[PATCH v7 0/8] Packed virtqueue for virtio

[PATCH v7 0/8] Packed virtqueue for virtio

[Eugenio Pérez]

Hi:

This is an updated version of packed virtqueue support based on Wei and Jason's
V6, mainly solving the clang leak detector error CI gave.

Please review.

Changes from V6:
- Commit reorder: Squash bugfix and sepparate big changes into smaller commits.

Changes from V5:
- Fix qemu's CI asan error.
- Move/copy rcu comments.
- Merge duplicated vdev->broken check between split and packet version.

Eugenio Pérez (2):
  virtio: Free blk virqueues at unrealize()
  virtio: Free rnd virqueue at unrealize()

Jason Wang (4):
  virtio: basic packed virtqueue support
  virtio: event suppression support for packed ring
  vhost_net: enable packed ring support
  virtio: add property to enable packed virtqueue

Wei Xu (2):
  virtio: basic structure for packed ring
  virtio: device/driver area size calculation refactor for split ring

 hw/block/virtio-blk.c       |    7 +-
 hw/char/virtio-serial-bus.c |    2 +-
 hw/net/vhost_net.c          |    2 +
 hw/scsi/virtio-scsi.c       |    3 +-
 hw/virtio/virtio-rng.c      |    1 +
 hw/virtio/virtio.c          | 1154 ++++++++++++++++++++++++++++++++++++++-----
 include/hw/virtio/virtio.h  |   14 +-
 7 files changed, 1045 insertions(+), 138 deletions(-)

-- 
2.16.5

[PATCH v7 1/8] virtio: basic structure for packed ring

[Eugenio Pérez]

From: Wei Xu <wexu@redhat.com>

Define packed ring structure according to Qemu nomenclature,
field data(wrap counter, etc) are also included.

Signed-off-by: Wei Xu <wexu@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Reviewed-by: Jens Freimann <jfreimann@redhat.com>
---
 hw/virtio/virtio.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 527df03bfd..fdac203cdf 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -43,6 +43,13 @@ typedef struct VRingDesc
     uint16_t next;
 } VRingDesc;
 
+typedef struct VRingPackedDesc {
+    uint64_t addr;
+    uint32_t len;
+    uint16_t id;
+    uint16_t flags;
+} VRingPackedDesc;
+
 typedef struct VRingAvail
 {
     uint16_t flags;
@@ -81,17 +88,25 @@ typedef struct VRing
     VRingMemoryRegionCaches *caches;
 } VRing;
 
+typedef struct VRingPackedDescEvent {
+    uint16_t off_wrap;
+    uint16_t flags;
+} VRingPackedDescEvent ;
+
 struct VirtQueue
 {
     VRing vring;
 
     /* Next head to pop */
     uint16_t last_avail_idx;
+    bool last_avail_wrap_counter;
 
     /* Last avail_idx read from VQ. */
     uint16_t shadow_avail_idx;
+    bool shadow_avail_wrap_counter;
 
     uint16_t used_idx;
+    bool used_wrap_counter;
 
     /* Last used index value we have signalled on */
     uint16_t signalled_used;
-- 
2.16.5

[PATCH v7 2/8] virtio: device/driver area size calculation refactor for split ring

[Eugenio Pérez]

From: Wei Xu <wexu@redhat.com>

There is slight size difference between split/packed rings.

This is the refactor of split ring as well as a helper to expanding
device and driver area size calculation for packed ring.

Signed-off-by: Wei Xu <wexu@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Reviewed-by: Jens Freimann <jfreimann@redhat.com>
---
 hw/virtio/virtio.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index fdac203cdf..74cc10fad9 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -159,10 +159,8 @@ static void virtio_init_region_cache(VirtIODevice *vdev, int n)
     VRingMemoryRegionCaches *old = vq->vring.caches;
     VRingMemoryRegionCaches *new = NULL;
     hwaddr addr, size;
-    int event_size;
     int64_t len;
 
-    event_size = virtio_vdev_has_feature(vq->vdev, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
 
     addr = vq->vring.desc;
     if (!addr) {
@@ -177,7 +175,7 @@ static void virtio_init_region_cache(VirtIODevice *vdev, int n)
         goto err_desc;
     }
 
-    size = virtio_queue_get_used_size(vdev, n) + event_size;
+    size = virtio_queue_get_used_size(vdev, n);
     len = address_space_cache_init(&new->used, vdev->dma_as,
                                    vq->vring.used, size, true);
     if (len < size) {
@@ -185,7 +183,7 @@ static void virtio_init_region_cache(VirtIODevice *vdev, int n)
         goto err_used;
     }
 
-    size = virtio_queue_get_avail_size(vdev, n) + event_size;
+    size = virtio_queue_get_avail_size(vdev, n);
     len = address_space_cache_init(&new->avail, vdev->dma_as,
                                    vq->vring.avail, size, false);
     if (len < size) {
@@ -2414,14 +2412,20 @@ hwaddr virtio_queue_get_desc_size(VirtIODevice *vdev, int n)
 
 hwaddr virtio_queue_get_avail_size(VirtIODevice *vdev, int n)
 {
+    int s;
+
+    s = virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
     return offsetof(VRingAvail, ring) +
-        sizeof(uint16_t) * vdev->vq[n].vring.num;
+        sizeof(uint16_t) * vdev->vq[n].vring.num + s;
 }
 
 hwaddr virtio_queue_get_used_size(VirtIODevice *vdev, int n)
 {
+    int s;
+
+    s = virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
     return offsetof(VRingUsed, ring) +
-        sizeof(VRingUsedElem) * vdev->vq[n].vring.num;
+        sizeof(VRingUsedElem) * vdev->vq[n].vring.num + s;
 }
 
 uint16_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n)
-- 
2.16.5

[PATCH v7 3/8] virtio: Free blk virqueues at unrealize()

[Eugenio Pérez]

The function virtio_del_queue was not called at unrealize() callback.

This was detected due to add an allocated element on the vq introduce
in future commits (used_elems) and running address sanitizer memory
leak detector.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 hw/block/virtio-blk.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index ed2ddebd2b..ba846fe9dc 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -1206,9 +1206,14 @@ static void virtio_blk_device_unrealize(DeviceState *dev, Error **errp)
 {
     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
     VirtIOBlock *s = VIRTIO_BLK(dev);
+    VirtIOBlkConf *conf = &s->conf;
+    unsigned i;
 
     virtio_blk_data_plane_destroy(s->dataplane);
     s->dataplane = NULL;
+    for (i = 0; i < conf->num_queues; i++) {
+        virtio_del_queue(vdev, i);
+    }
     qemu_del_vm_change_state_handler(s->change);
     blockdev_mark_auto_del(s->blk);
     virtio_cleanup(vdev);
-- 
2.16.5

[PATCH v7 4/8] virtio: Free rnd virqueue at unrealize()

[Eugenio Pérez]

The function virtio_del_queue was not called at unrealize() callback.

This was detected due to add an allocated element on the vq introduce
in future commits (used_elems) and running address sanitizer memory
leak detector.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 hw/virtio/virtio-rng.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hw/virtio/virtio-rng.c b/hw/virtio/virtio-rng.c
index e93bed020f..b498a20332 100644
--- a/hw/virtio/virtio-rng.c
+++ b/hw/virtio/virtio-rng.c
@@ -238,6 +238,7 @@ static void virtio_rng_device_unrealize(DeviceState *dev, Error **errp)
     qemu_del_vm_change_state_handler(vrng->vmstate);
     timer_del(vrng->rate_limit_timer);
     timer_free(vrng->rate_limit_timer);
+    virtio_del_queue(vdev, 0);
     virtio_cleanup(vdev);
 }
 
-- 
2.16.5

[PATCH v7 5/8] virtio: basic packed virtqueue support

[Eugenio Pérez]

From: Jason Wang <jasowang@redhat.com>

This patch implements basic support for the packed virtqueue. Compare
the split virtqueue which has three rings, packed virtqueue only have
one which is supposed to have better cache utilization and more
hardware friendly.

Please refer virtio specification for more information.

