commit 844619147c5110f335cbbbad51cda6a898c7ef33
author Jonah Palmer <jonah.palmer@oracle.com> Wed Jul 10 08:55:17 2024 -0400
committer Michael S. Tsirkin <mst@redhat.com> Sun Jul 21 14:45:56 2024 -0400
tree 1ed8cf01d18098c3351b5619e7947052c274c4d0
parent b44135daa3721778f4656ca3c15bd9b3060f1176

virtio: virtqueue_ordered_flush - VIRTIO_F_IN_ORDER support

Add VIRTIO_F_IN_ORDER feature support for the virtqueue_flush operation.

The goal of the virtqueue_ordered_flush operation when the
VIRTIO_F_IN_ORDER feature has been negotiated is to write elements to
the used/descriptor ring in-order and then update used_idx.

The function iterates through the VirtQueueElement used_elems array
in-order starting at vq->used_idx. If the element is valid (filled), the
element is written to the used/descriptor ring. This process continues
until we find an invalid (not filled) element.

For packed VQs, the first entry (at vq->used_idx) is written to the
descriptor ring last so the guest doesn't see any invalid descriptors.

If any elements were written, the used_idx is updated.

Signed-off-by: Jonah Palmer <jonah.palmer@oracle.com>
Message-Id: <20240710125522.4168043-5-jonah.palmer@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Eugenio Pérez <eperezma@redhat.com>