[qemu-xen stable-4.13] virtio: new post_load hook

[patchbot@xxxxxxx]

commit 8010d3fce008dd13f155bc0babfe236ea44a2712
Author:     Michael S. Tsirkin <mst@xxxxxxxxxx>
AuthorDate: Fri Oct 11 15:58:03 2019 +0200
Commit:     Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
CommitDate: Mon Nov 4 08:23:53 2019 -0600

    virtio: new post_load hook
    
    Post load hook in virtio vmsd is called early while device is processed,
    and when VirtIODevice core isn't fully initialized.  Most device
    specific code isn't ready to deal with a device in such state, and
    behaves weirdly.
    
    Add a new post_load hook in a device class instead.  Devices should use
    this unless they specifically want to verify the migration stream as
    it's processed, e.g. for bounds checking.
    
    Cc: qemu-stable@xxxxxxxxxx
    Suggested-by: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx>
    Cc: Mikhail Sennikovsky <mikhail.sennikovskii@xxxxxxxxxxxxxxx>
    Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
    Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
    (cherry picked from commit 1dd713837cac8ec5a97d3b8492d72ce5ac94803c)
    Signed-off-by: Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
---
 hw/virtio/virtio.c         | 7 +++++++
 include/hw/virtio/virtio.h | 6 ++++++
 2 files changed, 13 insertions(+)

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index a94ea18a9c..7c3822c3a0 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -2287,6 +2287,13 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f, int 
version_id)
     }
     rcu_read_unlock();
 
+    if (vdc->post_load) {
+        ret = vdc->post_load(vdev);
+        if (ret) {
+            return ret;
+        }
+    }
+
     return 0;
 }
 
diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index b189788cb2..f9f62370e9 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -158,6 +158,12 @@ typedef struct VirtioDeviceClass {
      */
     void (*save)(VirtIODevice *vdev, QEMUFile *f);
     int (*load)(VirtIODevice *vdev, QEMUFile *f, int version_id);
+    /* Post load hook in vmsd is called early while device is processed, and
+     * when VirtIODevice isn't fully initialized.  Devices should use this 
instead,
+     * unless they specifically want to verify the migration stream as it's
+     * processed, e.g. for bounds checking.
+     */
+    int (*post_load)(VirtIODevice *vdev);
     const VMStateDescription *vmsd;
 } VirtioDeviceClass;
 
--
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