This patch implements in order support for both split virtqueue and
packed virtqueue. Perfomance could be gained for the device where the
memory access could be expensive (e.g vhost-net or a real PCI device):

Benchmark with KVM guest:

Vhost-net on the host: (pktgen + XDP_DROP):

         in_order=off | in_order=on | +%
    TX:  5.20Mpps     | 6.20Mpps    | +19%
    RX:  3.47Mpps     | 3.61Mpps    | + 4%

Vhost-user(testpmd) on the host: (pktgen/XDP_DROP):

For split virtqueue:

         in_order=off | in_order=on | +%
    TX:  5.60Mpps     | 5.60Mpps    | +0.0%
    RX:  9.16Mpps     | 9.61Mpps    | +4.9%

For packed virtqueue:

         in_order=off | in_order=on | +%
    TX:  5.60Mpps     | 5.70Mpps    | +1.7%
    RX:  10.6Mpps     | 10.8Mpps    | +1.8%

Benchmark also shows no performance impact for in_order=off for queue
size with 256 and 1024.

Signed-off-by: Jason Wang <jasow...@redhat.com>
Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
---
Changes since V4:
- Fix build error when DEBUG is enabled
- Fix function duplications
- Remove unnecessary new lines
---
drivers/virtio/virtio_ring.c | 421 +++++++++++++++++++++++++++++++++--
 1 file changed, 401 insertions(+), 20 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index e675d8305dbf..c6558e271f97 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -70,11 +70,14 @@
 enum vq_layout {
        SPLIT = 0,
        PACKED,
+       SPLIT_IN_ORDER,
+       PACKED_IN_ORDER,
        VQ_TYPE_MAX,
 };
 
 struct vring_desc_state_split {
        void *data;                     /* Data for callback. */
+       u32 total_len;                  /* Buffer Length */
 
        /* Indirect desc table and extra table, if any. These two will be
         * allocated together. So we won't stress more to the memory allocator.
@@ -84,6 +87,7 @@ struct vring_desc_state_split {
 
 struct vring_desc_state_packed {
        void *data;                     /* Data for callback. */
+       u32 total_len;                  /* Buffer Length */
 
        /* Indirect desc table and extra table, if any. These two will be
         * allocated together. So we won't stress more to the memory allocator.
@@ -206,6 +210,17 @@ struct vring_virtqueue {
 
        /* Head of free buffer list. */
        unsigned int free_head;
+
+       /*
+        * With IN_ORDER, devices write a single used ring entry with
+        * the id corresponding to the head entry of the descriptor chain
+        * describing the last buffer in the batch
+        */
+       struct used_entry {
+               u32 id;
+               u32 len;
+       } batch_last;
+
        /* Number we've added since last sync. */
        unsigned int num_added;
 
@@ -259,7 +274,12 @@ static void vring_free(struct virtqueue *_vq);
 
 static inline bool virtqueue_is_packed(const struct vring_virtqueue *vq)
 {
-       return vq->layout == PACKED;
+       return vq->layout == PACKED || vq->layout == PACKED_IN_ORDER;
+}
+
+static inline bool virtqueue_is_in_order(const struct vring_virtqueue *vq)
+{
+       return vq->layout == SPLIT_IN_ORDER || vq->layout == PACKED_IN_ORDER;
 }
 
 static bool virtqueue_use_indirect(const struct vring_virtqueue *vq,
@@ -571,6 +591,8 @@ static inline int virtqueue_add_split(struct 
vring_virtqueue *vq,
        struct scatterlist *sg;
        struct vring_desc *desc;
        unsigned int i, n, avail, descs_used, err_idx, c = 0;
+       /* Total length for in-order */
+       unsigned int total_len = 0;
        int head;
        bool indirect;
 
@@ -642,6 +664,7 @@ static inline int virtqueue_add_split(struct 
vring_virtqueue *vq,
                                                     ++c == total_sg ?
                                                     0 : VRING_DESC_F_NEXT,
                                                     premapped);
+                       total_len += len;
                }
        }
        for (; n < (out_sgs + in_sgs); n++) {
@@ -659,6 +682,7 @@ static inline int virtqueue_add_split(struct 
vring_virtqueue *vq,
                                i, addr, len,
                                (++c == total_sg ? 0 : VRING_DESC_F_NEXT) |
                                VRING_DESC_F_WRITE, premapped);
+                       total_len += len;
                }
        }
 
