vdpa: move iotlb_batch_begin_sent to vhost_vdpa_shared

Next patches will register the vhost_vdpa memory listener while the VM
is migrating at the destination, so we can map the memory to the device
before stopping the VM at the source.  The main goal is to reduce the
downtime.

However, the destination QEMU is unaware of which vhost_vdpa device will
register its memory_listener.  If the source guest has CVQ enabled, it
will be the CVQ device.  Otherwise, it  will be the first one.

Move the iotlb_batch_begin_sent member to VhostVDPAShared so all
vhost_vdpa can use it, rather than always in the first / last
vhost_vdpa.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20231221174322.3130442-8-eperezma@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/virtio/vhost-vdpa.c

@@ -162,11 +162,11 @@ static void vhost_vdpa_listener_begin_batch(struct vhost_vdpa *v)
 static void vhost_vdpa_iotlb_batch_begin_once(struct vhost_vdpa *v)
 {
     if (v->dev->backend_cap & (0x1ULL << VHOST_BACKEND_F_IOTLB_BATCH) &&
-        !v->iotlb_batch_begin_sent) {
+        !v->shared->iotlb_batch_begin_sent) {
         vhost_vdpa_listener_begin_batch(v);
     }
 
-    v->iotlb_batch_begin_sent = true;
+    v->shared->iotlb_batch_begin_sent = true;
 }
 
 static void vhost_vdpa_listener_commit(MemoryListener *listener)
@@ -180,7 +180,7 @@ static void vhost_vdpa_listener_commit(MemoryListener *listener)
         return;
     }
 
-    if (!v->iotlb_batch_begin_sent) {
+    if (!v->shared->iotlb_batch_begin_sent) {
         return;
     }
 
@@ -193,7 +193,7 @@ static void vhost_vdpa_listener_commit(MemoryListener *listener)
                      fd, errno, strerror(errno));
     }
 
-    v->iotlb_batch_begin_sent = false;
+    v->shared->iotlb_batch_begin_sent = false;
 }
 
 static void vhost_vdpa_iommu_map_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb)

include/hw/virtio/vhost-vdpa.h

@@ -38,14 +38,15 @@ typedef struct vhost_vdpa_shared {
     /* IOVA mapping used by the Shadow Virtqueue */
     VhostIOVATree *iova_tree;
 
+    bool iotlb_batch_begin_sent;
+
     /* Vdpa must send shadow addresses as IOTLB key for data queues, not GPA */
     bool shadow_data;
 } VhostVDPAShared;
 
 typedef struct vhost_vdpa {
     int index;
     uint32_t msg_type;
-    bool iotlb_batch_begin_sent;
     uint32_t address_space_id;
     MemoryListener listener;
     uint64_t acked_features;