Signed-off-by: Wei Xu <wexu@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 hw/block/virtio-blk.c       |   2 +-
 hw/char/virtio-serial-bus.c |   2 +-
 hw/scsi/virtio-scsi.c       |   3 +-
 hw/virtio/virtio.c          | 901 ++++++++++++++++++++++++++++++++++++++++----
 include/hw/virtio/virtio.h  |  10 +-
 5 files changed, 836 insertions(+), 82 deletions(-)

diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index ba846fe9dc..7dbdeaaab9 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -1052,7 +1052,7 @@ static void virtio_blk_save_device(VirtIODevice *vdev, QEMUFile *f)
             qemu_put_be32(f, virtio_get_queue_index(req->vq));
         }
 
-        qemu_put_virtqueue_element(f, &req->elem);
+        qemu_put_virtqueue_element(vdev, f, &req->elem);
         req = req->next;
     }
     qemu_put_sbyte(f, 0);
diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c
index 4e0ed829ae..33259042a9 100644
--- a/hw/char/virtio-serial-bus.c
+++ b/hw/char/virtio-serial-bus.c
@@ -708,7 +708,7 @@ static void virtio_serial_save_device(VirtIODevice *vdev, QEMUFile *f)
         if (elem_popped) {
             qemu_put_be32s(f, &port->iov_idx);
             qemu_put_be64s(f, &port->iov_offset);
-            qemu_put_virtqueue_element(f, port->elem);
+            qemu_put_virtqueue_element(vdev, f, port->elem);
         }
     }
 }
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index ee52aa7d17..e8b2b64d09 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -190,11 +190,12 @@ static void virtio_scsi_save_request(QEMUFile *f, SCSIRequest *sreq)
 {
     VirtIOSCSIReq *req = sreq->hba_private;
     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(req->dev);
+    VirtIODevice *vdev = VIRTIO_DEVICE(req->dev);
     uint32_t n = virtio_get_queue_index(req->vq) - 2;
 
     assert(n < vs->conf.num_queues);
     qemu_put_be32s(f, &n);
-    qemu_put_virtqueue_element(f, &req->elem);
+    qemu_put_virtqueue_element(vdev, f, &req->elem);
 }
 
 static void *virtio_scsi_load_request(QEMUFile *f, SCSIRequest *sreq)
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 74cc10fad9..a694b4ab50 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -96,6 +96,7 @@ typedef struct VRingPackedDescEvent {
 struct VirtQueue
 {
     VRing vring;
+    VirtQueueElement *used_elems;
 
     /* Next head to pop */
     uint16_t last_avail_idx;
@@ -160,6 +161,7 @@ static void virtio_init_region_cache(VirtIODevice *vdev, int n)
     VRingMemoryRegionCaches *new = NULL;
     hwaddr addr, size;
     int64_t len;
+    bool packed;
 
 
     addr = vq->vring.desc;
@@ -168,8 +170,10 @@ static void virtio_init_region_cache(VirtIODevice *vdev, int n)
     }
     new = g_new0(VRingMemoryRegionCaches, 1);
     size = virtio_queue_get_desc_size(vdev, n);
+    packed = virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED) ?
+                                   true : false;
     len = address_space_cache_init(&new->desc, vdev->dma_as,
-                                   addr, size, false);
+                                   addr, size, packed);
     if (len < size) {
         virtio_error(vdev, "Cannot map desc");
         goto err_desc;
@@ -225,8 +229,8 @@ void virtio_queue_update_rings(VirtIODevice *vdev, int n)
 }
 
 /* Called within rcu_read_lock().  */
-static void vring_desc_read(VirtIODevice *vdev, VRingDesc *desc,
-                            MemoryRegionCache *cache, int i)
+static void vring_split_desc_read(VirtIODevice *vdev, VRingDesc *desc,
+                                  MemoryRegionCache *cache, int i)
 {
     address_space_read_cached(cache, i * sizeof(VRingDesc),
                               desc, sizeof(VRingDesc));
@@ -236,6 +240,7 @@ static void vring_desc_read(VirtIODevice *vdev, VRingDesc *desc,
     virtio_tswap16s(vdev, &desc->next);
 }
 
+/* Called within rcu_read_lock().  */
 static VRingMemoryRegionCaches *vring_get_region_caches(struct VirtQueue *vq)
 {
     VRingMemoryRegionCaches *caches = atomic_rcu_read(&vq->vring.caches);
@@ -370,6 +375,95 @@ int virtio_queue_ready(VirtQueue *vq)
     return vq->vring.avail != 0;
 }
 
+static void vring_packed_desc_read_flags(VirtIODevice *vdev,
+                                         uint16_t *flags,
+                                         MemoryRegionCache *cache,
+                                         int i)
+{
+    address_space_read_cached(cache,
+                              i * sizeof(VRingPackedDesc) +
+                              offsetof(VRingPackedDesc, flags),
+                              flags, sizeof(*flags));
+    virtio_tswap16s(vdev, flags);
+}
+
+static void vring_packed_desc_read(VirtIODevice *vdev,
+                                   VRingPackedDesc *desc,
+                                   MemoryRegionCache *cache,
+                                   int i, bool strict_order)
+{
+    hwaddr off = i * sizeof(VRingPackedDesc);
+
+    vring_packed_desc_read_flags(vdev, &desc->flags, cache, i);
+
+    if (strict_order) {
+        /* Make sure flags is read before the rest fields. */
+        smp_rmb();
+    }
+
+    address_space_read_cached(cache, off + offsetof(VRingPackedDesc, addr),
+                              &desc->addr, sizeof(desc->addr));
+    address_space_read_cached(cache, off + offsetof(VRingPackedDesc, id),
+                              &desc->id, sizeof(desc->id));
+    address_space_read_cached(cache, off + offsetof(VRingPackedDesc, len),
+                              &desc->len, sizeof(desc->len));
+    virtio_tswap64s(vdev, &desc->addr);
+    virtio_tswap16s(vdev, &desc->id);
+    virtio_tswap32s(vdev, &desc->len);
+}
+
+static void vring_packed_desc_write_data(VirtIODevice *vdev,
+                                         VRingPackedDesc *desc,
+                                         MemoryRegionCache *cache,
+                                         int i)
+{
+    hwaddr off_id = i * sizeof(VRingPackedDesc) +
+                    offsetof(VRingPackedDesc, id);
+    hwaddr off_len = i * sizeof(VRingPackedDesc) +
+                    offsetof(VRingPackedDesc, len);
+
+    virtio_tswap32s(vdev, &desc->len);
+    virtio_tswap16s(vdev, &desc->id);
+    address_space_write_cached(cache, off_id, &desc->id, sizeof(desc->id));
+    address_space_cache_invalidate(cache, off_id, sizeof(desc->id));
+    address_space_write_cached(cache, off_len, &desc->len, sizeof(desc->len));
+    address_space_cache_invalidate(cache, off_len, sizeof(desc->len));
+}
+
+static void vring_packed_desc_write_flags(VirtIODevice *vdev,
+                                          VRingPackedDesc *desc,
+                                          MemoryRegionCache *cache,
+                                          int i)
+{
+    hwaddr off = i * sizeof(VRingPackedDesc) + offsetof(VRingPackedDesc, flags);
+
+    virtio_tswap16s(vdev, &desc->flags);
+    address_space_write_cached(cache, off, &desc->flags, sizeof(desc->flags));
+    address_space_cache_invalidate(cache, off, sizeof(desc->flags));
+}
+
+static void vring_packed_desc_write(VirtIODevice *vdev,
+                                    VRingPackedDesc *desc,
+                                    MemoryRegionCache *cache,
+                                    int i, bool strict_order)
+{
+    vring_packed_desc_write_data(vdev, desc, cache, i);
+    if (strict_order) {
+        /* Make sure data is wrote before flags. */
+        smp_wmb();
+    }
+    vring_packed_desc_write_flags(vdev, desc, cache, i);
+}
+
+static inline bool is_desc_avail(uint16_t flags, bool wrap_counter)
+{
+    bool avail, used;
+
+    avail = !!(flags & (1 << VRING_PACKED_DESC_F_AVAIL));
+    used = !!(flags & (1 << VRING_PACKED_DESC_F_USED));
+    return (avail != used) && (avail == wrap_counter);
+}
+
 /* Fetch avail_idx from VQ memory only when we really need to know if
  * guest has added some buffers.
  * Called within rcu_read_lock().  */
@@ -390,7 +484,7 @@ static int virtio_queue_empty_rcu(VirtQueue *vq)
     return vring_avail_idx(vq) == vq->last_avail_idx;
 }
 
-int virtio_queue_empty(VirtQueue *vq)
+static int virtio_queue_split_empty(VirtQueue *vq)
 {
     bool empty;
 
@@ -412,6 +506,41 @@ int virtio_queue_empty(VirtQueue *vq)
     return empty;
 }
 
+static int virtio_queue_packed_empty_rcu(VirtQueue *vq)
+{
+    struct VRingPackedDesc desc;
+    VRingMemoryRegionCaches *cache;
+
+    if (unlikely(!vq->vring.desc)) {
+        return 1;
+    }
+
+    cache = vring_get_region_caches(vq);
+    vring_packed_desc_read_flags(vq->vdev, &desc.flags, &cache->desc,
+                                 vq->last_avail_idx);
+
+    return !is_desc_avail(desc.flags, vq->last_avail_wrap_counter);
+}
+
+static int virtio_queue_packed_empty(VirtQueue *vq)
+{
+    bool empty;
+
+    rcu_read_lock();
+    empty = virtio_queue_packed_empty_rcu(vq);
+    rcu_read_unlock();
+    return empty;
+}
+
+int virtio_queue_empty(VirtQueue *vq)
+{
+    if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
+        return virtio_queue_packed_empty(vq);
+    } else {
+        return virtio_queue_split_empty(vq);
+    }
+}
+
 static void virtqueue_unmap_sg(VirtQueue *vq, const VirtQueueElement *elem,
                                unsigned int len)
 {
@@ -449,10 +578,25 @@ static void virtqueue_unmap_sg(VirtQueue *vq, const VirtQueueElement *elem,
 void virtqueue_detach_element(VirtQueue *vq, const VirtQueueElement *elem,
                               unsigned int len)
 {
-    vq->inuse--;
+    vq->inuse -= elem->ndescs;
     virtqueue_unmap_sg(vq, elem, len);
 }
 
