[PATCH 14/19] iommu/pages: Move the __GFP_HIGHMEM checks into the common code

[Jason Gunthorpe]

The entire allocator API is built around using the kernel virtual address,
it is illegal to pass GFP_HIGHMEM in as a GFP flag. Block it in the common
code. Remove the duplicated checks from drivers.

Signed-off-by: Jason Gunthorpe <jgg at nvidia.com>
---
 drivers/iommu/io-pgtable-arm.c  | 2 --
 drivers/iommu/io-pgtable-dart.c | 1 -
 drivers/iommu/iommu-pages.c     | 4 ++++
 3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index b4c3729076376b..8727d8e1e02f45 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -267,8 +267,6 @@ static void *__arm_lpae_alloc_pages(size_t size, gfp_t gfp,
 	dma_addr_t dma;
 	void *pages;
 
-	VM_BUG_ON((gfp & __GFP_HIGHMEM));
-
 	if (cfg->alloc)
 		pages = cfg->alloc(cookie, size, gfp);
 	else
diff --git a/drivers/iommu/io-pgtable-dart.c b/drivers/iommu/io-pgtable-dart.c
index f7b939d4b7d0b9..a4cbd8a8a2976e 100644
--- a/drivers/iommu/io-pgtable-dart.c
+++ b/drivers/iommu/io-pgtable-dart.c
@@ -111,7 +111,6 @@ static void *__dart_alloc_pages(size_t size, gfp_t gfp)
 {
 	int order = get_order(size);
 
-	VM_BUG_ON((gfp & __GFP_HIGHMEM));
 	return iommu_alloc_pages(gfp, order);
 }
 
diff --git a/drivers/iommu/iommu-pages.c b/drivers/iommu/iommu-pages.c
index f7def716997af4..47ee9ad4a40d4d 100644
--- a/drivers/iommu/iommu-pages.c
+++ b/drivers/iommu/iommu-pages.c
@@ -37,6 +37,10 @@ void *iommu_alloc_pages_node(int nid, gfp_t gfp, unsigned int order)
 	const unsigned long pgcnt = 1UL << order;
 	struct folio *folio;
 
+	/* This uses page_address() on the memory. */
+	if (WARN_ON(gfp & __GFP_HIGHMEM))
+		return NULL;
+
 	/*
 	 * __folio_alloc_node() does not handle NUMA_NO_NODE like
 	 * alloc_pages_node() did.
-- 
2.43.0