@@ -681,7 +705,12 @@ static inline int virtqueue_add_split(struct 
vring_virtqueue *vq,
        vq->vq.num_free -= descs_used;
 
        /* Update free pointer */
-       if (indirect)
+       if (virtqueue_is_in_order(vq)) {
+               vq->free_head += descs_used;
+               if (vq->free_head >= vq->split.vring.num)
+                       vq->free_head -= vq->split.vring.num;
+               vq->split.desc_state[head].total_len = total_len;;
+       } else if (indirect)
                vq->free_head = vq->split.desc_extra[head].next;
        else
                vq->free_head = i;
@@ -854,6 +883,14 @@ static bool more_used_split(const struct vring_virtqueue 
*vq)
        return virtqueue_poll_split(vq, vq->last_used_idx);
 }
 
+static bool more_used_split_in_order(const struct vring_virtqueue *vq)
+{
+       if (vq->batch_last.id != vq->packed.vring.num)
+               return true;
+
+       return virtqueue_poll_split(vq, vq->last_used_idx);
+}
+
 static void *virtqueue_get_buf_ctx_split(struct vring_virtqueue *vq,
                                         unsigned int *len,
                                         void **ctx)
@@ -911,6 +948,73 @@ static void *virtqueue_get_buf_ctx_split(struct 
vring_virtqueue *vq,
        return ret;
 }
 
+static void *virtqueue_get_buf_ctx_split_in_order(struct vring_virtqueue *vq,
+                                                 unsigned int *len,
+                                                 void **ctx)
+{
+       void *ret;
+       unsigned int num = vq->split.vring.num;
+       u16 last_used;
+
+       START_USE(vq);
+
+       if (unlikely(vq->broken)) {
+               END_USE(vq);
+               return NULL;
+       }
+
+       last_used = (vq->last_used_idx & (vq->split.vring.num - 1));
+
+       if (vq->batch_last.id == num) {
+               if (!more_used_split(vq)) {
+                       pr_debug("No more buffers in queue\n");
+                       END_USE(vq);
+                       return NULL;
+               }
+
+               /* Only get used array entries after they have been
+                * exposed by host. */
+               virtio_rmb(vq->weak_barriers);
+               vq->batch_last.id = virtio32_to_cpu(vq->vq.vdev,
+                                   vq->split.vring.used->ring[last_used].id);
+               vq->batch_last.len = virtio32_to_cpu(vq->vq.vdev,
+                                    vq->split.vring.used->ring[last_used].len);
+       }
+
+       if (vq->batch_last.id == last_used) {
+               vq->batch_last.id = num;
+               *len = vq->batch_last.len;
+       } else
+               *len = vq->split.desc_state[last_used].total_len;
+
+       if (unlikely(last_used >= num)) {
+               BAD_RING(vq, "id %u out of range\n", last_used);
+               return NULL;
+       }
+       if (unlikely(!vq->split.desc_state[last_used].data)) {
+               BAD_RING(vq, "id %u is not a head!\n", last_used);
+               return NULL;
+       }
+
+       /* detach_buf_split clears data, so grab it now. */
+       ret = vq->split.desc_state[last_used].data;
+       detach_buf_split_in_order(vq, last_used, ctx);
+
+       vq->last_used_idx++;
+       /* If we expect an interrupt for the next entry, tell host
+        * by writing event index and flush out the write before
+        * the read in the next get_buf call. */
+       if (!(vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT))
+               virtio_store_mb(vq->weak_barriers,
+                               &vring_used_event(&vq->split.vring),
+                               cpu_to_virtio16(vq->vq.vdev, 
vq->last_used_idx));
+
+       LAST_ADD_TIME_INVALID(vq);
+
+       END_USE(vq);
+       return ret;
+}
+
 static void virtqueue_disable_cb_split(struct vring_virtqueue *vq)
 {
        if (!(vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) {
@@ -1004,7 +1108,10 @@ static void *virtqueue_detach_unused_buf_split(struct 
vring_virtqueue *vq)
                        continue;
                /* detach_buf_split clears data, so grab it now. */
                buf = vq->split.desc_state[i].data;
-               detach_buf_split(vq, i, NULL);
+               if (virtqueue_is_in_order(vq))
+                       detach_buf_split_in_order(vq, i, NULL);
+               else
+                       detach_buf_split(vq, i, NULL);
                vq->split.avail_idx_shadow--;
                vq->split.vring.avail->idx = cpu_to_virtio16(vq->vq.vdev,
                                vq->split.avail_idx_shadow);
@@ -1067,6 +1174,7 @@ static void virtqueue_vring_attach_split(struct 
vring_virtqueue *vq,
 