+static void virtqueue_split_rewind(VirtQueue *vq, unsigned int num)
+{
+    vq->last_avail_idx -= num;
+}
+
+static void virtqueue_packed_rewind(VirtQueue *vq, unsigned int num)
+{
+    if (vq->last_avail_idx < num) {
+        vq->last_avail_idx = vq->vring.num + vq->last_avail_idx - num;
+        vq->last_avail_wrap_counter ^= 1;
+    } else {
+        vq->last_avail_idx -= num;
+    }
+}
+
 /* virtqueue_unpop:
  * @vq: The #VirtQueue
  * @elem: The #VirtQueueElement
@@ -464,7 +608,13 @@ void virtqueue_detach_element(VirtQueue *vq, const VirtQueueElement *elem,
 void virtqueue_unpop(VirtQueue *vq, const VirtQueueElement *elem,
                      unsigned int len)
 {
-    vq->last_avail_idx--;
+
+    if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
+        virtqueue_packed_rewind(vq, 1);
+    } else {
+        virtqueue_split_rewind(vq, 1);
+    }
+
     virtqueue_detach_element(vq, elem, len);
 }
 
@@ -485,25 +635,21 @@ bool virtqueue_rewind(VirtQueue *vq, unsigned int num)
     if (num > vq->inuse) {
         return false;
     }
-    vq->last_avail_idx -= num;
+
     vq->inuse -= num;
+    if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
+        virtqueue_packed_rewind(vq, num);
+    } else {
+        virtqueue_split_rewind(vq, num);
+    }
     return true;
 }
 
-/* Called within rcu_read_lock().  */
-void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem,
+static void virtqueue_split_fill(VirtQueue *vq, const VirtQueueElement *elem,
                     unsigned int len, unsigned int idx)
 {
     VRingUsedElem uelem;
 
-    trace_virtqueue_fill(vq, elem, len, idx);
-
-    virtqueue_unmap_sg(vq, elem, len);
-
-    if (unlikely(vq->vdev->broken)) {
-        return;
-    }
-
     if (unlikely(!vq->vring.used)) {
         return;
     }
@@ -515,16 +661,72 @@ void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem,
     vring_used_write(vq, &uelem, idx);
 }
 
+static void virtqueue_packed_fill(VirtQueue *vq, const VirtQueueElement *elem,
+                                  unsigned int len, unsigned int idx)
+{
+    vq->used_elems[idx].index = elem->index;
+    vq->used_elems[idx].len = len;
+    vq->used_elems[idx].ndescs = elem->ndescs;
+}
+
+static void virtqueue_packed_fill_desc(VirtQueue *vq,
+                                       const VirtQueueElement *elem,
+                                       unsigned int idx,
+                                       bool strict_order)
+{
+    uint16_t head;
+    VRingMemoryRegionCaches *caches;
+    VRingPackedDesc desc = {
+        .id = elem->index,
+        .len = elem->len,
+    };
+    bool wrap_counter = vq->used_wrap_counter;
+
+    if (unlikely(!vq->vring.desc)) {
+        return;
+    }
+
+    head = vq->used_idx + idx;
+    if (head >= vq->vring.num) {
+        head -= vq->vring.num;
+        wrap_counter ^= 1;
+    }
+    if (wrap_counter) {
+        desc.flags |= (1 << VRING_PACKED_DESC_F_AVAIL);
+        desc.flags |= (1 << VRING_PACKED_DESC_F_USED);
+    } else {
+        desc.flags &= ~(1 << VRING_PACKED_DESC_F_AVAIL);
+        desc.flags &= ~(1 << VRING_PACKED_DESC_F_USED);
+    }
+
+    caches = vring_get_region_caches(vq);
+    vring_packed_desc_write(vq->vdev, &desc, &caches->desc, head, strict_order);
+}
+
 /* Called within rcu_read_lock().  */
-void virtqueue_flush(VirtQueue *vq, unsigned int count)
+void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem,
+                    unsigned int len, unsigned int idx)
 {
-    uint16_t old, new;
+    trace_virtqueue_fill(vq, elem, len, idx);
+
+    virtqueue_unmap_sg(vq, elem, len);
 
     if (unlikely(vq->vdev->broken)) {
-        vq->inuse -= count;
         return;
     }
 
+    if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
+        virtqueue_packed_fill(vq, elem, len, idx);
+    } else {
+        virtqueue_split_fill(vq, elem, len, idx);
+    }
+}
+
+/* Called within rcu_read_lock().  */
+static void virtqueue_split_flush(VirtQueue *vq, unsigned int count)
+{
+    uint16_t old, new;
+
     if (unlikely(!vq->vring.used)) {
         return;
     }
@@ -540,6 +742,43 @@ void virtqueue_flush(VirtQueue *vq, unsigned int count)
         vq->signalled_used_valid = false;
 }
 
+static void virtqueue_packed_flush(VirtQueue *vq, unsigned int count)
+{
+    unsigned int i, ndescs = 0;
+
+    if (unlikely(!vq->vring.desc)) {
+        return;
+    }
+
+    for (i = 1; i < count; i++) {
+        virtqueue_packed_fill_desc(vq, &vq->used_elems[i], i, false);
+        ndescs += vq->used_elems[i].ndescs;
+    }
+    virtqueue_packed_fill_desc(vq, &vq->used_elems[0], 0, true);
+    ndescs += vq->used_elems[0].ndescs;
+
+    vq->inuse -= ndescs;
+    vq->used_idx += ndescs;
+    if (vq->used_idx >= vq->vring.num) {
+        vq->used_idx -= vq->vring.num;
+        vq->used_wrap_counter ^= 1;
+    }
+}
+
+void virtqueue_flush(VirtQueue *vq, unsigned int count)
+{
+    if (unlikely(vq->vdev->broken)) {
+        vq->inuse -= count;
+        return;
+    }
+
+    if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
+        virtqueue_packed_flush(vq, count);
+    } else {
+        virtqueue_split_flush(vq, count);
+    }
+}
+
 void virtqueue_push(VirtQueue *vq, const VirtQueueElement *elem,
                     unsigned int len)
 {
@@ -592,9 +831,9 @@ enum {
     VIRTQUEUE_READ_DESC_MORE = 1,   /* more buffers in chain */
 };
 
-static int virtqueue_read_next_desc(VirtIODevice *vdev, VRingDesc *desc,
-                                    MemoryRegionCache *desc_cache, unsigned int max,
-                                    unsigned int *next)
+static int virtqueue_split_read_next_desc(VirtIODevice *vdev, VRingDesc *desc,
+                                          MemoryRegionCache *desc_cache,
+                                          unsigned int max, unsigned int *next)
 {
     /* If this descriptor says it doesn't chain, we're done. */
     if (!(desc->flags & VRING_DESC_F_NEXT)) {
@@ -611,13 +850,13 @@ static int virtqueue_read_next_desc(VirtIODevice *vdev, VRingDesc *desc,
         return VIRTQUEUE_READ_DESC_ERROR;
     }
 
-    vring_desc_read(vdev, desc, desc_cache, *next);
+    vring_split_desc_read(vdev, desc, desc_cache, *next);
     return VIRTQUEUE_READ_DESC_MORE;
 }
 
-void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes,
-                               unsigned int *out_bytes,
-                               unsigned max_in_bytes, unsigned max_out_bytes)
+static void virtqueue_split_get_avail_bytes(VirtQueue *vq,
+                            unsigned int *in_bytes, unsigned int *out_bytes,
+                            unsigned max_in_bytes, unsigned max_out_bytes)
 {
     VirtIODevice *vdev = vq->vdev;
     unsigned int max, idx;
@@ -627,27 +866,12 @@ void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes,
     int64_t len = 0;
     int rc;
 
-    if (unlikely(!vq->vring.desc)) {
-        if (in_bytes) {
-            *in_bytes = 0;
-        }
-        if (out_bytes) {
-            *out_bytes = 0;
-        }
-        return;
-    }
-
     rcu_read_lock();
     idx = vq->last_avail_idx;
     total_bufs = in_total = out_total = 0;
 
     max = vq->vring.num;
     caches = vring_get_region_caches(vq);
-    if (caches->desc.len < max * sizeof(VRingDesc)) {
-        virtio_error(vdev, "Cannot map descriptor ring");
-        goto err;
-    }
-
     while ((rc = virtqueue_num_heads(vq, idx)) > 0) {
         MemoryRegionCache *desc_cache = &caches->desc;
         unsigned int num_bufs;
@@ -660,7 +884,7 @@ void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes,
             goto err;
         }
 
-        vring_desc_read(vdev, &desc, desc_cache, i);
+        vring_split_desc_read(vdev, &desc, desc_cache, i);
 
         if (desc.flags & VRING_DESC_F_INDIRECT) {
             if (!desc.len || (desc.len % sizeof(VRingDesc))) {
@@ -686,7 +910,7 @@ void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes,
 
             max = desc.len / sizeof(VRingDesc);
             num_bufs = i = 0;
-            vring_desc_read(vdev, &desc, desc_cache, i);
+            vring_split_desc_read(vdev, &desc, desc_cache, i);
         }
 
         do {
@@ -705,7 +929,7 @@ void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes,
                 goto done;
             }
 
