[v2 1/1] vfio: Change default dirty pages tracking behavior during migration

[Kirti Wankhede]

By default dirty pages tracking is enabled during iterative phase
(pre-copy phase).
Added per device opt-out option 'pre-copy-dirty-page-tracking' to
disable dirty pages tracking during iterative phase. If the option
'pre-copy-dirty-page-tracking=off' is set for any VFIO device, dirty
pages tracking during iterative phase will be disabled.

Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
---
 hw/vfio/common.c              | 11 +++++++----
 hw/vfio/pci.c                 |  3 +++
 include/hw/vfio/vfio-common.h |  1 +
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index c1fdbf17f2e6..6ff1daa763f8 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -311,7 +311,7 @@ bool vfio_mig_active(void)
     return true;
 }
 
-static bool vfio_devices_all_stopped_and_saving(VFIOContainer *container)
+static bool vfio_devices_all_saving(VFIOContainer *container)
 {
     VFIOGroup *group;
     VFIODevice *vbasedev;
@@ -329,8 +329,11 @@ static bool 
vfio_devices_all_stopped_and_saving(VFIOContainer *container)
                 return false;
             }
 
-            if ((migration->device_state & VFIO_DEVICE_STATE_SAVING) &&
-                !(migration->device_state & VFIO_DEVICE_STATE_RUNNING)) {
+            if (migration->device_state & VFIO_DEVICE_STATE_SAVING) {
+                if ((vbasedev->pre_copy_dirty_page_tracking == ON_OFF_AUTO_OFF)
+                    && (migration->device_state & VFIO_DEVICE_STATE_RUNNING)) {
+                        return false;
+                }
                 continue;
             } else {
                 return false;
@@ -1125,7 +1128,7 @@ static void vfio_listerner_log_sync(MemoryListener 
*listener,
         return;
     }
 
-    if (vfio_devices_all_stopped_and_saving(container)) {
+    if (vfio_devices_all_saving(container)) {
         vfio_sync_dirty_bitmap(container, section);
     }
 }
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 58c0ce8971e3..5601df6d6241 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -3182,6 +3182,9 @@ static void vfio_instance_init(Object *obj)
 static Property vfio_pci_dev_properties[] = {
     DEFINE_PROP_PCI_HOST_DEVADDR("host", VFIOPCIDevice, host),
     DEFINE_PROP_STRING("sysfsdev", VFIOPCIDevice, vbasedev.sysfsdev),
+    DEFINE_PROP_ON_OFF_AUTO("x-pre-copy-dirty-page-tracking", VFIOPCIDevice,
+                            vbasedev.pre_copy_dirty_page_tracking,
+                            ON_OFF_AUTO_ON),
     DEFINE_PROP_ON_OFF_AUTO("display", VFIOPCIDevice,
                             display, ON_OFF_AUTO_OFF),
     DEFINE_PROP_UINT32("xres", VFIOPCIDevice, display_xres, 0),
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index baeb4dcff102..267cf854bbba 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -129,6 +129,7 @@ typedef struct VFIODevice {
     unsigned int flags;
     VFIOMigration *migration;
     Error *migration_blocker;
+    OnOffAuto pre_copy_dirty_page_tracking;
 } VFIODevice;
 
 struct VFIODeviceOps {
-- 
2.7.0