[PATCH 01/33] vhost: introduce vhost_ops->vhost_set_vring_enable_supported method

[Vladimir Sementsov-Ogievskiy]

Remove vhost-user specific hack from generic code.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@yandex-team.ru>
---
 hw/virtio/vhost-user.c            |  8 ++++++++
 hw/virtio/vhost.c                 | 15 ++++++---------
 include/hw/virtio/vhost-backend.h |  2 ++
 3 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 1e1d6b0d6e..1b2879a90c 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -1230,6 +1230,12 @@ static int vhost_user_set_vring_base(struct vhost_dev 
*dev,
     return vhost_set_vring(dev, VHOST_USER_SET_VRING_BASE, ring, false);
 }
 
+static bool vhost_user_set_vring_enable_supported(struct vhost_dev *dev)
+{
+    return virtio_has_feature(dev->backend_features,
+                              VHOST_USER_F_PROTOCOL_FEATURES);
+}
+
 static int vhost_user_set_vring_enable(struct vhost_dev *dev, int enable)
 {
     int i;
@@ -3032,6 +3038,8 @@ const VhostOps user_ops = {
         .vhost_reset_device = vhost_user_reset_device,
         .vhost_get_vq_index = vhost_user_get_vq_index,
         .vhost_set_vring_enable = vhost_user_set_vring_enable,
+        .vhost_set_vring_enable_supported =
+            vhost_user_set_vring_enable_supported,
         .vhost_requires_shm_log = vhost_user_requires_shm_log,
         .vhost_migration_done = vhost_user_migration_done,
         .vhost_net_set_mtu = vhost_user_net_set_mtu,
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 6557c58d12..c33dad4acd 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -1986,15 +1986,12 @@ static int vhost_dev_set_vring_enable(struct vhost_dev 
*hdev, int enable)
         return 0;
     }
 
-    /*
-     * For vhost-user devices, if VHOST_USER_F_PROTOCOL_FEATURES has not
-     * been negotiated, the rings start directly in the enabled state, and
-     * .vhost_set_vring_enable callback will fail since
-     * VHOST_USER_SET_VRING_ENABLE is not supported.
-     */
-    if (hdev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER &&
-        !virtio_has_feature(hdev->backend_features,
-                            VHOST_USER_F_PROTOCOL_FEATURES)) {
+    if (hdev->vhost_ops->vhost_set_vring_enable_supported &&
+        !hdev->vhost_ops->vhost_set_vring_enable_supported(hdev)) {
+        /*
+         * This means, that rings are always enabled, and disable/enable
+         * API is not supported.
+         */
         return 0;
     }
 
diff --git a/include/hw/virtio/vhost-backend.h 
b/include/hw/virtio/vhost-backend.h
index d6df209a2f..f65fa26298 100644
--- a/include/hw/virtio/vhost-backend.h
+++ b/include/hw/virtio/vhost-backend.h
@@ -105,6 +105,7 @@ typedef int (*vhost_reset_device_op)(struct vhost_dev *dev);
 typedef int (*vhost_get_vq_index_op)(struct vhost_dev *dev, int idx);
 typedef int (*vhost_set_vring_enable_op)(struct vhost_dev *dev,
                                          int enable);
+typedef bool (*vhost_set_vring_enable_supported_op)(struct vhost_dev *dev);
 typedef bool (*vhost_requires_shm_log_op)(struct vhost_dev *dev);
 typedef int (*vhost_migration_done_op)(struct vhost_dev *dev,
                                        char *mac_addr);
@@ -193,6 +194,7 @@ typedef struct VhostOps {
     vhost_reset_device_op vhost_reset_device;
     vhost_get_vq_index_op vhost_get_vq_index;
     vhost_set_vring_enable_op vhost_set_vring_enable;
+    vhost_set_vring_enable_supported_op vhost_set_vring_enable_supported;
     vhost_requires_shm_log_op vhost_requires_shm_log;
     vhost_migration_done_op vhost_migration_done;
     vhost_vsock_set_guest_cid_op vhost_vsock_set_guest_cid;
-- 
2.48.1