packed.device_event_dma_addr = device_event_dma_addr;
+
+       vq->packed.ring_size_in_bytes = ring_size_in_bytes;
+       vq->packed.event_size_in_bytes = event_size_in_bytes;
+
+       vq->packed.vring.num = num;
+       vq->packed.vring.desc = ring;
+       vq->packed.vring.driver = driver;
+       vq->packed.vring.device = device;
+
+       vq->packed.next_avail_idx = 0;
+       vq->packed.avail_wrap_counter = 1;
+       vq->packed.used_wrap_counter = 1;
+       vq->packed.event_flags_shadow = 0;
+       vq->packed.avail_used_flags = 1 << VRING_PACKED_DESC_F_AVAIL;
+
+       vq->packed.desc_state = kmalloc_array(num,
+                       sizeof(struct vring_desc_state_packed),
+                       GFP_KERNEL);
+       if (!vq->packed.desc_state)
+               goto err_desc_state;
+
+       memset(vq->packed.desc_state, 0,
+               num * sizeof(struct vring_desc_state_packed));
+
+       /* Put everything in free lists. */
+       vq->free_head = 0;
+       for (i = 0; i < num-1; i++)
+               vq->packed.desc_state[i].next = i + 1;
+
+       vq->packed.desc_extra = kmalloc_array(num,
+                       sizeof(struct vring_desc_extra_packed),
+                       GFP_KERNEL);
+       if (!vq->packed.desc_extra)
+               goto err_desc_extra;
+
+       memset(vq->packed.desc_extra, 0,
+               num * sizeof(struct vring_desc_extra_packed));
+
+       /* No callback?  Tell other side not to bother us. */
+       if (!callback) {
+               vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_DISABLE;
+               vq->packed.vring.driver->flags =
+                       cpu_to_le16(vq->packed.event_flags_shadow);
+       }
+
+       return &vq->vq;
+
+err_desc_extra:
+       kfree(vq->packed.desc_state);
+err_desc_state:
+       kfree(vq);
+err_vq:
+       vring_free_queue(vdev, event_size_in_bytes, device, ring_dma_addr);
+err_device:
+       vring_free_queue(vdev, event_size_in_bytes, driver, ring_dma_addr);
+err_driver:
+       vring_free_queue(vdev, ring_size_in_bytes, ring, ring_dma_addr);
+err_ring:
+       return NULL;
+}
+
+
 /*
  * Generic functions and exported symbols.
  */
@@ -853,8 +1622,12 @@ static inline int virtqueue_add(struct virtqueue *_vq,
                                void *ctx,
                                gfp_t gfp)
 {
-       return virtqueue_add_split(_vq, sgs, total_sg,
-                                  out_sgs, in_sgs, data, ctx, gfp);
+       struct vring_virtqueue *vq = to_vvq(_vq);
+
+       return vq->packed_ring ? virtqueue_add_packed(_vq, sgs, total_sg,
+                                       out_sgs, in_sgs, data, ctx, gfp) :
+                                virtqueue_add_split(_vq, sgs, total_sg,
+                                       out_sgs, in_sgs, data, ctx, gfp);
 }
 
 /**
@@ -973,7 +1746,10 @@ EXPORT_SYMBOL_GPL(virtqueue_add_inbuf_ctx);
  */
 bool virtqueue_kick_prepare(struct virtqueue *_vq)
 {
-       return virtqueue_kick_prepare_split(_vq);
+       struct vring_virtqueue *vq = to_vvq(_vq);
+
+       return vq->packed_ring ? virtqueue_kick_prepare_packed(_vq) :
+                                virtqueue_kick_prepare_split(_vq);
 }
 EXPORT_SYMBOL_GPL(virtqueue_kick_prepare);
 
@@ -1040,7 +1816,10 @@ EXPORT_SYMBOL_GPL(virtqueue_kick);
 void *virtqueue_get_buf_ctx(struct virtqueue *_vq, unsigned int *len,
                            void **ctx)
 {
-       return virtqueue_get_buf_ctx_split(_vq, len, ctx);
+       struct vring_virtqueue *vq = to_vvq(_vq);
+
+       return vq->packed_ring ? virtqueue_get_buf_ctx_packed(_vq, len, ctx) :
+                                virtqueue_get_buf_ctx_split(_vq, len, ctx);
 }
 EXPORT_SYMBOL_GPL(virtqueue_get_buf_ctx);
 