-            rc = virtqueue_read_next_desc(vdev, &desc, desc_cache, max, &i);
+            rc = virtqueue_split_read_next_desc(vdev, &desc, desc_cache, max, &i);
         } while (rc == VIRTQUEUE_READ_DESC_MORE);
 
         if (rc == VIRTQUEUE_READ_DESC_ERROR) {
@@ -730,14 +954,194 @@ done:
         *in_bytes = in_total;
     }
     if (out_bytes) {
-        *out_bytes = out_total;
+        *out_bytes = out_total;
+    }
+    rcu_read_unlock();
+    return;
+
+err:
+    in_total = out_total = 0;
+    goto done;
+}
+
+static int virtqueue_packed_read_next_desc(VirtQueue *vq,
+                                           VRingPackedDesc *desc,
+                                           MemoryRegionCache
+                                           *desc_cache,
+                                           unsigned int max,
+                                           unsigned int *next,
+                                           bool indirect)
+{
+    /* If this descriptor says it doesn't chain, we're done. */
+    if (!indirect && !(desc->flags & VRING_DESC_F_NEXT)) {
+        return VIRTQUEUE_READ_DESC_DONE;
+    }
+
+    ++*next;
+    if (*next == max) {
+        if (indirect) {
+            return VIRTQUEUE_READ_DESC_DONE;
+        } else {
+            (*next) -= vq->vring.num;
+        }
+    }
+
+    vring_packed_desc_read(vq->vdev, desc, desc_cache, *next, false);
+    return VIRTQUEUE_READ_DESC_MORE;
+}
+
+static void virtqueue_packed_get_avail_bytes(VirtQueue *vq,
+                                             unsigned int *in_bytes,
+                                             unsigned int *out_bytes,
+                                             unsigned max_in_bytes,
+                                             unsigned max_out_bytes)
+{
+    VirtIODevice *vdev = vq->vdev;
+    unsigned int max, idx;
+    unsigned int total_bufs, in_total, out_total;
+    MemoryRegionCache *desc_cache;
+    VRingMemoryRegionCaches *caches;
+    MemoryRegionCache indirect_desc_cache = MEMORY_REGION_CACHE_INVALID;
+    int64_t len = 0;
+    VRingPackedDesc desc;
+    bool wrap_counter;
+
+    rcu_read_lock();
+    idx = vq->last_avail_idx;
+    wrap_counter = vq->last_avail_wrap_counter;
+    total_bufs = in_total = out_total = 0;
+
+    max = vq->vring.num;
+    caches = vring_get_region_caches(vq);
+
+    for (;;) {
+        unsigned int num_bufs = total_bufs;
+        unsigned int i = idx;
+        int rc;
+
+        desc_cache = &caches->desc;
+        vring_packed_desc_read(vdev, &desc, desc_cache, idx, true);
+        if (!is_desc_avail(desc.flags, wrap_counter)) {
+            break;
+        }
+
+        if (desc.flags & VRING_DESC_F_INDIRECT) {
+            if (desc.len % sizeof(VRingPackedDesc)) {
+                virtio_error(vdev, "Invalid size for indirect buffer table");
+                goto err;
+            }
+
+            /* If we've got too many, that implies a descriptor loop. */
+            if (num_bufs >= max) {
+                virtio_error(vdev, "Looped descriptor");
+                goto err;
+            }
+
+            /* loop over the indirect descriptor table */
+            len = address_space_cache_init(&indirect_desc_cache,
+                                           vdev->dma_as,
+                                           desc.addr, desc.len, false);
+            desc_cache = &indirect_desc_cache;
+            if (len < desc.len) {
+                virtio_error(vdev, "Cannot map indirect buffer");
+                goto err;
+            }
+
+            max = desc.len / sizeof(VRingPackedDesc);
+            num_bufs = i = 0;
+            vring_packed_desc_read(vdev, &desc, desc_cache, i, false);
+        }
+
+        do {
+            /* If we've got too many, that implies a descriptor loop. */
+            if (++num_bufs > max) {
+                virtio_error(vdev, "Looped descriptor");
+                goto err;
+            }
+
+            if (desc.flags & VRING_DESC_F_WRITE) {
+                in_total += desc.len;
+            } else {
+                out_total += desc.len;
+            }
+            if (in_total >= max_in_bytes && out_total >= max_out_bytes) {
+                goto done;
+            }
+
+            rc = virtqueue_packed_read_next_desc(vq, &desc, desc_cache, max,
+                                                 &i, desc_cache ==
+                                                 &indirect_desc_cache);
+        } while (rc == VIRTQUEUE_READ_DESC_MORE);
+
+        if (desc_cache == &indirect_desc_cache) {
+            address_space_cache_destroy(&indirect_desc_cache);
+            total_bufs++;
+            idx++;
+        } else {
+            idx += num_bufs - total_bufs;
+            total_bufs = num_bufs;
+        }
+
+        if (idx >= vq->vring.num) {
+            idx -= vq->vring.num;
+            wrap_counter ^= 1;
+        }
+    }
+
+    /* Record the index and wrap counter for a kick we want */
+    vq->shadow_avail_idx = idx;
+    vq->shadow_avail_wrap_counter = wrap_counter;
+done:
+    address_space_cache_destroy(&indirect_desc_cache);
+    if (in_bytes) {
+        *in_bytes = in_total;
+    }
+    if (out_bytes) {
+        *out_bytes = out_total;
+    }
+    rcu_read_unlock();
+    return;
+
+err:
+    in_total = out_total = 0;
+    goto done;
+}
+
+void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes,
+                               unsigned int *out_bytes,
+                               unsigned max_in_bytes, unsigned max_out_bytes)
+{
+    uint16_t desc_size;
+    VRingMemoryRegionCaches *caches;
+
+    if (unlikely(!vq->vring.desc)) {
+        goto err;
+    }
+
+    caches = vring_get_region_caches(vq);
+    desc_size = virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED) ?
+                                sizeof(VRingPackedDesc) : sizeof(VRingDesc);
+    if (caches->desc.len < vq->vring.num * desc_size) {
+        virtio_error(vq->vdev, "Cannot map descriptor ring");
+        goto err;
+    }
+
+    if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
+        virtqueue_packed_get_avail_bytes(vq, in_bytes, out_bytes,
+                                         max_in_bytes, max_out_bytes);
+    } else {
+        virtqueue_split_get_avail_bytes(vq, in_bytes, out_bytes,
+                                        max_in_bytes, max_out_bytes);
+    }
+
+    return;
+err:
+    if (in_bytes) {
+        *in_bytes = 0;
+    }
+    if (out_bytes) {
+        *out_bytes = 0;
     }
-    rcu_read_unlock();
-    return;
-
-err:
-    in_total = out_total = 0;
-    goto done;
 }
 
 int virtqueue_avail_bytes(VirtQueue *vq, unsigned int in_bytes,
@@ -864,7 +1268,7 @@ static void *virtqueue_alloc_element(size_t sz, unsigned out_num, unsigned in_nu
     return elem;
 }
 
-void *virtqueue_pop(VirtQueue *vq, size_t sz)
+static void *virtqueue_split_pop(VirtQueue *vq, size_t sz)
 {
     unsigned int i, head, max;
     VRingMemoryRegionCaches *caches;
@@ -879,9 +1283,6 @@ void *virtqueue_pop(VirtQueue *vq, size_t sz)
     VRingDesc desc;
     int rc;
 
-    if (unlikely(vdev->broken)) {
-        return NULL;
-    }
     rcu_read_lock();
     if (virtio_queue_empty_rcu(vq)) {
         goto done;
@@ -917,7 +1318,7 @@ void *virtqueue_pop(VirtQueue *vq, size_t sz)
     }
 
     desc_cache = &caches->desc;
-    vring_desc_read(vdev, &desc, desc_cache, i);
+    vring_split_desc_read(vdev, &desc, desc_cache, i);
     if (desc.flags & VRING_DESC_F_INDIRECT) {
         if (!desc.len || (desc.len % sizeof(VRingDesc))) {
             virtio_error(vdev, "Invalid size for indirect buffer table");
@@ -935,7 +1336,7 @@ void *virtqueue_pop(VirtQueue *vq, size_t sz)
 
         max = desc.len / sizeof(VRingDesc);
         i = 0;
-        vring_desc_read(vdev, &desc, desc_cache, i);
+        vring_split_desc_read(vdev, &desc, desc_cache, i);
     }
 
     /* Collect all the descriptors */
@@ -966,7 +1367,7 @@ void *virtqueue_pop(VirtQueue *vq, size_t sz)
             goto err_undo_map;
         }
 
