Initialize sequence variables for VirtQueue and VirtQueueElement structures. A VirtQueue's sequence variables are initialized when a VirtQueue is being created or reset. A VirtQueueElement's sequence variable is initialized when a VirtQueueElement is being initialized. These variables will be used to support the VIRTIO_F_IN_ORDER feature.
A VirtQueue's used_seq_idx represents the next expected index in a sequence of VirtQueueElements to be processed (put on the used ring). The next VirtQueueElement added to the used ring must match this sequence number before additional elements can be safely added to the used ring. It's also particularly useful for helping find the number of new elements added to the used ring. A VirtQueue's current_seq_idx represents the current sequence index. This value is essentially a counter where the value is assigned to a new VirtQueueElement and then incremented. Given its uint16_t type, this sequence number can be between 0 and 65,535. A VirtQueueElement's seq_idx represents the sequence number assigned to the VirtQueueElement when it was created. This value must match with the VirtQueue's used_seq_idx before the element can be put on the used ring by the device. Signed-off-by: Jonah Palmer <jonah.pal...@oracle.com> --- hw/virtio/virtio.c | 18 ++++++++++++++++++ include/hw/virtio/virtio.h | 1 + 2 files changed, 19 insertions(+) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index fb6b4ccd83..069d96df99 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -132,6 +132,10 @@ struct VirtQueue uint16_t used_idx; bool used_wrap_counter; + /* In-Order sequence indices */ + uint16_t used_seq_idx; + uint16_t current_seq_idx; + /* Last used index value we have signalled on */ uint16_t signalled_used; @@ -1621,6 +1625,11 @@ static void *virtqueue_split_pop(VirtQueue *vq, size_t sz) elem->in_sg[i] = iov[out_num + i]; } + /* Assign sequence index for in-order processing */ + if (virtio_vdev_has_feature(vdev, VIRTIO_F_IN_ORDER)) { + elem->seq_idx = vq->current_seq_idx++; + } + vq->inuse++; trace_virtqueue_pop(vq, elem, elem->in_num, elem->out_num); @@ -1760,6 +1769,11 @@ static void *virtqueue_packed_pop(VirtQueue *vq, size_t sz) vq->shadow_avail_idx = vq->last_avail_idx; vq->shadow_avail_wrap_counter = vq->last_avail_wrap_counter; + /* Assign sequence index for in-order processing */ + if (virtio_vdev_has_feature(vdev, VIRTIO_F_IN_ORDER)) { + elem->seq_idx = vq->current_seq_idx++; + } + trace_virtqueue_pop(vq, elem, elem->in_num, elem->out_num); done: address_space_cache_destroy(&indirect_desc_cache); @@ -2087,6 +2101,8 @@ static void __virtio_queue_reset(VirtIODevice *vdev, uint32_t i) vdev->vq[i].notification = true; vdev->vq[i].vring.num = vdev->vq[i].vring.num_default; vdev->vq[i].inuse = 0; + vdev->vq[i].used_seq_idx = 0; + vdev->vq[i].current_seq_idx = 0; virtio_virtqueue_reset_region_cache(&vdev->vq[i]); } @@ -2334,6 +2350,8 @@ 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].used_elems = g_new0(VirtQueueElement, queue_size); + vdev->vq[i].used_seq_idx = 0; + vdev->vq[i].current_seq_idx = 0; return &vdev->vq[i]; } diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h index b3c74a1bca..910b2a3427 100644 --- a/include/hw/virtio/virtio.h +++ b/include/hw/virtio/virtio.h @@ -75,6 +75,7 @@ typedef struct VirtQueueElement hwaddr *out_addr; struct iovec *in_sg; struct iovec *out_sg; + uint16_t seq_idx; } VirtQueueElement; #define VIRTIO_QUEUE_MAX 1024 -- 2.39.3