[RFC V1 04/13] vhost-vdpa: VHOST_BACKEND_F_NEW_OWNER

[Steve Sistare]

Add the VHOST_BACKEND_F_NEW_OWNER backend capability, which indicates that
VHOST_NEW_OWNER is supported.

Signed-off-by: Steve Sistare <steven.sistare@xxxxxxxxxx>
---
 drivers/vhost/vdpa.c             | 7 ++++++-
 include/uapi/linux/vhost_types.h | 2 ++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index eb3a95e703b0..faed6471934a 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -621,6 +621,10 @@ static long vhost_vdpa_new_owner(struct vhost_vdpa *v)
 	struct mm_struct *mm_new = current->mm;
 	long pinned_vm = v->pinned_vm;
 	unsigned long lock_limit = PFN_DOWN(rlimit(RLIMIT_MEMLOCK));
+	u64 features = vhost_vdpa_get_backend_features(v);
+
+	if (!(features & BIT_ULL(VHOST_BACKEND_F_NEW_OWNER)))
+		return -EOPNOTSUPP;
 
 	if (!mm_old)
 		return -EINVAL;
@@ -784,7 +788,8 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
 				 BIT_ULL(VHOST_BACKEND_F_IOTLB_PERSIST) |
 				 BIT_ULL(VHOST_BACKEND_F_SUSPEND) |
 				 BIT_ULL(VHOST_BACKEND_F_RESUME) |
-				 BIT_ULL(VHOST_BACKEND_F_ENABLE_AFTER_DRIVER_OK)))
+				 BIT_ULL(VHOST_BACKEND_F_ENABLE_AFTER_DRIVER_OK) |
+				 BIT_ULL(VHOST_BACKEND_F_NEW_OWNER)))
 			return -EOPNOTSUPP;
 		if ((features & BIT_ULL(VHOST_BACKEND_F_SUSPEND)) &&
 		     !vhost_vdpa_can_suspend(v))
diff --git a/include/uapi/linux/vhost_types.h b/include/uapi/linux/vhost_types.h
index d7656908f730..9177843951e9 100644
--- a/include/uapi/linux/vhost_types.h
+++ b/include/uapi/linux/vhost_types.h
@@ -192,5 +192,7 @@ struct vhost_vdpa_iova_range {
 #define VHOST_BACKEND_F_DESC_ASID    0x7
 /* IOTLB don't flush memory mapping across device reset */
 #define VHOST_BACKEND_F_IOTLB_PERSIST  0x8
+/* Supports VHOST_NEW_OWNER */
+#define VHOST_BACKEND_F_NEW_OWNER  0x9
 
 #endif
-- 
2.39.3