libvhost-user: implement in-band notifications

Add support for VHOST_USER_PROTOCOL_F_IN_BAND_NOTIFICATIONS, but
as it's not desired by default, don't enable it unless the device
implementation opts in by returning it from its protocol features
callback.

Note that I updated vu_set_vring_err_exec(), but didn't add any
sending of the VHOST_USER_SLAVE_VRING_ERR message as there's no
write to the err_fd today either.

This also adds vu_queue_notify_sync() which can be used to force
a synchronous notification if inband notifications are supported.
Previously, I had left out the slave->master direction handling
of F_REPLY_ACK, this now adds some code to support it as well.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Message-Id: <20200123081708.7817-7-johannes@sipsolutions.net>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/contrib/libvhost-user/libvhost-user.h b/contrib/libvhost-user/libvhost-user.h
index 5cb7708559..6fc8000e99 100644
--- a/contrib/libvhost-user/libvhost-user.h
+++ b/contrib/libvhost-user/libvhost-user.h
@@ -54,6 +54,7 @@ enum VhostUserProtocolFeature {
     VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD = 10,
     VHOST_USER_PROTOCOL_F_HOST_NOTIFIER = 11,
     VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD = 12,
+    VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS = 14,
 
     VHOST_USER_PROTOCOL_F_MAX
 };
@@ -95,6 +96,7 @@ typedef enum VhostUserRequest {
     VHOST_USER_GET_INFLIGHT_FD = 31,
     VHOST_USER_SET_INFLIGHT_FD = 32,
     VHOST_USER_GPU_SET_SOCKET = 33,
+    VHOST_USER_VRING_KICK = 35,
     VHOST_USER_MAX
 } VhostUserRequest;
 
@@ -103,6 +105,8 @@ typedef enum VhostUserSlaveRequest {
     VHOST_USER_SLAVE_IOTLB_MSG = 1,
     VHOST_USER_SLAVE_CONFIG_CHANGE_MSG = 2,
     VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG = 3,
+    VHOST_USER_SLAVE_VRING_CALL = 4,
+    VHOST_USER_SLAVE_VRING_ERR = 5,
     VHOST_USER_SLAVE_MAX
 }  VhostUserSlaveRequest;
 
@@ -529,6 +533,16 @@ bool vu_queue_empty(VuDev *dev, VuVirtq *vq);
 void vu_queue_notify(VuDev *dev, VuVirtq *vq);
 
 /**
+ * vu_queue_notify_sync:
+ * @dev: a VuDev context
+ * @vq: a VuVirtq queue
+ *
+ * Request to notify the queue via callfd (skipped if unnecessary)
+ * or sync message if possible.
+ */
+void vu_queue_notify_sync(VuDev *dev, VuVirtq *vq);
+
+/**
  * vu_queue_pop:
  * @dev: a VuDev context
  * @vq: a VuVirtq queue