@@ -1049,7 +1828,6 @@ void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len)
        return virtqueue_get_buf_ctx(_vq, len, NULL);
 }
 EXPORT_SYMBOL_GPL(virtqueue_get_buf);
-
 /**
  * virtqueue_disable_cb - disable callbacks
  * @vq: the struct virtqueue we're talking about.
@@ -1061,7 +1839,12 @@ EXPORT_SYMBOL_GPL(virtqueue_get_buf);
  */
 void virtqueue_disable_cb(struct virtqueue *_vq)
 {
-       virtqueue_disable_cb_split(_vq);
+       struct vring_virtqueue *vq = to_vvq(_vq);
+
+       if (vq->packed_ring)
+               virtqueue_disable_cb_packed(_vq);
+       else
+               virtqueue_disable_cb_split(_vq);
 }
 EXPORT_SYMBOL_GPL(virtqueue_disable_cb);
 
@@ -1079,7 +1862,10 @@ EXPORT_SYMBOL_GPL(virtqueue_disable_cb);
  */
 unsigned virtqueue_enable_cb_prepare(struct virtqueue *_vq)
 {
-       return virtqueue_enable_cb_prepare_split(_vq);
+       struct vring_virtqueue *vq = to_vvq(_vq);
+
+       return vq->packed_ring ? virtqueue_enable_cb_prepare_packed(_vq) :
+                                virtqueue_enable_cb_prepare_split(_vq);
 }
 EXPORT_SYMBOL_GPL(virtqueue_enable_cb_prepare);
 
@@ -1097,7 +1883,8 @@ bool virtqueue_poll(struct virtqueue *_vq, unsigned last_used_idx)
        struct vring_virtqueue *vq = to_vvq(_vq);
 
        virtio_mb(vq->weak_barriers);
-       return virtqueue_poll_split(_vq, last_used_idx);
+       return vq->packed_ring ? virtqueue_poll_packed(_vq, last_used_idx) :
+                                virtqueue_poll_split(_vq, last_used_idx);
 }
 EXPORT_SYMBOL_GPL(virtqueue_poll);
 
@@ -1135,7 +1922,10 @@ EXPORT_SYMBOL_GPL(virtqueue_enable_cb);
  */
 bool virtqueue_enable_cb_delayed(struct virtqueue *_vq)
 {
-       return virtqueue_enable_cb_delayed_split(_vq);
+       struct vring_virtqueue *vq = to_vvq(_vq);
+
+       return vq->packed_ring ? virtqueue_enable_cb_delayed_packed(_vq) :
+                                virtqueue_enable_cb_delayed_split(_vq);
 }
 EXPORT_SYMBOL_GPL(virtqueue_enable_cb_delayed);
 
@@ -1149,13 +1939,16 @@ EXPORT_SYMBOL_GPL(virtqueue_enable_cb_delayed);
  */
 void *virtqueue_detach_unused_buf(struct virtqueue *_vq)
 {
-       return virtqueue_detach_unused_buf_split(_vq);
+       struct vring_virtqueue *vq = to_vvq(_vq);
+
+       return vq->packed_ring ? virtqueue_detach_unused_buf_packed(_vq) :
+                                virtqueue_detach_unused_buf_split(_vq);
 }
 EXPORT_SYMBOL_GPL(virtqueue_detach_unused_buf);
 
 static inline bool more_used(const struct vring_virtqueue *vq)
 {
-       return more_used_split(vq);
+       return vq->packed_ring ? more_used_packed(vq) : more_used_split(vq);
 }
 
 irqreturn_t vring_interrupt(int irq, void *_vq)
@@ -1178,6 +1971,7 @@ irqreturn_t vring_interrupt(int irq, void *_vq)
 }
 EXPORT_SYMBOL_GPL(vring_interrupt);
 
+/* Only available for split ring */
 struct virtqueue *__vring_new_virtqueue(unsigned int index,
                                        struct vring vring,
                                        struct virtio_device *vdev,
@@ -1190,10 +1984,14 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
        unsigned int i;
        struct vring_virtqueue *vq;
 
+       if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED))
+               return NULL;
+
        vq = kmalloc(sizeof(*vq), GFP_KERNEL);
        if (!vq)
                return NULL;
 
