Patch "vfio/iommu_type1: Fix some sanity checks in detach group" has been added to the 5.11-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    vfio/iommu_type1: Fix some sanity checks in detach group

to the 5.11-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     vfio-iommu_type1-fix-some-sanity-checks-in-detach-gr.patch
and it can be found in the queue-5.11 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit fed96b6c02b2196c8a647443a8cd47d6ffe2a91c
Author: Keqian Zhu <zhukeqian1@xxxxxxxxxx>
Date:   Fri Jan 22 17:26:35 2021 +0800

    vfio/iommu_type1: Fix some sanity checks in detach group
    
    [ Upstream commit 4a19f37a3dd3f29997735e61b25ddad24b8abe73 ]
    
    vfio_sanity_check_pfn_list() is used to check whether pfn_list and
    notifier are empty when remove the external domain, so it makes a
    wrong assumption that only external domain will use the pinning
    interface.
    
    Now we apply the pfn_list check when a vfio_dma is removed and apply
    the notifier check when all domains are removed.
    
    Fixes: a54eb55045ae ("vfio iommu type1: Add support for mediated devices")
    Signed-off-by: Keqian Zhu <zhukeqian1@xxxxxxxxxx>
    Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 161725395f2fb..78bd28873945a 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -957,6 +957,7 @@ static long vfio_unmap_unpin(struct vfio_iommu *iommu, struct vfio_dma *dma,
 
 static void vfio_remove_dma(struct vfio_iommu *iommu, struct vfio_dma *dma)
 {
+	WARN_ON(!RB_EMPTY_ROOT(&dma->pfn_list));
 	vfio_unmap_unpin(iommu, dma, true);
 	vfio_unlink_dma(iommu, dma);
 	put_task_struct(dma->task);
@@ -2250,23 +2251,6 @@ static void vfio_iommu_unmap_unpin_reaccount(struct vfio_iommu *iommu)
 	}
 }
 
-static void vfio_sanity_check_pfn_list(struct vfio_iommu *iommu)
-{
-	struct rb_node *n;
-
-	n = rb_first(&iommu->dma_list);
-	for (; n; n = rb_next(n)) {
-		struct vfio_dma *dma;
-
-		dma = rb_entry(n, struct vfio_dma, node);
-
-		if (WARN_ON(!RB_EMPTY_ROOT(&dma->pfn_list)))
-			break;
-	}
-	/* mdev vendor driver must unregister notifier */
-	WARN_ON(iommu->notifier.head);
-}
-
 /*
  * Called when a domain is removed in detach. It is possible that
  * the removed domain decided the iova aperture window. Modify the
@@ -2366,10 +2350,10 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 			kfree(group);
 
 			if (list_empty(&iommu->external_domain->group_list)) {
-				vfio_sanity_check_pfn_list(iommu);
-
-				if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu))
+				if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)) {
+					WARN_ON(iommu->notifier.head);
 					vfio_iommu_unmap_unpin_all(iommu);
+				}
 
 				kfree(iommu->external_domain);
 				iommu->external_domain = NULL;
@@ -2403,10 +2387,12 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 		 */
 		if (list_empty(&domain->group_list)) {
 			if (list_is_singular(&iommu->domain_list)) {
-				if (!iommu->external_domain)
+				if (!iommu->external_domain) {
+					WARN_ON(iommu->notifier.head);
 					vfio_iommu_unmap_unpin_all(iommu);
-				else
+				} else {
 					vfio_iommu_unmap_unpin_reaccount(iommu);
+				}
 			}
 			iommu_domain_free(domain->domain);
 			list_del(&domain->next);
@@ -2490,7 +2476,6 @@ static void vfio_iommu_type1_release(void *iommu_data)
 
 	if (iommu->external_domain) {
 		vfio_release_domain(iommu->external_domain, true);
-		vfio_sanity_check_pfn_list(iommu);
 		kfree(iommu->external_domain);
 	}