        /* Put everything in free lists. */
        vq->free_head = 0;
+       vq->batch_last.id = vq->split.vring.num;
 }
 
 static int vring_alloc_state_extra_split(struct vring_virtqueue_split 
*vring_split)
@@ -1177,7 +1285,6 @@ static struct virtqueue 
*__vring_new_virtqueue_split(unsigned int index,
        if (!vq)
                return NULL;
 
-       vq->layout = SPLIT;
        vq->vq.callback = callback;
        vq->vq.vdev = vdev;
        vq->vq.name = name;
@@ -1197,6 +1304,8 @@ static struct virtqueue 
*__vring_new_virtqueue_split(unsigned int index,
        vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) &&
                !context;
        vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
+       vq->layout = virtio_has_feature(vdev, VIRTIO_F_IN_ORDER) ?
+                    SPLIT_IN_ORDER : SPLIT;
 
        if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM))
                vq->weak_barriers = false;
@@ -1360,13 +1469,14 @@ static int virtqueue_add_indirect_packed(struct 
vring_virtqueue *vq,
                                         unsigned int in_sgs,
                                         void *data,
                                         bool premapped,
-                                        gfp_t gfp)
+                                        gfp_t gfp,
+                                        u16 id)
 {
        struct vring_desc_extra *extra;
        struct vring_packed_desc *desc;
        struct scatterlist *sg;
-       unsigned int i, n, err_idx, len;
-       u16 head, id;
+       unsigned int i, n, err_idx, len, total_len = 0;
+       u16 head;
        dma_addr_t addr;
 
        head = vq->packed.next_avail_idx;
@@ -1384,8 +1494,6 @@ static int virtqueue_add_indirect_packed(struct 
vring_virtqueue *vq,
        }
 
        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)) {
@@ -1405,6 +1513,7 @@ static int virtqueue_add_indirect_packed(struct 
vring_virtqueue *vq,
                                extra[i].flags = n < out_sgs ?  0 : 
VRING_DESC_F_WRITE;
                        }
 
+                       total_len += len;
                        i++;
                }
        }
@@ -1458,6 +1567,7 @@ static int virtqueue_add_indirect_packed(struct 
vring_virtqueue *vq,
        vq->packed.desc_state[id].data = data;
        vq->packed.desc_state[id].indir_desc = desc;
        vq->packed.desc_state[id].last = id;
+       vq->packed.desc_state[id].total_len = total_len;
 
        vq->num_added += 1;
 
@@ -1510,8 +1620,11 @@ static inline int virtqueue_add_packed(struct 
vring_virtqueue *vq,
        BUG_ON(total_sg == 0);
 
        if (virtqueue_use_indirect(vq, total_sg)) {
+               id = vq->free_head;
+               BUG_ON(id == vq->packed.vring.num);
                err = virtqueue_add_indirect_packed(vq, sgs, total_sg, out_sgs,
-                                                   in_sgs, data, premapped, 
gfp);
+                                                   in_sgs, data, premapped,
+                                                   gfp, id);
                if (err != -ENOMEM) {
                        END_USE(vq);
                        return err;
@@ -1632,6 +1745,152 @@ static inline int virtqueue_add_packed(struct 
vring_virtqueue *vq,
        return -EIO;
 }
 