+       vq->packed_ring = false;
        vq->vq.callback = callback;
        vq->vq.vdev = vdev;
        vq->vq.name = name;
@@ -1261,12 +2059,19 @@ struct virtqueue *vring_create_virtqueue(
        void (*callback)(struct virtqueue *),
        const char *name)
 {
+
+       if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED))
+               return vring_create_virtqueue_packed(index, num, vring_align,
+                               vdev, weak_barriers, may_reduce_num,
+                               context, notify, callback, name);
+
        return vring_create_virtqueue_split(index, num, vring_align,
                        vdev, weak_barriers, may_reduce_num,
                        context, notify, callback, name);
 }
 EXPORT_SYMBOL_GPL(vring_create_virtqueue);
 
+/* Only available for split ring */
 struct virtqueue *vring_new_virtqueue(unsigned int index,
                                      unsigned int num,
                                      unsigned int vring_align,
@@ -1279,6 +2084,10 @@ struct virtqueue *vring_new_virtqueue(unsigned int index,
                                      const char *name)
 {
        struct vring vring;
+
+       if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED))
+               return NULL;
+
        vring_init(&vring, num, pages, vring_align);
        return __vring_new_virtqueue(index, vring, vdev, weak_barriers, context,
                                     notify, callback, name);
@@ -1290,11 +2099,32 @@ void vring_del_virtqueue(struct virtqueue *_vq)
        struct vring_virtqueue *vq = to_vvq(_vq);
 
        if (vq->we_own_ring) {
-               vring_free_queue(vq->vq.vdev,
-                                vq->split.queue_size_in_bytes,
-                                vq->split.vring.desc,
-                                vq->split.queue_dma_addr);
-               kfree(vq->split.desc_state);
+               if (vq->packed_ring) {
+                       vring_free_queue(vq->vq.vdev,
+                                        vq->packed.ring_size_in_bytes,
+                                        vq->packed.vring.desc,
+                                        vq->packed.ring_dma_addr);
+
+                       vring_free_queue(vq->vq.vdev,
+                                        vq->packed.event_size_in_bytes,
+                                        vq->packed.vring.driver,
+                                        vq->packed.driver_event_dma_addr);
+
+                       vring_free_queue(vq->vq.vdev,
+                                        vq->packed.event_size_in_bytes,
+                                        vq->packed.vring.device,
+                                        vq->packed.device_event_dma_addr);
+
+                       kfree(vq->packed.desc_state);
+                       kfree(vq->packed.desc_extra);
+               } else {
+                       vring_free_queue(vq->vq.vdev,
+                                        vq->split.queue_size_in_bytes,
+                                        vq->split.vring.desc,
+                                        vq->split.queue_dma_addr);
+
+                       kfree(vq->split.desc_state);
+               }
        }
        list_del(&_vq->list);
        kfree(vq);
@@ -1336,7 +2166,7 @@ unsigned int virtqueue_get_vring_size(struct virtqueue *_vq)
 
        struct vring_virtqueue *vq = to_vvq(_vq);
 
-       return vq->split.vring.num;
+       return vq->packed_ring ? vq->packed.vring.num : vq->split.vring.num;
 }
 EXPORT_SYMBOL_GPL(virtqueue_get_vring_size);
 
@@ -1369,6 +2199,9 @@ dma_addr_t virtqueue_get_desc_addr(struct virtqueue *_vq)
 
        BUG_ON(!vq->we_own_ring);
 
+       if (vq->packed_ring)
+               return vq->packed.ring_dma_addr;
+
        return vq->split.queue_dma_addr;
 }
 EXPORT_SYMBOL_GPL(virtqueue_get_desc_addr);
@@ -1379,6 +2212,9 @@ dma_addr_t virtqueue_get_avail_addr(struct virtqueue *_vq)
 
        BUG_ON(!vq->we_own_ring);
 
+       if (vq->packed_ring)
+               return vq->packed.driver_event_dma_addr;
+
        return vq->split.queue_dma_addr +
                ((char *)vq->split.vring.avail - (char *)vq->split.vring.desc);
 }
@@ -1390,11 +2226,15 @@ dma_addr_t virtqueue_get_used_addr(struct virtqueue *_vq)
 
        BUG_ON(!vq->we_own_ring);
 
+       if (vq->packed_ring)
+               return vq->packed.device_event_dma_addr;
+
        return vq->split.queue_dma_addr +
                ((char *)vq->split.vring.used - (char *)vq->split.vring.desc);
 }
 EXPORT_SYMBOL_GPL(virtqueue_get_used_addr);
 
+/* Only available for split ring */
 const struct vring *virtqueue_get_vring(struct virtqueue *vq)
 {
        return &to_vvq(vq)->split.vring;