From b44135daa3721778f4656ca3c15bd9b3060f1176 Mon Sep 17 00:00:00 2001 From: Jonah Palmer Date: Wed, 10 Jul 2024 08:55:16 -0400 Subject: [PATCH] virtio: virtqueue_ordered_fill - VIRTIO_F_IN_ORDER support MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add VIRTIO_F_IN_ORDER feature support for the virtqueue_fill operation. The goal of the virtqueue_ordered_fill operation when the VIRTIO_F_IN_ORDER feature has been negotiated is to search for this now-used element, set its length, and mark the element as filled in the VirtQueue's used_elems array. By marking the element as filled, it will indicate that this element has been processed and is ready to be flushed, so long as the element is in-order. Reviewed-by: Eugenio Pérez Signed-off-by: Jonah Palmer Message-Id: <20240710125522.4168043-4-jonah.palmer@oracle.com> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/virtio/virtio.c | 44 +++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 43 insertions(+), 1 deletion(-) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 98eb601b09..0000a7b41c 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -872,6 +872,46 @@ static void virtqueue_packed_fill(VirtQueue *vq, const VirtQueueElement *elem, vq->used_elems[idx].ndescs = elem->ndescs; } +static void virtqueue_ordered_fill(VirtQueue *vq, const VirtQueueElement *elem, + unsigned int len) +{ + unsigned int i, steps, max_steps; + + i = vq->used_idx % vq->vring.num; + steps = 0; + /* + * We shouldn't need to increase 'i' by more than the distance + * between used_idx and last_avail_idx. + */ + max_steps = (vq->last_avail_idx - vq->used_idx) % vq->vring.num; + + /* Search for element in vq->used_elems */ + while (steps <= max_steps) { + /* Found element, set length and mark as filled */ + if (vq->used_elems[i].index == elem->index) { + vq->used_elems[i].len = len; + vq->used_elems[i].in_order_filled = true; + break; + } + + i += vq->used_elems[i].ndescs; + steps += vq->used_elems[i].ndescs; + + if (i >= vq->vring.num) { + i -= vq->vring.num; + } + } + + /* + * We should be able to find a matching VirtQueueElement in + * used_elems. If we don't, this is an error. + */ + if (steps >= max_steps) { + qemu_log_mask(LOG_GUEST_ERROR, "%s: %s cannot fill buffer id %u\n", + __func__, vq->vdev->name, elem->index); + } +} + static void virtqueue_packed_fill_desc(VirtQueue *vq, const VirtQueueElement *elem, unsigned int idx, @@ -922,7 +962,9 @@ void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem, return; } - if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) { + if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_IN_ORDER)) { + virtqueue_ordered_fill(vq, elem, len); + } else 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);