+static inline int virtqueue_add_packed_in_order(struct vring_virtqueue *vq,
+                                               struct scatterlist *sgs[],
+                                               unsigned int total_sg,
+                                               unsigned int out_sgs,
+                                               unsigned int in_sgs,
+                                               void *data,
+                                               void *ctx,
+                                               bool premapped,
+                                               gfp_t gfp)
+{
+       struct vring_packed_desc *desc;
+       struct scatterlist *sg;
+       unsigned int i, n, c, err_idx, total_len = 0;
+       __le16 head_flags, flags;
+       u16 head, avail_used_flags;
+       int err;
+
+       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)) {
+               err = virtqueue_add_indirect_packed(vq, sgs, total_sg, out_sgs,
+                                                   in_sgs, data, premapped, 
gfp,
+                                                   vq->packed.next_avail_idx);
+               if (err != -ENOMEM) {
+                       END_USE(vq);
+                       return err;
+               }
+
+               /* fall back on direct */
+       }
+
+       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;
+
+       if (unlikely(vq->vq.num_free < total_sg)) {
+               pr_debug("Can't add buf len %i - avail = %i\n",
+                        total_sg, vq->vq.num_free);
+               END_USE(vq);
+               return -ENOSPC;
+       }
+
+       c = 0;
+       for (n = 0; n < out_sgs + in_sgs; n++) {
+               for (sg = sgs[n]; sg; sg = sg_next(sg)) {
+                       dma_addr_t addr;
+                       u32 len;
+
+                       if (vring_map_one_sg(vq, sg, n < out_sgs ?
+                                            DMA_TO_DEVICE : DMA_FROM_DEVICE,
+                                            &addr, &len, premapped))
+                               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(len);
+                       desc[i].id = cpu_to_le16(head);
+
+                       if (unlikely(vq->use_dma_api)) {
+                               vq->packed.desc_extra[i].addr = premapped ?
+                                     DMA_MAPPING_ERROR: addr;
+                               vq->packed.desc_extra[i].len = len;
+                               vq->packed.desc_extra[i].flags =
+                                       le16_to_cpu(flags);
+                       }
+
+                       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;
+                               vq->packed.avail_wrap_counter ^= 1;
+                       }
+
+                       total_len += len;
+               }
+       }
+
+       /* We're using some buffers from the free list. */
+       vq->vq.num_free -= total_sg;
+
+       /* Update free pointer */
+       vq->packed.next_avail_idx = i;
+
+       /* Store token. */
+       vq->packed.desc_state[head].num = total_sg;
+       vq->packed.desc_state[head].data = data;
+       vq->packed.desc_state[head].indir_desc = ctx;
+       vq->packed.desc_state[head].total_len = total_len;
+
+       /*
+        * 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 += total_sg;
+
+       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_extra_packed(vq, &vq->packed.desc_extra[i]);
+               i++;
+               if (i >= vq->packed.vring.num)
+                       i = 0;
+       }
+
+       END_USE(vq);
+       return -EIO;
+}
+
 static bool virtqueue_kick_prepare_packed(struct vring_virtqueue *vq)
 {
        u16 new, old, off_wrap, flags, wrap_counter, event_idx;
@@ -1792,10 +2051,81 @@ static void update_last_used_idx_packed(struct 
vring_virtqueue *vq,
                                cpu_to_le16(vq->last_used_idx));
 }
 
