RE: [PATCH v3 09/10] vfio/migration: Don't block migration device dirty tracking is unsupported

[Duan, Zhenzhong]

>-----Original Message-----
>From: Joao Martins <joao.m.martins@oracle.com>
>Subject: [PATCH v3 09/10] vfio/migration: Don't block migration device dirty
>tracking is unsupported
>
>By default VFIO migration is set to auto, which will support live
>migration if the migration capability is set *and* also dirty page
>tracking is supported.
>
>For testing purposes one can force enable without dirty page tracking
>via enable-migration=on, but that option is generally left for testing
>purposes.
>
>So starting with IOMMU dirty tracking it can use to acomodate the lack of
>VF dirty page tracking allowing us to minimize the VF requirements for
>migration and thus enabling migration by default for those.
>
>Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
>---
> hw/vfio/migration.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
>diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
>index 34d4be2ce1b1..89195928666f 100644
>--- a/hw/vfio/migration.c
>+++ b/hw/vfio/migration.c
>@@ -1012,6 +1012,7 @@ void vfio_reset_bytes_transferred(void)
>  */
> bool vfio_migration_realize(VFIODevice *vbasedev, Error **errp)
> {
>+    HostIOMMUDeviceClass *hiodc =
>HOST_IOMMU_DEVICE_GET_CLASS(vbasedev->hiod);
>     Error *err = NULL;
>     int ret;
>
>@@ -1036,7 +1037,10 @@ bool vfio_migration_realize(VFIODevice
>*vbasedev, Error **errp)
>         return !vfio_block_migration(vbasedev, err, errp);
>     }
>
>-    if (!vbasedev->dirty_pages_supported) {
>+    if (!vbasedev->dirty_pages_supported &&
>+        (vbasedev->iommufd &&
>+         !hiodc->get_cap(vbasedev->hiod,
>+                         HOST_IOMMU_DEVICE_CAP_DIRTY_TRACKING, NULL))) {

What about below, this can avoid a new CAP define.

--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -1036,7 +1036,7 @@ bool vfio_migration_realize(VFIODevice *vbasedev, Error 
**errp)
         return !vfio_block_migration(vbasedev, err, errp);
     }

-    if (!vbasedev->dirty_pages_supported) {
+    if (!vbasedev->dirty_pages_supported && 
!vbasedev->bcontainer->dirty_pages_supported) {
         if (vbasedev->enable_migration == ON_OFF_AUTO_AUTO) {
             error_setg(&err,
                        "%s: VFIO device doesn't support device dirty tracking",

Thanks
Zhenzhong

>         if (vbasedev->enable_migration == ON_OFF_AUTO_AUTO) {
>             error_setg(&err,
>                        "%s: VFIO device doesn't support device dirty 
> tracking",
>--
>2.17.2