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 <avih...@nvidia.com>
Reviewed-by: Joao Martins <joao.m.mart...@oracle.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 62a8b60d87..4cff9943ab 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 6f86c37d97..749a3fd29d 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,
-- 
2.40.1


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