[RFC PATCH v3 18/20] hw/virtio: validate F_STANDALONE also supports other protocol features

[Alex Bennée]

If the backend advertises F_STANDALONE validate that it supports the
other mandatory features or error out.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
---
 hw/virtio/vhost-user.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 28b021d5d3..3116b3e46a 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -74,6 +74,8 @@ enum VhostUserProtocolFeature {
     /* Feature 14 reserved for VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS. */
     VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS = 15,
     VHOST_USER_PROTOCOL_F_STATUS = 16,
+    VHOST_USER_PROTOCOL_F_XEN_MMAP = 17,
+    VHOST_USER_PROTOCOL_F_STANDALONE = 18,
     VHOST_USER_PROTOCOL_F_MAX
 };
 
@@ -2048,6 +2050,21 @@ static int vhost_user_backend_init(struct vhost_dev 
*dev, void *opaque,
             }
         }
 
+        /*
+         * If the backend supports F_STANDALONE we should validate it
+         * supports the other features we expect. We can't check for
+         * F_CONFIG support until we know if there is a config space
+         * to manage.
+         */
+        if (virtio_has_feature(protocol_features,
+                               VHOST_USER_PROTOCOL_F_STANDALONE)) {
+            if (!virtio_has_feature(protocol_features, 
VHOST_USER_PROTOCOL_F_STATUS)) {
+                error_setg(errp, "vhost-user device expecting F_STANDALONE 
device to also "
+                           "support F_STATUS but it does not.");
+                return -EPROTO;
+            }
+        }
+
         /* final set of protocol features */
         dev->protocol_features = protocol_features;
         err = vhost_user_set_protocol_features(dev, dev->protocol_features);
-- 
2.39.2