[PULL 3/3] vfio/migration: Correct device state from vmstate change for savevm case

[Alex Williamson <alex.williamson@redhat.com>]

From: Kirti Wankhede <kwankhede@nvidia.com>

Set _SAVING flag for device state from vmstate change handler when it
gets called from savevm.

Currently State transition savevm/suspend is seen as:
    _RUNNING -> _STOP -> Stop-and-copy -> _STOP

State transition savevm/suspend should be:
    _RUNNING -> Stop-and-copy -> _STOP

State transition from _RUNNING to _STOP occurs from
vfio_vmstate_change() where when vmstate changes from running to
!running, _RUNNING flag is reset but at the same time when
vfio_vmstate_change() is called for RUN_STATE_SAVE_VM, _SAVING bit
should be set.

Reported by: Yishai Hadas <yishaih@nvidia.com>
Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Message-Id: <1623177441-27496-1-git-send-email-kwankhede@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---
 hw/vfio/migration.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index ef397ebe6c09..82f654afb64a 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -724,7 +724,16 @@ static void vfio_vmstate_change(void *opaque, bool running, RunState state)
          * _RUNNING bit
          */
         mask = ~VFIO_DEVICE_STATE_RUNNING;
-        value = 0;
+
+        /*
+         * When VM state transition to stop for savevm command, device should
+         * start saving data.
+         */
+        if (state == RUN_STATE_SAVE_VM) {
+            value = VFIO_DEVICE_STATE_SAVING;
+        } else {
+            value = 0;
+        }
     }
 
     ret = vfio_migration_set_state(vbasedev, mask, value);