[dpdk-dev] [PATCH] net/virtio-user: fix advertising of protocol features

[Olivier Matz]

When connected to a vhost-user backend, the flag
VHOST_USER_F_PROTOCOL_FEATURES is not advertised, preventing to do
multiqueue (the VHOST_USER_PROTOCOL_F_MQ protocol feature is ignored by
some backends if the VHOST_USER_F_PROTOCOL_FEATURES feature is not set).

When setting vhost-user features, advertise this flag if it was
advertised by our peer.

Fixes: 8e7561054ac7 ("net/virtio: support vhost-user protocol features")
Cc: stable at dpdk.org

Suggested-by: Maxime Coquelin <maxime.coquelin at redhat.com>
Signed-off-by: Olivier Matz <olivier.matz at 6wind.com>
---
 drivers/net/virtio/virtio_user/vhost_user.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/virtio/virtio_user/vhost_user.c b/drivers/net/virtio/virtio_user/vhost_user.c
index b93e65c60b..5e8a5c293e 100644
--- a/drivers/net/virtio/virtio_user/vhost_user.c
+++ b/drivers/net/virtio/virtio_user/vhost_user.c
@@ -298,6 +298,10 @@ vhost_user_sock(struct virtio_user_dev *dev,
 			msg.flags |= VHOST_USER_NEED_REPLY_MASK;
 		/* Fallthrough */
 	case VHOST_USER_SET_FEATURES:
+		msg.payload.u64 = *((__u64 *)arg) | (dev->device_features &
+			(1ULL << VHOST_USER_F_PROTOCOL_FEATURES));
+		msg.size = sizeof(m.payload.u64);
+		break;
 	case VHOST_USER_SET_PROTOCOL_FEATURES:
 	case VHOST_USER_SET_LOG_BASE:
 		msg.payload.u64 = *((__u64 *)arg);
-- 
2.25.1