[PATCH v3 12/13] vfio/migration: Query device dirty page tracking support

[Joao Martins]

Now that everything has been set up for device dirty page tracking,
query the device for device dirty page tracking support.

Signed-off-by: Avihai Horon <avihaih@nvidia.com>
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
---
 hw/vfio/migration.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index 3e75868ae7a9..da3aa596b3ec 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -555,6 +555,19 @@ static int vfio_migration_query_flags(VFIODevice 
*vbasedev, uint64_t *mig_flags)
     return 0;
 }
 
+static bool vfio_dma_logging_supported(VFIODevice *vbasedev)
+{
+    uint64_t buf[DIV_ROUND_UP(sizeof(struct vfio_device_feature),
+                              sizeof(uint64_t))] = {};
+    struct vfio_device_feature *feature = (struct vfio_device_feature *)buf;
+
+    feature->argsz = sizeof(buf);
+    feature->flags =
+        VFIO_DEVICE_FEATURE_PROBE | VFIO_DEVICE_FEATURE_DMA_LOGGING_START;
+
+    return !ioctl(vbasedev->fd, VFIO_DEVICE_FEATURE, feature);
+}
+
 static int vfio_migration_init(VFIODevice *vbasedev)
 {
     int ret;
@@ -589,6 +602,8 @@ static int vfio_migration_init(VFIODevice *vbasedev)
     migration->device_state = VFIO_DEVICE_STATE_RUNNING;
     migration->data_fd = -1;
 
+    vbasedev->dirty_pages_supported = vfio_dma_logging_supported(vbasedev);
+
     oid = vmstate_if_get_id(VMSTATE_IF(DEVICE(obj)));
     if (oid) {
         path = g_strdup_printf("%s/vfio", oid);
-- 
2.17.2