diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-backend.h
index 00881a0bd4..d878d7b733 100644
--- a/include/hw/virtio/vhost-backend.h
+++ b/include/hw/virtio/vhost-backend.h
@@ -162,6 +162,15 @@ typedef int (*vhost_set_device_state_fd_op)(struct vhost_dev *dev,
                                             int *reply_fd,
                                             Error **errp);
 typedef int (*vhost_check_device_state_op)(struct vhost_dev *dev, Error **errp);
+/*
+ * Max regions is VIRTIO_MAX_SHMEM_REGIONS, so that is the maximum
+ * number of memory_sizes that will be accepted.
+ */
+typedef int (*vhost_get_shmem_config_op)(struct vhost_dev *dev,
+                                         int *nregions,
+                                         uint64_t *memory_sizes,
+                                         Error **errp);
+
 
 typedef struct VhostOps {
     VhostBackendType backend_type;
@@ -220,6 +229,7 @@ typedef struct VhostOps {
     vhost_supports_device_state_op vhost_supports_device_state;
     vhost_set_device_state_fd_op vhost_set_device_state_fd;
     vhost_check_device_state_op vhost_check_device_state;
+    vhost_get_shmem_config_op vhost_get_shmem_config;
 } VhostOps;
 
 int vhost_user_gpu_set_socket(struct vhost_dev *dev, int fd);
diff --git a/include/hw/virtio/vhost-user.h b/include/hw/virtio/vhost-user.h
index 5ab70dab7e..06c360af18 100644
--- a/include/hw/virtio/vhost-user.h
+++ b/include/hw/virtio/vhost-user.h
@@ -35,6 +35,7 @@ enum VhostUserProtocolFeature {
     VHOST_USER_PROTOCOL_F_DEVICE_STATE = 19,
     VHOST_USER_PROTOCOL_F_GET_VRING_BASE_INFLIGHT = 20,
     VHOST_USER_PROTOCOL_F_GPA_ADDRESSES = 21,
+    VHOST_USER_PROTOCOL_F_SHMEM = 22,
     VHOST_USER_PROTOCOL_F_MAX
 };
 
diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index 3f745e3b67..c99cb19d88 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -82,6 +82,8 @@ typedef struct VirtQueueElement
 
 #define VIRTIO_NO_VECTOR 0xffff
 
+#define VIRTIO_MAX_SHMEM_REGIONS 256
+
 /* special index value used internally for config irqs */
 #define VIRTIO_CONFIG_IRQ_IDX -1
 
diff --git a/subprojects/libvhost-user/libvhost-user.h b/subprojects/libvhost-user/libvhost-user.h
index 6a2d0f9fae..a534d70771 100644
--- a/subprojects/libvhost-user/libvhost-user.h
+++ b/subprojects/libvhost-user/libvhost-user.h
@@ -70,7 +70,9 @@ enum VhostUserProtocolFeature {
     /* Feature 17 reserved for VHOST_USER_PROTOCOL_F_XEN_MMAP. */
     VHOST_USER_PROTOCOL_F_SHARED_OBJECT = 18,
     /* Feature 19 is reserved for VHOST_USER_PROTOCOL_F_DEVICE_STATE */
-    VHOST_USER_PROTOCOL_F_SHMEM = 20,
+    /* Feature 20 is reserved for VHOST_USER_PROTOCOL_F_GET_VRING_BASE_INFLIGHT */
+    /* Feature 21 is reserved for VHOST_USER_PROTOCOL_F_GPA_ADDRESSES */
+    VHOST_USER_PROTOCOL_F_SHMEM = 22,
     VHOST_USER_PROTOCOL_F_MAX
 };