[RFC PATCH v5 21/26] vhost: Add vhost_svq_valid_guest_features to shadow vq

["Eugenio Pérez" <eperezma@redhat.com>]

This allows it to test if the guest has aknowledge an invalid transport
feature for SVQ. This will include packed vq layout or event_idx,
where VirtIO device needs help from SVQ.

There is not needed at this moment, but since SVQ will not re-negotiate
features again with the guest, a failure in acknowledge them is fatal
for SVQ.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 hw/virtio/vhost-shadow-virtqueue.h | 1 +
 hw/virtio/vhost-shadow-virtqueue.c | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/hw/virtio/vhost-shadow-virtqueue.h b/hw/virtio/vhost-shadow-virtqueue.h
index 946b2c6295..ac55588009 100644
--- a/hw/virtio/vhost-shadow-virtqueue.h
+++ b/hw/virtio/vhost-shadow-virtqueue.h
@@ -16,6 +16,7 @@
 typedef struct VhostShadowVirtqueue VhostShadowVirtqueue;
 
 bool vhost_svq_valid_device_features(uint64_t *features);
+bool vhost_svq_valid_guest_features(uint64_t *features);
 
 void vhost_svq_set_svq_kick_fd(VhostShadowVirtqueue *svq, int svq_kick_fd);
 void vhost_svq_set_guest_call_notifier(VhostShadowVirtqueue *svq, int call_fd);
diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c
index 6e0508a231..cb9ffcb015 100644
--- a/hw/virtio/vhost-shadow-virtqueue.c
+++ b/hw/virtio/vhost-shadow-virtqueue.c
@@ -62,6 +62,12 @@ bool vhost_svq_valid_device_features(uint64_t *dev_features)
     return true;
 }
 
+/* If the guest is using some of these, SVQ cannot communicate */
+bool vhost_svq_valid_guest_features(uint64_t *guest_features)
+{
+    return true;
+}
+
 /* Forward guest notifications */
 static void vhost_handle_guest_kick(EventNotifier *n)
 {
-- 
2.27.0