From: Avihai Horon <avihaih@nvidia.com>

Add a flag to VFIOContainerBase that indicates whether dirty tracking
has been started for the container or not.

This will be used in the following patches to allow dirty page syncs
only if dirty tracking has been started.

Signed-off-by: Avihai Horon <avihaih@nvidia.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Tested-by: Joao Martins <joao.m.martins@oracle.com>
Link: https://lore.kernel.org/r/20241218134022.21264-2-avihaih@nvidia.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
 include/hw/vfio/vfio-container-base.h |  1 +
 hw/vfio/container-base.c              | 12 +++++++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/include/hw/vfio/vfio-container-base.h b/include/hw/vfio/vfio-container-base.h
index 62a8b60d87db263225147a21eff2ef6e21cb22df..4cff9943ab4861a25d07b5ebd1200509ebfab12d 100644
--- a/include/hw/vfio/vfio-container-base.h
+++ b/include/hw/vfio/vfio-container-base.h
@@ -44,6 +44,7 @@ typedef struct VFIOContainerBase {
     unsigned long pgsizes;
     unsigned int dma_max_mappings;
     bool dirty_pages_supported;
+    bool dirty_pages_started; /* Protected by BQL */
     QLIST_HEAD(, VFIOGuestIOMMU) giommu_list;
     QLIST_HEAD(, VFIORamDiscardListener) vrdl_list;
     QLIST_ENTRY(VFIOContainerBase) next;
diff --git a/hw/vfio/container-base.c b/hw/vfio/container-base.c
index 6f86c37d971ec38426dacd471bca837c0d0df806..749a3fd29dd6fc9143f14edf7e4ac6238315fcce 100644
--- a/hw/vfio/container-base.c
+++ b/hw/vfio/container-base.c
@@ -64,13 +64,23 @@ int vfio_container_set_dirty_page_tracking(VFIOContainerBase *bcontainer,
                                            bool start, Error **errp)
 {
     VFIOIOMMUClass *vioc = VFIO_IOMMU_GET_CLASS(bcontainer);
+    int ret;
 
     if (!bcontainer->dirty_pages_supported) {
         return 0;
     }
 
     g_assert(vioc->set_dirty_page_tracking);
-    return vioc->set_dirty_page_tracking(bcontainer, start, errp);
+    if (bcontainer->dirty_pages_started == start) {
+        return 0;
+    }
+
+    ret = vioc->set_dirty_page_tracking(bcontainer, start, errp);
+    if (!ret) {
+        bcontainer->dirty_pages_started = start;
+    }
+
+    return ret;
 }
 
 int vfio_container_query_dirty_bitmap(const VFIOContainerBase *bcontainer,
-- 
2.47.1