-        rc = virtqueue_read_next_desc(vdev, &desc, desc_cache, max, &i);
+        rc = virtqueue_split_read_next_desc(vdev, &desc, desc_cache, max, &i);
     } while (rc == VIRTQUEUE_READ_DESC_MORE);
 
     if (rc == VIRTQUEUE_READ_DESC_ERROR) {
@@ -976,6 +1377,7 @@ void *virtqueue_pop(VirtQueue *vq, size_t sz)
     /* Now copy what we have collected and mapped */
     elem = virtqueue_alloc_element(sz, out_num, in_num);
     elem->index = head;
+    elem->ndescs = 1;
     for (i = 0; i < out_num; i++) {
         elem->out_addr[i] = addr[i];
         elem->out_sg[i] = iov[i];
@@ -999,23 +1401,204 @@ err_undo_map:
     goto done;
 }
 
-/* virtqueue_drop_all:
- * @vq: The #VirtQueue
- * Drops all queued buffers and indicates them to the guest
- * as if they are done. Useful when buffers can not be
- * processed but must be returned to the guest.
- */
-unsigned int virtqueue_drop_all(VirtQueue *vq)
+static void *virtqueue_packed_pop(VirtQueue *vq, size_t sz)
+{
+    unsigned int i, max;
+    VRingMemoryRegionCaches *caches;
+    MemoryRegionCache indirect_desc_cache = MEMORY_REGION_CACHE_INVALID;
+    MemoryRegionCache *desc_cache;
+    int64_t len;
+    VirtIODevice *vdev = vq->vdev;
+    VirtQueueElement *elem = NULL;
+    unsigned out_num, in_num, elem_entries;
+    hwaddr addr[VIRTQUEUE_MAX_SIZE];
+    struct iovec iov[VIRTQUEUE_MAX_SIZE];
+    VRingPackedDesc desc;
+    uint16_t id;
+    int rc;
+
+    rcu_read_lock();
+    if (virtio_queue_packed_empty_rcu(vq)) {
+        goto done;
+    }
+
+    /* When we start there are none of either input nor output. */
+    out_num = in_num = elem_entries = 0;
+
+    max = vq->vring.num;
+
+    if (vq->inuse >= vq->vring.num) {
+        virtio_error(vdev, "Virtqueue size exceeded");
+        goto done;
+    }
+
+    i = vq->last_avail_idx;
+
+    caches = vring_get_region_caches(vq);
+    if (caches->desc.len < max * sizeof(VRingDesc)) {
+        virtio_error(vdev, "Cannot map descriptor ring");
+        goto done;
+    }
+
+    desc_cache = &caches->desc;
+    vring_packed_desc_read(vdev, &desc, desc_cache, i, true);
+    id = desc.id;
+    if (desc.flags & VRING_DESC_F_INDIRECT) {
+        if (desc.len % sizeof(VRingPackedDesc)) {
+            virtio_error(vdev, "Invalid size for indirect buffer table");
+            goto done;
+        }
+
+        /* loop over the indirect descriptor table */
+        len = address_space_cache_init(&indirect_desc_cache, vdev->dma_as,
+                                       desc.addr, desc.len, false);
+        desc_cache = &indirect_desc_cache;
+        if (len < desc.len) {
+            virtio_error(vdev, "Cannot map indirect buffer");
+            goto done;
+        }
+
+        max = desc.len / sizeof(VRingPackedDesc);
+        i = 0;
+        vring_packed_desc_read(vdev, &desc, desc_cache, i, false);
+    }
+
+    /* Collect all the descriptors */
+    do {
+        bool map_ok;
+
+        if (desc.flags & VRING_DESC_F_WRITE) {
+            map_ok = virtqueue_map_desc(vdev, &in_num, addr + out_num,
+                                        iov + out_num,
+                                        VIRTQUEUE_MAX_SIZE - out_num, true,
+                                        desc.addr, desc.len);
+        } else {
+            if (in_num) {
+                virtio_error(vdev, "Incorrect order for descriptors");
+                goto err_undo_map;
+            }
+            map_ok = virtqueue_map_desc(vdev, &out_num, addr, iov,
+                                        VIRTQUEUE_MAX_SIZE, false,
+                                        desc.addr, desc.len);
+        }
+        if (!map_ok) {
+            goto err_undo_map;
+        }
+
+        /* If we've got too many, that implies a descriptor loop. */
+        if (++elem_entries > max) {
+            virtio_error(vdev, "Looped descriptor");
+            goto err_undo_map;
+        }
+
+        rc = virtqueue_packed_read_next_desc(vq, &desc, desc_cache, max, &i,
+                                             desc_cache ==
+                                             &indirect_desc_cache);
+    } while (rc == VIRTQUEUE_READ_DESC_MORE);
+
+    /* Now copy what we have collected and mapped */
+    elem = virtqueue_alloc_element(sz, out_num, in_num);
+    for (i = 0; i < out_num; i++) {
+        elem->out_addr[i] = addr[i];
+        elem->out_sg[i] = iov[i];
+    }
+    for (i = 0; i < in_num; i++) {
+        elem->in_addr[i] = addr[out_num + i];
+        elem->in_sg[i] = iov[out_num + i];
+    }
+
+    elem->index = id;
+    elem->ndescs = (desc_cache == &indirect_desc_cache) ? 1 : elem_entries;
+    vq->last_avail_idx += elem->ndescs;
+    vq->inuse += elem->ndescs;
+
+    if (vq->last_avail_idx >= vq->vring.num) {
+        vq->last_avail_idx -= vq->vring.num;
+        vq->last_avail_wrap_counter ^= 1;
+    }
+
+    vq->shadow_avail_idx = vq->last_avail_idx;
+    vq->shadow_avail_wrap_counter = vq->last_avail_wrap_counter;
+
+    trace_virtqueue_pop(vq, elem, elem->in_num, elem->out_num);
+done:
+    address_space_cache_destroy(&indirect_desc_cache);
+    rcu_read_unlock();
+
+    return elem;
+
+err_undo_map:
+    virtqueue_undo_map_desc(out_num, in_num, iov);
+    goto done;
+}
+
+void *virtqueue_pop(VirtQueue *vq, size_t sz)
 {
+    if (unlikely(vq->vdev->broken)) {
+        return NULL;
+    }
+
+    if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
+        return virtqueue_packed_pop(vq, sz);
+    } else {
+        return virtqueue_split_pop(vq, sz);
+    }
+}
+
+static unsigned int virtqueue_packed_drop_all(VirtQueue *vq)
+{
+    VRingMemoryRegionCaches *caches;
+    MemoryRegionCache *desc_cache;
     unsigned int dropped = 0;
     VirtQueueElement elem = {};
     VirtIODevice *vdev = vq->vdev;
-    bool fEventIdx = virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
+    VRingPackedDesc desc;
 
-    if (unlikely(vdev->broken)) {
-        return 0;
+    caches = vring_get_region_caches(vq);
+    desc_cache = &caches->desc;
+
+    virtio_queue_set_notification(vq, 0);
+
+    while (vq->inuse < vq->vring.num) {
+        unsigned int idx = vq->last_avail_idx;
+        /*
+         * works similar to virtqueue_pop but does not map buffers
+         * and does not allocate any memory.
+         */
+        vring_packed_desc_read(vdev, &desc, desc_cache,
+                               vq->last_avail_idx , true);
+        if (!is_desc_avail(desc.flags, vq->last_avail_wrap_counter)) {
+            break;
+        }
+        elem.index = desc.id;
+        elem.ndescs = 1;
+        while (virtqueue_packed_read_next_desc(vq, &desc, desc_cache,
+                                               vq->vring.num, &idx, false)) {
+            ++elem.ndescs;
+        }
+        /*
+         * immediately push the element, nothing to unmap
+         * as both in_num and out_num are set to 0.
+         */
+        virtqueue_push(vq, &elem, 0);
+        dropped++;
+        vq->last_avail_idx += elem.ndescs;
+        if (vq->last_avail_idx >= vq->vring.num) {
+            vq->last_avail_idx -= vq->vring.num;
+            vq->last_avail_wrap_counter ^= 1;
+        }
     }
 
+    return dropped;
+}
+
+static unsigned int virtqueue_split_drop_all(VirtQueue *vq)
+{
+    unsigned int dropped = 0;
+    VirtQueueElement elem = {};
+    VirtIODevice *vdev = vq->vdev;
+    bool fEventIdx = virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
+
     while (!virtio_queue_empty(vq) && vq->inuse < vq->vring.num) {
         /* works similar to virtqueue_pop but does not map buffers
         * and does not allocate any memory */
@@ -1037,6 +1620,27 @@ unsigned int virtqueue_drop_all(VirtQueue *vq)
     return dropped;
 }
 
+/* virtqueue_drop_all:
+ * @vq: The #VirtQueue
+ * Drops all queued buffers and indicates them to the guest
+ * as if they are done. Useful when buffers can not be
+ * processed but must be returned to the guest.
+ */
+unsigned int virtqueue_drop_all(VirtQueue *vq)
+{
+    struct VirtIODevice *vdev = vq->vdev;
+
+    if (unlikely(vdev->broken)) {
+        return 0;
+    }
+
+    if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
+        return virtqueue_packed_drop_all(vq);
+    } else {
+        return virtqueue_split_drop_all(vq);
+    }
+}
+
 /* Reading and writing a structure directly to QEMUFile is *awful*, but
  * it is what QEMU has always done by mistake.  We can change it sooner
  * or later by bumping the version number of the affected vm states.
@@ -1093,11 +1697,16 @@ void *qemu_get_virtqueue_element(VirtIODevice *vdev, QEMUFile *f, size_t sz)
         elem->out_sg[i].iov_len = data.out_sg[i].iov_len;
     }
 