+static bool more_used_packed_in_order(const struct vring_virtqueue *vq)
+{
+       if (vq->batch_last.id != vq->packed.vring.num)
+               return true;
+
+       return virtqueue_poll_packed(vq, READ_ONCE(vq->last_used_idx));
+}
+
+static void *virtqueue_get_buf_ctx_packed_in_order(struct vring_virtqueue *vq,
+                                                  unsigned int *len,
+                                                  void **ctx)
+{
+       unsigned int num = vq->packed.vring.num;
+       u16 last_used, last_used_idx;
+       bool used_wrap_counter;
+       void *ret;
+
+       START_USE(vq);
+
+       if (unlikely(vq->broken)) {
+               END_USE(vq);
+               return NULL;
+       }
+
+       last_used_idx = vq->last_used_idx;
+       used_wrap_counter = packed_used_wrap_counter(last_used_idx);
+       last_used = packed_last_used(last_used_idx);
+
+       if (vq->batch_last.id == num) {
+               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);
+               vq->batch_last.id =
+                       le16_to_cpu(vq->packed.vring.desc[last_used].id);
+               vq->batch_last.len =
+                       le32_to_cpu(vq->packed.vring.desc[last_used].len);
+       }
+
+       if (vq->batch_last.id == last_used) {
+               vq->batch_last.id = num;
+               *len = vq->batch_last.len;
+       } else
+               *len = vq->packed.desc_state[last_used].total_len;
+
+       if (unlikely(last_used >= num)) {
+               BAD_RING(vq, "id %u out of range\n", last_used);
+               return NULL;
+       }
+       if (unlikely(!vq->packed.desc_state[last_used].data)) {
+               BAD_RING(vq, "id %u is not a head!\n", last_used);
+               return NULL;
+       }
+
+       /* detach_buf_packed clears data, so grab it now. */
+       ret = vq->packed.desc_state[last_used].data;
+       detach_buf_packed_in_order(vq, last_used, ctx);
+
+       update_last_used_idx_packed(vq, last_used, last_used,
+                                   used_wrap_counter);
+
+       LAST_ADD_TIME_INVALID(vq);
+
+       END_USE(vq);
+       return ret;
+}
+
 static void *virtqueue_get_buf_ctx_packed(struct vring_virtqueue *vq,
                                          unsigned int *len,
                                          void **ctx)
 {
+       unsigned int num = vq->packed.vring.num;
        u16 last_used, id, last_used_idx;
        bool used_wrap_counter;
        void *ret;
@@ -1822,7 +2152,7 @@ static void *virtqueue_get_buf_ctx_packed(struct 
vring_virtqueue *vq,
        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)) {
+       if (unlikely(id >= num)) {
                BAD_RING(vq, "id %u out of range\n", id);
                return NULL;
        }
@@ -1963,7 +2293,7 @@ static void *virtqueue_detach_unused_buf_packed(struct 
vring_virtqueue *vq)
                        continue;
                /* detach_buf clears data, so grab it now. */
                buf = vq->packed.desc_state[i].data;
-               detach_buf_packed(vq, i, NULL);
+               detach_buf_packed_in_order(vq, i, NULL);
                END_USE(vq);
                return buf;
        }
@@ -1989,6 +2319,8 @@ static struct vring_desc_extra 
*vring_alloc_desc_extra(unsigned int num)
        for (i = 0; i < num - 1; i++)
                desc_extra[i].next = i + 1;
 
+       desc_extra[num - 1].next = 0;
+
        return desc_extra;
 }
 
@@ -2120,8 +2452,12 @@ static void virtqueue_vring_attach_packed(struct 
vring_virtqueue *vq,
 {
        vq->packed = *vring_packed;
 
-       /* Put everything in free lists. */
-       vq->free_head = 0;
+       if (virtqueue_is_in_order(vq))
+               vq->batch_last.id = vq->split.vring.num;
+       else {
+               /* Put everything in free lists. */
+               vq->free_head = 0;
+       }
 }
 
 static void virtqueue_reset_packed(struct vring_virtqueue *vq)
@@ -2168,13 +2504,14 @@ static struct virtqueue 
*__vring_new_virtqueue_packed(unsigned int index,
 #else
        vq->broken = false;
 #endif
-       vq->layout = PACKED;
        vq->dma_dev = dma_dev;
        vq->use_dma_api = vring_use_dma_api(vdev);
 
        vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) &&
                !context;
        vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
+       vq->layout = virtio_has_feature(vdev, VIRTIO_F_IN_ORDER) ?
+                    PACKED_IN_ORDER : PACKED;
 
        if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM))
                vq->weak_barriers = false;
@@ -2284,9 +2621,39 @@ static const struct virtqueue_ops packed_ops = {
        .reset = virtqueue_reset_packed,
 };
 
