From: Halil Pasic <pasic@linux.ibm.com>

Not having VIRTIO_F_RING_PACKED in feature_bits[] is a problem when the
vhost-vsock device does not offer the feature bit VIRTIO_F_RING_PACKED
but the in QEMU device is configured to try to use the packed layout
(the virtio property "packed" is on).

As of today, the  Linux kernel vhost-vsock device does not support the
packed queue layout (as vhost does not support packed), and does not
offer VIRTIO_F_RING_PACKED. Thus when for example a vhost-vsock-ccw is
used with packed=on, VIRTIO_F_RING_PACKED ends up being negotiated,
despite the fact that the device does not actually support it, and
one gets to keep the pieces.

Fixes: 74b3e46630 ("virtio: add property to enable packed virtqueue")
Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Message-Id: <20240429113334.2454197-1-pasic@linux.ibm.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/virtio/vhost-vsock-common.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hw/virtio/vhost-vsock-common.c b/hw/virtio/vhost-vsock-common.c
index 12ea87d7a7..fd88df2560 100644
--- a/hw/virtio/vhost-vsock-common.c
+++ b/hw/virtio/vhost-vsock-common.c
@@ -22,6 +22,7 @@
 const int feature_bits[] = {
     VIRTIO_VSOCK_F_SEQPACKET,
     VIRTIO_F_RING_RESET,
+    VIRTIO_F_RING_PACKED,
     VHOST_INVALID_FEATURE_BIT
 };
 
-- 
MST