+    if (virtio_host_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
+        qemu_get_be32s(f, &elem->ndescs);
+    }
+
     virtqueue_map(vdev, elem);
     return elem;
 }
 
-void qemu_put_virtqueue_element(QEMUFile *f, VirtQueueElement *elem)
+void qemu_put_virtqueue_element(VirtIODevice *vdev, QEMUFile *f,
+                                VirtQueueElement *elem)
 {
     VirtQueueElementOld data;
     int i;
@@ -1125,6 +1734,11 @@ void qemu_put_virtqueue_element(QEMUFile *f, VirtQueueElement *elem)
         /* Do not save iov_base as above.  */
         data.out_sg[i].iov_len = elem->out_sg[i].iov_len;
     }
+
+    if (virtio_host_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
+        qemu_put_be32s(f, &elem->ndescs);
+    }
+
     qemu_put_buffer(f, (uint8_t *)&data, sizeof(VirtQueueElementOld));
 }
 
@@ -1249,6 +1863,9 @@ void virtio_reset(void *opaque)
         vdev->vq[i].last_avail_idx = 0;
         vdev->vq[i].shadow_avail_idx = 0;
         vdev->vq[i].used_idx = 0;
+        vdev->vq[i].last_avail_wrap_counter = true;
+        vdev->vq[i].shadow_avail_wrap_counter = true;
+        vdev->vq[i].used_wrap_counter = true;
         virtio_queue_set_vector(vdev, i, VIRTIO_NO_VECTOR);
         vdev->vq[i].signalled_used = 0;
         vdev->vq[i].signalled_used_valid = false;
@@ -1639,6 +2256,8 @@ VirtQueue *virtio_add_queue(VirtIODevice *vdev, int queue_size,
     vdev->vq[i].vring.align = VIRTIO_PCI_VRING_ALIGN;
     vdev->vq[i].handle_output = handle_output;
     vdev->vq[i].handle_aio_output = NULL;
+    vdev->vq[i].used_elems = g_malloc0(sizeof(VirtQueueElement) *
+                                       queue_size);
 
     return &vdev->vq[i];
 }
@@ -1653,6 +2272,7 @@ void virtio_del_queue(VirtIODevice *vdev, int n)
     vdev->vq[n].vring.num_default = 0;
     vdev->vq[n].handle_output = NULL;
     vdev->vq[n].handle_aio_output = NULL;
+    g_free(vdev->vq[n].used_elems);
 }
 
 static void virtio_set_isr(VirtIODevice *vdev, int value)
@@ -1780,6 +2400,13 @@ static bool virtio_virtqueue_needed(void *opaque)
     return virtio_host_has_feature(vdev, VIRTIO_F_VERSION_1);
 }
 
+static bool virtio_packed_virtqueue_needed(void *opaque)
+{
+    VirtIODevice *vdev = opaque;
+
+    return virtio_host_has_feature(vdev, VIRTIO_F_RING_PACKED);
+}
+
 static bool virtio_ringsize_needed(void *opaque)
 {
     VirtIODevice *vdev = opaque;
@@ -1828,6 +2455,20 @@ static const VMStateDescription vmstate_virtqueue = {
     }
 };
 
+static const VMStateDescription vmstate_packed_virtqueue = {
+    .name = "packed_virtqueue_state",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT16(last_avail_idx, struct VirtQueue),
+        VMSTATE_BOOL(last_avail_wrap_counter, struct VirtQueue),
+        VMSTATE_UINT16(used_idx, struct VirtQueue),
+        VMSTATE_BOOL(used_wrap_counter, struct VirtQueue),
+        VMSTATE_UINT32(inuse, struct VirtQueue),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static const VMStateDescription vmstate_virtio_virtqueues = {
     .name = "virtio/virtqueues",
     .version_id = 1,
@@ -1840,6 +2481,18 @@ static const VMStateDescription vmstate_virtio_virtqueues = {
     }
 };
 
+static const VMStateDescription vmstate_virtio_packed_virtqueues = {
+    .name = "virtio/packed_virtqueues",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = &virtio_packed_virtqueue_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_STRUCT_VARRAY_POINTER_KNOWN(vq, struct VirtIODevice,
+                      VIRTIO_QUEUE_MAX, 0, vmstate_packed_virtqueue, VirtQueue),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static const VMStateDescription vmstate_ringsize = {
     .name = "ringsize_state",
     .version_id = 1,
@@ -1972,6 +2625,7 @@ static const VMStateDescription vmstate_virtio = {
         &vmstate_virtio_broken,
         &vmstate_virtio_extra_state,
         &vmstate_virtio_started,
+        &vmstate_virtio_packed_virtqueues,
         NULL
     }
 };
@@ -2271,6 +2925,13 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f, int version_id)
                 virtio_queue_update_rings(vdev, i);
             }
 
+            if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
+                vdev->vq[i].shadow_avail_idx = vdev->vq[i].last_avail_idx;
+                vdev->vq[i].shadow_avail_wrap_counter =
+                                        vdev->vq[i].last_avail_wrap_counter;
+                continue;
+            }
+
             nheads = vring_avail_idx(&vdev->vq[i]) - vdev->vq[i].last_avail_idx;
             /* Check it isn't doing strange things with descriptor numbers. */
             if (nheads > vdev->vq[i].vring.num) {
@@ -2414,6 +3075,10 @@ hwaddr virtio_queue_get_avail_size(VirtIODevice *vdev, int n)
 {
     int s;
 
+    if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
+        return sizeof(struct VRingPackedDescEvent);
+    }
+
     s = virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
     return offsetof(VRingAvail, ring) +
         sizeof(uint16_t) * vdev->vq[n].vring.num + s;
@@ -2423,23 +3088,83 @@ hwaddr virtio_queue_get_used_size(VirtIODevice *vdev, int n)
 {
     int s;
 
+    if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
+        return sizeof(struct VRingPackedDescEvent);
+    }
+
     s = virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
     return offsetof(VRingUsed, ring) +
         sizeof(VRingUsedElem) * vdev->vq[n].vring.num + s;
 }
 
-uint16_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n)
+static unsigned int virtio_queue_packed_get_last_avail_idx(VirtIODevice *vdev,
+                                                           int n)
+{
+    unsigned int avail, used;
+
+    avail = vdev->vq[n].last_avail_idx;
+    avail |= ((uint16_t)vdev->vq[n].last_avail_wrap_counter) << 15;
+
+    used = vdev->vq[n].used_idx;
+    used |= ((uint16_t)vdev->vq[n].used_wrap_counter) << 15;
+
+    return avail | used << 16;
+}
+
+static uint16_t virtio_queue_split_get_last_avail_idx(VirtIODevice *vdev,
+                                                      int n)
 {
     return vdev->vq[n].last_avail_idx;
 }
 
-void virtio_queue_set_last_avail_idx(VirtIODevice *vdev, int n, uint16_t idx)
+unsigned int virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n)
 {
-    vdev->vq[n].last_avail_idx = idx;
-    vdev->vq[n].shadow_avail_idx = idx;
+    if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
+        return virtio_queue_packed_get_last_avail_idx(vdev, n);
+    } else {
+        return virtio_queue_split_get_last_avail_idx(vdev, n);
+    }
 }
 
-void virtio_queue_restore_last_avail_idx(VirtIODevice *vdev, int n)
+static void virtio_queue_packed_set_last_avail_idx(VirtIODevice *vdev,
+                                                   int n, unsigned int idx)
+{
+    struct VirtQueue *vq = &vdev->vq[n];
+
+    vq->last_avail_idx = vq->shadow_avail_idx = idx & 0x7fff;
+    vq->last_avail_wrap_counter =
+        vq->shadow_avail_wrap_counter = !!(idx & 0x8000);
+    idx >>= 16;
+    vq->used_idx = idx & 0x7ffff;
+    vq->used_wrap_counter = !!(idx & 0x8000);
+}
+
+static void virtio_queue_split_set_last_avail_idx(VirtIODevice *vdev,
+                                                  int n, unsigned int idx)
+{
+        vdev->vq[n].last_avail_idx = idx;
+        vdev->vq[n].shadow_avail_idx = idx;
+}
+
+void virtio_queue_set_last_avail_idx(VirtIODevice *vdev, int n,
+                                     unsigned int idx)
+{
+    if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
+        virtio_queue_packed_set_last_avail_idx(vdev, n, idx);
+    } else {
+        virtio_queue_split_set_last_avail_idx(vdev, n, idx);
+    }
+}
+
+static void virtio_queue_packed_restore_last_avail_idx(VirtIODevice *vdev,
+                                                       int n)
+{
+    /* We don't have a reference like avail idx in shared memory */
+    return;
+}
+
+static void virtio_queue_split_restore_last_avail_idx(VirtIODevice *vdev,
+                                                      int n)
 {
     rcu_read_lock();
     if (vdev->vq[n].vring.desc) {
@@ -2449,7 +3174,22 @@ void virtio_queue_restore_last_avail_idx(VirtIODevice *vdev, int n)
     rcu_read_unlock();
 }
 
