[PATCH 4/5] vfio/iommu_type1: Carefully use unmap_unpin_all during dirty tracking

[Keqian Zhu]

If we detach group during dirty page tracking, we shouldn't remove
vfio_dma, because dirty log will lose.

But we don't prevent unmap_unpin_all in vfio_iommu_release, because
under normal procedure, dirty tracking has been stopped.

Fixes: d6a4c185660c ("vfio iommu: Implementation of ioctl for dirty pages tracking")
Signed-off-by: Keqian Zhu <zhukeqian1 at huawei.com>
---
 drivers/vfio/vfio_iommu_type1.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 26b7eb2a5cfc..9776a059904d 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2373,7 +2373,12 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 			if (list_empty(&iommu->external_domain->group_list)) {
 				vfio_sanity_check_pfn_list(iommu);
 
-				if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu))
+				/*
+				 * During dirty page tracking, we can't remove
+				 * vfio_dma because dirty log will lose.
+				 */
+				if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu) &&
+				    !iommu->dirty_page_tracking)
 					vfio_iommu_unmap_unpin_all(iommu);
 
 				kfree(iommu->external_domain);
@@ -2406,10 +2411,15 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 		 * iommu and external domain doesn't exist, then all the
 		 * mappings go away too. If it's the last domain with iommu and
 		 * external domain exist, update accounting
+		 *
+		 * Note: During dirty page tracking, we can't remove vfio_dma
+		 * because dirty log will lose. Just update accounting is a good
+		 * choice.
 		 */
 		if (list_empty(&domain->group_list)) {
 			if (list_is_singular(&iommu->domain_list)) {
-				if (!iommu->external_domain)
+				if (!iommu->external_domain &&
+				    !iommu->dirty_page_tracking)
 					vfio_iommu_unmap_unpin_all(iommu);
 				else
 					vfio_iommu_unmap_unpin_reaccount(iommu);
-- 
2.19.1