Re: [PATCH 17/19] virtio_ring: move next_avail_idx to vring_virtqueue

From: Eugenio Perez Martin
Date: Wed Mar 26 2025 - 10:02:33 EST


On Mon, Mar 24, 2025 at 7:01 AM Jason Wang <jasowang@xxxxxxxxxx> wrote:
>
> This variable is used by packed virtqueue now, moving it to
> vring_virtqueue to make it possible to be reused by split virtqueue
> in-order implementation.
>

Acked-by: Eugenio Pérez <eperezma@xxxxxxxxxx>

> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---
> drivers/virtio/virtio_ring.c | 22 +++++++++++-----------
> 1 file changed, 11 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index bd4faf04862c..a1a8cd931052 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -138,9 +138,6 @@ struct vring_virtqueue_packed {
> /* Avail used flags. */
> u16 avail_used_flags;
>
> - /* Index of the next avail descriptor. */
> - u16 next_avail_idx;
> -
> /*
> * Last written value to driver->flags in
> * guest byte order.
> @@ -214,6 +211,9 @@ struct vring_virtqueue {
> */
> u16 last_used_idx;
>
> + /* Index of the next avail descriptor. */
> + u16 next_avail_idx;
> +
> /* Hint for event idx: already triggered no need to disable. */
> bool event_triggered;
>
> @@ -448,6 +448,7 @@ static void virtqueue_init(struct vring_virtqueue *vq, u32 num)
> else
> vq->last_used_idx = 0;
>
> + vq->next_avail_idx = 0;
> vq->event_triggered = false;
> vq->num_added = 0;
>
> @@ -1350,7 +1351,7 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
> u16 head, id;
> dma_addr_t addr;
>
> - head = vq->packed.next_avail_idx;
> + head = vq->next_avail_idx;
> desc = alloc_indirect_packed(total_sg, gfp);
> if (!desc)
> return -ENOMEM;
> @@ -1431,7 +1432,7 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
> 1 << VRING_PACKED_DESC_F_AVAIL |
> 1 << VRING_PACKED_DESC_F_USED;
> }
> - vq->packed.next_avail_idx = n;
> + vq->next_avail_idx = n;
> vq->free_head = vq->packed.desc_extra[id].next;
>
> /* Store token and indirect buffer state. */
> @@ -1501,7 +1502,7 @@ static inline int virtqueue_add_packed(struct vring_virtqueue *vq,
> /* fall back on direct */
> }
>
> - head = vq->packed.next_avail_idx;
> + head = vq->next_avail_idx;
> avail_used_flags = vq->packed.avail_used_flags;
>
> WARN_ON_ONCE(total_sg > vq->packed.vring.num && !vq->indirect);
> @@ -1569,7 +1570,7 @@ static inline int virtqueue_add_packed(struct vring_virtqueue *vq,
> vq->vq.num_free -= descs_used;
>
> /* Update free pointer */
> - vq->packed.next_avail_idx = i;
> + vq->next_avail_idx = i;
> vq->free_head = curr;
>
> /* Store token. */
> @@ -1633,8 +1634,8 @@ static bool virtqueue_kick_prepare_packed(struct vring_virtqueue *vq)
> */
> virtio_mb(vq->weak_barriers);
>
> - old = vq->packed.next_avail_idx - vq->num_added;
> - new = vq->packed.next_avail_idx;
> + old = vq->next_avail_idx - vq->num_added;
> + new = vq->next_avail_idx;
> vq->num_added = 0;
>
> snapshot.u32 = *(u32 *)vq->packed.vring.device;
> @@ -2083,7 +2084,6 @@ static int vring_alloc_state_extra_packed(struct vring_virtqueue_packed *vring_p
> static void virtqueue_vring_init_packed(struct vring_virtqueue_packed *vring_packed,
> bool callback)
> {
> - vring_packed->next_avail_idx = 0;
> vring_packed->avail_wrap_counter = 1;
> vring_packed->event_flags_shadow = 0;
> vring_packed->avail_used_flags = 1 << VRING_PACKED_DESC_F_AVAIL;
> @@ -2977,7 +2977,7 @@ u32 vring_notification_data(struct virtqueue *_vq)
> u16 next;
>
> if (vq->packed_ring)
> - next = (vq->packed.next_avail_idx &
> + next = (vq->next_avail_idx &
> ~(-(1 << VRING_PACKED_EVENT_F_WRAP_CTR))) |
> vq->packed.avail_wrap_counter <<
> VRING_PACKED_EVENT_F_WRAP_CTR;
> --
> 2.42.0
>