-void virtio_queue_update_used_idx(VirtIODevice *vdev, int n)
+void virtio_queue_restore_last_avail_idx(VirtIODevice *vdev, int n)
+{
+    if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
+        virtio_queue_packed_restore_last_avail_idx(vdev, n);
+    } else {
+        virtio_queue_split_restore_last_avail_idx(vdev, n);
+    }
+}
+
+static void virtio_queue_packed_update_used_idx(VirtIODevice *vdev, int n)
+{
+    /* used idx was updated through set_last_avail_idx() */
+    return;
+}
+
+static void virtio_split_packed_update_used_idx(VirtIODevice *vdev, int n)
 {
     rcu_read_lock();
     if (vdev->vq[n].vring.desc) {
@@ -2458,6 +3198,15 @@ void virtio_queue_update_used_idx(VirtIODevice *vdev, int n)
     rcu_read_unlock();
 }
 
+void virtio_queue_update_used_idx(VirtIODevice *vdev, int n)
+{
+    if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
+        return virtio_queue_packed_update_used_idx(vdev, n);
+    } else {
+        return virtio_split_packed_update_used_idx(vdev, n);
+    }
+}
+
 void virtio_queue_invalidate_signalled_used(VirtIODevice *vdev, int n)
 {
     vdev->vq[n].signalled_used_valid = false;
diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index 48e8d04ff6..d123d5b181 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -59,6 +59,8 @@ typedef struct VirtQueue VirtQueue;
 typedef struct VirtQueueElement
 {
     unsigned int index;
+    unsigned int len;
+    unsigned int ndescs;
     unsigned int out_num;
     unsigned int in_num;
     hwaddr *in_addr;
@@ -196,7 +198,8 @@ void virtqueue_map(VirtIODevice *vdev, VirtQueueElement *elem);
 void *virtqueue_pop(VirtQueue *vq, size_t sz);
 unsigned int virtqueue_drop_all(VirtQueue *vq);
 void *qemu_get_virtqueue_element(VirtIODevice *vdev, QEMUFile *f, size_t sz);
-void qemu_put_virtqueue_element(QEMUFile *f, VirtQueueElement *elem);
+void qemu_put_virtqueue_element(VirtIODevice *vdev, QEMUFile *f,
+                                VirtQueueElement *elem);
 int virtqueue_avail_bytes(VirtQueue *vq, unsigned int in_bytes,
                           unsigned int out_bytes);
 void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes,
@@ -291,8 +294,9 @@ hwaddr virtio_queue_get_used_addr(VirtIODevice *vdev, int n);
 hwaddr virtio_queue_get_desc_size(VirtIODevice *vdev, int n);
 hwaddr virtio_queue_get_avail_size(VirtIODevice *vdev, int n);
 hwaddr virtio_queue_get_used_size(VirtIODevice *vdev, int n);
-uint16_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n);
-void virtio_queue_set_last_avail_idx(VirtIODevice *vdev, int n, uint16_t idx);
+unsigned int virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n);
+void virtio_queue_set_last_avail_idx(VirtIODevice *vdev, int n,
+                                     unsigned int idx);
 void virtio_queue_restore_last_avail_idx(VirtIODevice *vdev, int n);
 void virtio_queue_invalidate_signalled_used(VirtIODevice *vdev, int n);
 void virtio_queue_update_used_idx(VirtIODevice *vdev, int n);
-- 
2.16.5

[PATCH v7 6/8] virtio: event suppression support for packed ring

[Eugenio Pérez]

From: Jason Wang <jasowang@redhat.com>

This patch implements event suppression through device/driver
area. Please refer virtio specification for more information.

Signed-off-by: Wei Xu <wexu@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 hw/virtio/virtio.c | 142 +++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 133 insertions(+), 9 deletions(-)

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index a694b4ab50..828c27de1f 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -240,6 +240,44 @@ static void vring_split_desc_read(VirtIODevice *vdev, VRingDesc *desc,
     virtio_tswap16s(vdev, &desc->next);
 }
 
+static void vring_packed_event_read(VirtIODevice *vdev,
+                                    MemoryRegionCache *cache,
+                                    VRingPackedDescEvent *e)
+{
+    hwaddr off_off = offsetof(VRingPackedDescEvent, off_wrap);
+    hwaddr off_flags = offsetof(VRingPackedDescEvent, flags);
+
+    address_space_read_cached(cache, off_flags, &e->flags,
+                              sizeof(e->flags));
+    /* Make sure flags is seen before off_wrap */
+    smp_rmb();
+    address_space_read_cached(cache, off_off, &e->off_wrap,
+                              sizeof(e->off_wrap));
+    virtio_tswap16s(vdev, &e->off_wrap);
+    virtio_tswap16s(vdev, &e->flags);
+}
+
+static void vring_packed_off_wrap_write(VirtIODevice *vdev,
+                                        MemoryRegionCache *cache,
+                                        uint16_t off_wrap)
+{
+    hwaddr off = offsetof(VRingPackedDescEvent, off_wrap);
+
+    virtio_tswap16s(vdev, &off_wrap);
+    address_space_write_cached(cache, off, &off_wrap, sizeof(off_wrap));
+    address_space_cache_invalidate(cache, off, sizeof(off_wrap));
+}
+
+static void vring_packed_flags_write(VirtIODevice *vdev,
+                                     MemoryRegionCache *cache, uint16_t flags)
+{
+    hwaddr off = offsetof(VRingPackedDescEvent, flags);
+
+    virtio_tswap16s(vdev, &flags);
+    address_space_write_cached(cache, off, &flags, sizeof(flags));
+    address_space_cache_invalidate(cache, off, sizeof(flags));
+}
+
 /* Called within rcu_read_lock().  */
 static VRingMemoryRegionCaches *vring_get_region_caches(struct VirtQueue *vq)
 {
@@ -347,14 +385,8 @@ static inline void vring_set_avail_event(VirtQueue *vq, uint16_t val)
     address_space_cache_invalidate(&caches->used, pa, sizeof(val));
 }
 
-void virtio_queue_set_notification(VirtQueue *vq, int enable)
+static void virtio_queue_split_set_notification(VirtQueue *vq, int enable)
 {
-    vq->notification = enable;
-
-    if (!vq->vring.desc) {
-        return;
-    }
-
     rcu_read_lock();
     if (virtio_vdev_has_feature(vq->vdev, VIRTIO_RING_F_EVENT_IDX)) {
         vring_set_avail_event(vq, vring_avail_idx(vq));
@@ -370,6 +402,51 @@ void virtio_queue_set_notification(VirtQueue *vq, int enable)
     rcu_read_unlock();
 }
 
+static void virtio_queue_packed_set_notification(VirtQueue *vq, int enable)
+{
+    uint16_t off_wrap;
+    VRingPackedDescEvent e;
+    VRingMemoryRegionCaches *caches;
+
+    rcu_read_lock();
+    caches  = vring_get_region_caches(vq);
+    vring_packed_event_read(vq->vdev, &caches->used, &e);
+
+    if (!enable) {
+        e.flags = VRING_PACKED_EVENT_FLAG_DISABLE;
+    } else if (virtio_vdev_has_feature(vq->vdev, VIRTIO_RING_F_EVENT_IDX)) {
+        off_wrap = vq->shadow_avail_idx | vq->shadow_avail_wrap_counter << 15;
+        vring_packed_off_wrap_write(vq->vdev, &caches->used, off_wrap);
+        /* Make sure off_wrap is wrote before flags */
+        smp_wmb();
+        e.flags = VRING_PACKED_EVENT_FLAG_DESC;
+    } else {
+        e.flags = VRING_PACKED_EVENT_FLAG_ENABLE;
+    }
+
+    vring_packed_flags_write(vq->vdev, &caches->used, e.flags);
+    if (enable) {
+        /* Expose avail event/used flags before caller checks the avail idx. */
+        smp_mb();
+    }
+    rcu_read_unlock();
+}
+
+void virtio_queue_set_notification(VirtQueue *vq, int enable)
+{
+    vq->notification = enable;
+
+    if (!vq->vring.desc) {
+        return;
+    }
+
+    if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
+        virtio_queue_packed_set_notification(vq, enable);
+    } else {
+        virtio_queue_split_set_notification(vq, enable);
+    }
+}
+
 int virtio_queue_ready(VirtQueue *vq)
 {
     return vq->vring.avail != 0;
@@ -2287,8 +2364,7 @@ static void virtio_set_isr(VirtIODevice *vdev, int value)
     }
 }
 
-/* Called within rcu_read_lock().  */
-static bool virtio_should_notify(VirtIODevice *vdev, VirtQueue *vq)
+static bool virtio_split_should_notify(VirtIODevice *vdev, VirtQueue *vq)
 {
     uint16_t old, new;
     bool v;
@@ -2311,6 +2387,54 @@ static bool virtio_should_notify(VirtIODevice *vdev, VirtQueue *vq)
     return !v || vring_need_event(vring_get_used_event(vq), new, old);
 }
 
