[RFC PATCH v2 2/4] vfio: Add vfio_prereg_listener_log_sync in nested stage

[Kunkun Jiang]

On Intel, the DMA mapped through the host single stage. Instead
we set up the stage 2 and stage 1 separately in nested mode as there
is no "Caching Mode".

Legacy vfio_listener_log_sync cannot be used in nested stage as we
don't need to pay close attention to stage 1 mapping. This patch adds
vfio_prereg_listener_log_sync to mark dirty pages in nested mode.

Signed-off-by: Kunkun Jiang <jiangkunkun@huawei.com>
---
 hw/vfio/common.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 3117979307..86722814d4 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -1284,6 +1284,22 @@ static int 
vfio_dma_sync_ram_section_dirty_bitmap(VFIOContainer *container,
                     int128_get64(section->size), ram_addr);
 }
 
+static void vfio_prereg_listener_log_sync(MemoryListener *listener,
+                                          MemoryRegionSection *section)
+{
+    VFIOContainer *container =
+        container_of(listener, VFIOContainer, prereg_listener);
+
+    if (!memory_region_is_ram(section->mr) ||
+        !container->dirty_pages_supported) {
+        return;
+    }
+
+    if (vfio_devices_all_dirty_tracking(container)) {
+        vfio_dma_sync_ram_section_dirty_bitmap(container, section);
+    }
+}
+
 typedef struct {
     IOMMUNotifier n;
     VFIOGuestIOMMU *giommu;
@@ -1328,6 +1344,16 @@ static int vfio_sync_dirty_bitmap(VFIOContainer 
*container,
     if (memory_region_is_iommu(section->mr)) {
         VFIOGuestIOMMU *giommu;
 
+        /*
+         * In nested mode, stage 2 (gpa->hpa) and stage 1 (giova->gpa) are
+         * set up separately. It is inappropriate to pass 'giova' to kernel
+         * to get dirty pages. We only need to focus on stage 2 mapping when
+         * marking dirty pages.
+         */
+        if (container->iommu_type == VFIO_TYPE1_NESTING_IOMMU) {
+            return 0;
+        }
+
         QLIST_FOREACH(giommu, &container->giommu_list, giommu_next) {
             if (MEMORY_REGION(giommu->iommu) == section->mr &&
                 giommu->n.start == section->offset_within_region) {
@@ -1382,6 +1408,7 @@ static const MemoryListener vfio_memory_listener = {
 static MemoryListener vfio_memory_prereg_listener = {
     .region_add = vfio_prereg_listener_region_add,
     .region_del = vfio_prereg_listener_region_del,
+    .log_sync = vfio_prereg_listener_log_sync,
 };
 
 static void vfio_listener_release(VFIOContainer *container)
-- 
2.23.0