[PATCH rc 2/5] iommu: Fix up map/unmap debugging for iommupt domains

[Jason Gunthorpe <jgg@nvidia.com>]

Sashiko noticed a few issues in this path, and a few more were
found on review. Tidy them up further. These are intertwined
because the debug code depends on some of the WARN_ONs to function
right:

Lift into iommu_map_nosync():
- The might_sleep_if()
- 0 pgsize_bitmap WARN_ON
- Promote the illegal domain->type to a WARN_ON
- WARN_ON for illegal gfp flags

Then remove the return 0 since it is now safe to call
iommu_debug_map().

Lift into __iommu_unmap():
- 0 pgsize_bitmap WARN_ON
- Promote the illegal domain->type to a WARN_ON
- iommu_debug_unmap_begin()

This now pairs with the unconditional iommu_debug_map() on the
mapping side. Thus iommu debugging now works for iommupt along
with some of the other debugging features.

Fixes: 99fb8afa16ad ("iommupt: Directly call iommupt's unmap_range()")
Fixes: d6c65b0fd621 ("iommupt: Avoid rewalking during map")
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
 drivers/iommu/iommu.c | 43 ++++++++++++++++++++++---------------------
 1 file changed, 22 insertions(+), 21 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 6e53cfad5dc001..e334588a2476b4 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2583,19 +2583,9 @@ static int __iommu_map_domain_pgtbl(struct iommu_domain *domain,
 	size_t orig_size = size;
 	int ret = 0;
 
-	might_sleep_if(gfpflags_allow_blocking(gfp));
-
-	if (unlikely(!(domain->type & __IOMMU_DOMAIN_PAGING)))
-		return -EINVAL;
-
-	if (WARN_ON(!ops->map_pages || domain->pgsize_bitmap == 0UL))
+	if (WARN_ON(!ops->map_pages))
 		return -ENODEV;
 
-	/* Discourage passing strange GFP flags */
-	if (WARN_ON_ONCE(gfp & (__GFP_COMP | __GFP_DMA | __GFP_DMA32 |
-				__GFP_HIGHMEM)))
-		return -EINVAL;
-
 	/* find out the minimum page size supported */
 	min_pagesz = 1 << __ffs(domain->pgsize_bitmap);
 
@@ -2657,6 +2647,15 @@ int iommu_map_nosync(struct iommu_domain *domain, unsigned long iova,
 	struct pt_iommu *pt = iommupt_from_domain(domain);
 	int ret;
 
+	might_sleep_if(gfpflags_allow_blocking(gfp));
+
+	/* Discourage passing strange GFP flags or illegal domains */
+	if (WARN_ON_ONCE(!(domain->type & __IOMMU_DOMAIN_PAGING) ||
+			 !domain->pgsize_bitmap ||
+			 (gfp & (__GFP_COMP | __GFP_DMA | __GFP_DMA32 |
+				 __GFP_HIGHMEM))))
+		return -EINVAL;
+
 	if (pt) {
 		size_t mapped = 0;
 
@@ -2666,11 +2665,12 @@ int iommu_map_nosync(struct iommu_domain *domain, unsigned long iova,
 			iommu_unmap(domain, iova, mapped);
 			return ret;
 		}
-		return 0;
+	} else {
+		ret = __iommu_map_domain_pgtbl(domain, iova, paddr, size, prot,
+					       gfp);
+		if (ret)
+			return ret;
 	}
-	ret = __iommu_map_domain_pgtbl(domain, iova, paddr, size, prot, gfp);
-	if (ret)
-		return ret;
 
 	trace_map(iova, paddr, size);
 	iommu_debug_map(domain, paddr, size);
@@ -2702,10 +2702,7 @@ __iommu_unmap_domain_pgtbl(struct iommu_domain *domain, unsigned long iova,
 	size_t unmapped_page, unmapped = 0;
 	unsigned int min_pagesz;
 
-	if (unlikely(!(domain->type & __IOMMU_DOMAIN_PAGING)))
-		return 0;
-
-	if (WARN_ON(!ops->unmap_pages || domain->pgsize_bitmap == 0UL))
+	if (WARN_ON(!ops->unmap_pages))
 		return 0;
 
 	/* find out the minimum page size supported */
@@ -2724,8 +2721,6 @@ __iommu_unmap_domain_pgtbl(struct iommu_domain *domain, unsigned long iova,
 
 	pr_debug("unmap this: iova 0x%lx size 0x%zx\n", iova, size);
 
-	iommu_debug_unmap_begin(domain, iova, size);
-
 	/*
 	 * Keep iterating until we either unmap 'size' bytes (or more)
 	 * or we hit an area that isn't mapped.
@@ -2761,6 +2756,12 @@ static size_t __iommu_unmap(struct iommu_domain *domain, unsigned long iova,
 	struct pt_iommu *pt = iommupt_from_domain(domain);
 	size_t unmapped;
 
+	if (WARN_ON_ONCE(!(domain->type & __IOMMU_DOMAIN_PAGING) ||
+			 !domain->pgsize_bitmap))
+		return 0;
+
+	iommu_debug_unmap_begin(domain, iova, size);
+
 	if (pt)
 		unmapped = pt->ops->unmap_range(pt, iova, size, iotlb_gather);
 	else
-- 
2.43.0