+static bool vring_packed_need_event(VirtQueue *vq, bool wrap,
+                                    uint16_t off_wrap, uint16_t new,
+                                    uint16_t old)
+{
+    int off = off_wrap & ~(1 << 15);
+
+    if (wrap != off_wrap >> 15) {
+        off -= vq->vring.num;
+    }
+
+    return vring_need_event(off, new, old);
+}
+
+static bool virtio_packed_should_notify(VirtIODevice *vdev, VirtQueue *vq)
+{
+    VRingPackedDescEvent e;
+    uint16_t old, new;
+    bool v;
+    VRingMemoryRegionCaches *caches;
+
+    caches = vring_get_region_caches(vq);
+    vring_packed_event_read(vdev, &caches->avail, &e);
+
+    old = vq->signalled_used;
+    new = vq->signalled_used = vq->used_idx;
+    v = vq->signalled_used_valid;
+    vq->signalled_used_valid = true;
+
+    if (e.flags == VRING_PACKED_EVENT_FLAG_DISABLE) {
+        return false;
+    } else if (e.flags == VRING_PACKED_EVENT_FLAG_ENABLE) {
+        return true;
+    }
+
+    return !v || vring_packed_need_event(vq, vq->used_wrap_counter,
+                                         e.off_wrap, new, old);
+}
+
+/* Called within rcu_read_lock().  */
+static bool virtio_should_notify(VirtIODevice *vdev, VirtQueue *vq)
+{
+    if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
+        return virtio_packed_should_notify(vdev, vq);
+    } else {
+        return virtio_split_should_notify(vdev, vq);
+    }
+}
+
 void virtio_notify_irqfd(VirtIODevice *vdev, VirtQueue *vq)
 {
     bool should_notify;
-- 
2.16.5

[PATCH v7 7/8] vhost_net: enable packed ring support

[Eugenio Pérez]

From: Jason Wang <jasowang@redhat.com>

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Reviewed-by: Jens Freimann <jfreimann@redhat.com>
---
 hw/net/vhost_net.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
index e975700f95..6b82803fa7 100644
--- a/hw/net/vhost_net.c
+++ b/hw/net/vhost_net.c
@@ -49,6 +49,7 @@ static const int kernel_feature_bits[] = {
     VIRTIO_F_VERSION_1,
     VIRTIO_NET_F_MTU,
     VIRTIO_F_IOMMU_PLATFORM,
+    VIRTIO_F_RING_PACKED,
     VHOST_INVALID_FEATURE_BIT
 };
 
@@ -74,6 +75,7 @@ static const int user_feature_bits[] = {
     VIRTIO_NET_F_MRG_RXBUF,
     VIRTIO_NET_F_MTU,
     VIRTIO_F_IOMMU_PLATFORM,
+    VIRTIO_F_RING_PACKED,
 
     /* This bit implies RARP isn't sent by QEMU out of band */
     VIRTIO_NET_F_GUEST_ANNOUNCE,
-- 
2.16.5

[PATCH v7 8/8] virtio: add property to enable packed virtqueue

[Eugenio Pérez]

From: Jason Wang <jasowang@redhat.com>

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Reviewed-by: Jens Freimann <jfreimann@redhat.com>
---
 include/hw/virtio/virtio.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index d123d5b181..40ddeafadb 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -285,7 +285,9 @@ typedef struct VirtIORNGConf VirtIORNGConf;
     DEFINE_PROP_BIT64("any_layout", _state, _field, \
                       VIRTIO_F_ANY_LAYOUT, true), \
     DEFINE_PROP_BIT64("iommu_platform", _state, _field, \
-                      VIRTIO_F_IOMMU_PLATFORM, false)
+                      VIRTIO_F_IOMMU_PLATFORM, false), \
+    DEFINE_PROP_BIT64("packed", _state, _field, \
+                      VIRTIO_F_RING_PACKED, false)
 
 hwaddr virtio_queue_get_desc_addr(VirtIODevice *vdev, int n);
 bool virtio_queue_enabled(VirtIODevice *vdev, int n);
-- 
2.16.5

Re: [PATCH v7 0/8] Packed virtqueue for virtio

[Michael S. Tsirkin]

On Fri, Oct 25, 2019 at 10:35:19AM +0200, Eugenio Pérez wrote:
> Hi:
> 
> This is an updated version of packed virtqueue support based on Wei and Jason's
> V6, mainly solving the clang leak detector error CI gave.


Looks good, I will queue this up.

It would be nice to add libqos based tests on top,
based on Stefan's work.


> Please review.
> 
> Changes from V6:
> - Commit reorder: Squash bugfix and sepparate big changes into smaller commits.
> 
> Changes from V5:
> - Fix qemu's CI asan error.
> - Move/copy rcu comments.
> - Merge duplicated vdev->broken check between split and packet version.
> 
> Eugenio Pérez (2):
>   virtio: Free blk virqueues at unrealize()
>   virtio: Free rnd virqueue at unrealize()
> 
> Jason Wang (4):
>   virtio: basic packed virtqueue support
>   virtio: event suppression support for packed ring
>   vhost_net: enable packed ring support
>   virtio: add property to enable packed virtqueue
> 
> Wei Xu (2):
>   virtio: basic structure for packed ring
>   virtio: device/driver area size calculation refactor for split ring
> 
>  hw/block/virtio-blk.c       |    7 +-
>  hw/char/virtio-serial-bus.c |    2 +-
>  hw/net/vhost_net.c          |    2 +
>  hw/scsi/virtio-scsi.c       |    3 +-
>  hw/virtio/virtio-rng.c      |    1 +
>  hw/virtio/virtio.c          | 1154 ++++++++++++++++++++++++++++++++++++++-----
>  include/hw/virtio/virtio.h  |   14 +-
>  7 files changed, 1045 insertions(+), 138 deletions(-)
> 
> -- 
> 2.16.5

Re: [PATCH v7 0/8] Packed virtqueue for virtio

[Stefan Hajnoczi]

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On Fri, Oct 25, 2019 at 07:34:03AM -0400, Michael S. Tsirkin wrote:
> On Fri, Oct 25, 2019 at 10:35:19AM +0200, Eugenio Pérez wrote:
> > Hi:
> > 
> > This is an updated version of packed virtqueue support based on Wei and Jason's
> > V6, mainly solving the clang leak detector error CI gave.
> 
> 
> Looks good, I will queue this up.
> 
> It would be nice to add libqos based tests on top,
> based on Stefan's work.

Packed virtqueue support in libqos would be nice now that we have VIRTIO
1.0 support.  I think it could be added nicely now.

Writing a low-level virtqueue layout test is also possible if you want
to test QEMU's packed virtqueue code.  For example, a test case could
trigger error code paths by creating invalid rings/descriptors.

Stefan

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Re: [PATCH v7 0/8] Packed virtqueue for virtio

[Eugenio Perez Martin]

Hi Michael.

Totally agree with you. I investigated that for a short time but in
the end I tested manually with the coverage instrumentation, trying to
exercise the same "code" as current tests touches in split virtqueues.

I will automate at least these paths.

Thanks!


On Fri, Oct 25, 2019 at 1:35 PM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Fri, Oct 25, 2019 at 10:35:19AM +0200, Eugenio Pérez wrote:
> > Hi:
> >
> > This is an updated version of packed virtqueue support based on Wei and Jason's
> > V6, mainly solving the clang leak detector error CI gave.
>
>
> Looks good, I will queue this up.
>
> It would be nice to add libqos based tests on top,
> based on Stefan's work.
>
>
> > Please review.
> >
> > Changes from V6:
> > - Commit reorder: Squash bugfix and sepparate big changes into smaller commits.
> >
> > Changes from V5:
> > - Fix qemu's CI asan error.
> > - Move/copy rcu comments.
> > - Merge duplicated vdev->broken check between split and packet version.
> >
> > Eugenio Pérez (2):
> >   virtio: Free blk virqueues at unrealize()
> >   virtio: Free rnd virqueue at unrealize()
> >
> > Jason Wang (4):
> >   virtio: basic packed virtqueue support
> >   virtio: event suppression support for packed ring
> >   vhost_net: enable packed ring support
> >   virtio: add property to enable packed virtqueue
> >
> > Wei Xu (2):
> >   virtio: basic structure for packed ring
> >   virtio: device/driver area size calculation refactor for split ring
> >
> >  hw/block/virtio-blk.c       |    7 +-
> >  hw/char/virtio-serial-bus.c |    2 +-
> >  hw/net/vhost_net.c          |    2 +
> >  hw/scsi/virtio-scsi.c       |    3 +-
> >  hw/virtio/virtio-rng.c      |    1 +
> >  hw/virtio/virtio.c          | 1154 ++++++++++++++++++++++++++++++++++++++-----
> >  include/hw/virtio/virtio.h  |   14 +-
> >  7 files changed, 1045 insertions(+), 138 deletions(-)
> >
> > --
> > 2.16.5