vhost: mask VIRTIO_F_RING_RESET for vhost and vhost-user devices

Commit 69e1c14aa2 ("virtio: core: vq reset feature negotation support")
enabled VIRTIO_F_RING_RESET by default for all virtio devices.

This feature is not currently emulated by QEMU, so for vhost and
vhost-user devices we need to make sure it is supported by the offloaded
device emulation (in-kernel or in another process).
To do this we need to add VIRTIO_F_RING_RESET to the features bitmap
passed to vhost_get_features(). This way it will be masked if the device
does not support it.

This issue was initially discovered with vhost-vsock and vhost-user-vsock,
and then also tested with vhost-user-rng which confirmed the same issue.
They fail when sending features through VHOST_SET_FEATURES ioctl or
VHOST_USER_SET_FEATURES message, since VIRTIO_F_RING_RESET is negotiated
by the guest (Linux >= v6.0), but not supported by the device.

Fixes: 69e1c14aa2 ("virtio: core: vq reset feature negotation support")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1318
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20221121101101.29400-1-sgarzare@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Acked-by: Jason Wang <jasowang@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
index 16ad400889..0d5190accf 100644
--- a/hw/block/vhost-user-blk.c
+++ b/hw/block/vhost-user-blk.c
@@ -52,6 +52,7 @@ static const int user_feature_bits[] = {
     VIRTIO_F_NOTIFY_ON_EMPTY,
     VIRTIO_F_RING_PACKED,
     VIRTIO_F_IOMMU_PLATFORM,
+    VIRTIO_F_RING_RESET,
     VHOST_INVALID_FEATURE_BIT
 };