[PATCH v3 1/7] vhost: add vhost_reset_owner op

[Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>]

Add a VhostOps callback issuing VHOST_RESET_OWNER, wired up for the kernel
backend.  The CPR (checkpoint-restore) path uses it to release device
ownership on the source so the destination can reclaim it later with
VHOST_SET_OWNER.

Originally-by: Mark Kanda <mark.kanda@oracle.com>
Originally-by: Steve Sistare <steven.sistare@oracle.com>
Originally-by: Ben Chaney <bchaney@akamai.com>
Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
---
 hw/virtio/vhost-kernel.c          | 6 ++++++
 include/hw/virtio/vhost-backend.h | 1 +
 2 files changed, 7 insertions(+)

diff --git a/hw/virtio/vhost-kernel.c b/hw/virtio/vhost-kernel.c
index 3390b48c6f1..55d316b88e9 100644
--- a/hw/virtio/vhost-kernel.c
+++ b/hw/virtio/vhost-kernel.c
@@ -261,6 +261,11 @@ static int vhost_kernel_set_owner(struct vhost_dev *dev)
     return vhost_kernel_call(dev, VHOST_SET_OWNER, NULL);
 }
 
+static int vhost_kernel_reset_owner(struct vhost_dev *dev)
+{
+    return vhost_kernel_call(dev, VHOST_RESET_OWNER, NULL);
+}
+
 static int vhost_kernel_get_vq_index(struct vhost_dev *dev, int idx)
 {
     assert(idx >= dev->vq_index && idx < dev->vq_index + dev->nvqs);
@@ -385,6 +390,7 @@ const VhostOps kernel_ops = {
         .vhost_get_features_ex = vhost_kernel_get_features,
         .vhost_set_backend_cap = vhost_kernel_set_backend_cap,
         .vhost_set_owner = vhost_kernel_set_owner,
+        .vhost_reset_owner = vhost_kernel_reset_owner,
         .vhost_get_vq_index = vhost_kernel_get_vq_index,
         .vhost_vsock_set_guest_cid = vhost_kernel_vsock_set_guest_cid,
         .vhost_vsock_set_running = vhost_kernel_vsock_set_running,
diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-backend.h
index d878d7b733a..6c949e6a38d 100644
--- a/include/hw/virtio/vhost-backend.h
+++ b/include/hw/virtio/vhost-backend.h
@@ -204,6 +204,7 @@ typedef struct VhostOps {
     vhost_get_features_op vhost_get_features;
     vhost_set_backend_cap_op vhost_set_backend_cap;
     vhost_set_owner_op vhost_set_owner;
+    vhost_set_owner_op vhost_reset_owner;
     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;
-- 
2.47.1