+static const struct virtqueue_ops split_in_order_ops = {
+       .add = virtqueue_add_split,
+       .get = virtqueue_get_buf_ctx_split_in_order,
+       .kick_prepare = virtqueue_kick_prepare_split,
+       .disable_cb = virtqueue_disable_cb_split,
+       .enable_cb_delayed = virtqueue_enable_cb_delayed_split,
+       .enable_cb_prepare = virtqueue_enable_cb_prepare_split,
+       .poll = virtqueue_poll_split,
+       .detach_unused_buf = virtqueue_detach_unused_buf_split,
+       .more_used = more_used_split_in_order,
+       .resize = virtqueue_resize_split,
+       .reset = virtqueue_reset_split,
+};
+
+static const struct virtqueue_ops packed_in_order_ops = {
+       .add = virtqueue_add_packed_in_order,
+       .get = virtqueue_get_buf_ctx_packed_in_order,
+       .kick_prepare = virtqueue_kick_prepare_packed,
+       .disable_cb = virtqueue_disable_cb_packed,
+       .enable_cb_delayed = virtqueue_enable_cb_delayed_packed,
+       .enable_cb_prepare = virtqueue_enable_cb_prepare_packed,
+       .poll = virtqueue_poll_packed,
+       .detach_unused_buf = virtqueue_detach_unused_buf_packed,
+       .more_used = more_used_packed_in_order,
+       .resize = virtqueue_resize_packed,
+       .reset = virtqueue_reset_packed,
+};
+
 static const struct virtqueue_ops *const all_ops[VQ_TYPE_MAX] = {
        [SPLIT] = &split_ops,
-       [PACKED] = &packed_ops
+       [PACKED] = &packed_ops,
+       [SPLIT_IN_ORDER] = &split_in_order_ops,
+       [PACKED_IN_ORDER] = &packed_in_order_ops,
 };
 
 static int virtqueue_disable_and_recycle(struct virtqueue *_vq,
@@ -2342,6 +2709,12 @@ static int virtqueue_enable_after_reset(struct virtqueue 
*_vq)
        case PACKED:                                                    \
                ret = all_ops[PACKED]->op(vq, ##__VA_ARGS__);           \
                break;                                                  \
+       case SPLIT_IN_ORDER:                                            \
+               ret = all_ops[SPLIT_IN_ORDER]->op(vq, ##__VA_ARGS__);   \
+               break;                                                  \
+       case PACKED_IN_ORDER:                                           \
+               ret = all_ops[PACKED_IN_ORDER]->op(vq, ##__VA_ARGS__);  \
+               break;                                                  \
        default:                                                        \
                BUG();                                                  \
                break;                                                  \
@@ -2358,10 +2731,16 @@ static int virtqueue_enable_after_reset(struct 
virtqueue *_vq)
        case PACKED:                                    \
                all_ops[PACKED]->op(vq, ##__VA_ARGS__); \
                break;                                  \
-       default:                                        \
-               BUG();                                  \
-               break;                                  \
-       }                                               \
+       case SPLIT_IN_ORDER:                                            \
+               all_ops[SPLIT_IN_ORDER]->op(vq, ##__VA_ARGS__); \
+               break;                                                  \
+       case PACKED_IN_ORDER:                                           \
+               all_ops[PACKED_IN_ORDER]->op(vq, ##__VA_ARGS__);        \
+               break;                                                  \
+       default:                                                        \
+               BUG();                                                  \
+               break;                                                  \
+       }                                                               \
 })
 
 static inline int virtqueue_add(struct virtqueue *_vq,
@@ -3076,6 +3455,8 @@ void vring_transport_features(struct virtio_device *vdev)
                        break;
                case VIRTIO_F_NOTIFICATION_DATA:
                        break;
+               case VIRTIO_F_IN_ORDER:
+                       break;
                default:
                        /* We don't understand this bit. */
                        __virtio_clear_bit(vdev, i);
-- 
2.39.5


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