[PATCH] iommu/io-pgtable-arm: Remove iommu_dev==NULL special case

[PATCH] iommu/io-pgtable-arm: Remove iommu_dev==NULL special case

[Robin Murphy]

The special case to allow iommu_dev==NULL in __arm_lpae_alloc_pages() is
confusing to static checkers (and possibly readers in general), since
it's not obvious that that is only intended for the selftests. However
it only serves to get around the dev_to_node() call, and we can easily
fake up enough to make that work anyway, so let's simply remove this
consideration from the normal flow and punt the responsibility over to
the test harness itself.

Reported-by: Rustam Subkhankulov <subkhankulov@ispras.ru>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
 drivers/iommu/io-pgtable-arm.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index 94ff319ae8ac..873a92bbd80c 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -200,8 +200,7 @@ static void *__arm_lpae_alloc_pages(size_t size, gfp_t gfp,
 	void *pages;
 
 	VM_BUG_ON((gfp & __GFP_HIGHMEM));
-	p = alloc_pages_node(dev ? dev_to_node(dev) : NUMA_NO_NODE,
-			     gfp | __GFP_ZERO, order);
+	p = alloc_pages_node(dev_to_node(dev), gfp | __GFP_ZERO, order);
 	if (!p)
 		return NULL;
 
@@ -1343,12 +1342,17 @@ static int __init arm_lpae_do_selftests(void)
 	};
 
 	int i, j, pass = 0, fail = 0;
+	struct device dev;
 	struct io_pgtable_cfg cfg = {
 		.tlb = &dummy_tlb_ops,
 		.oas = 48,
 		.coherent_walk = true,
+		.iommu_dev = &dev,
 	};
 
+	/* __arm_lpae_alloc_pages() merely needs dev_to_node() to work */
+	set_dev_node(&dev, NUMA_NO_NODE);
+
 	for (i = 0; i < ARRAY_SIZE(pgsize); ++i) {
 		for (j = 0; j < ARRAY_SIZE(ias); ++j) {
 			cfg.pgsize_bitmap = pgsize[i];
-- 
2.36.1.dirty

Re: [PATCH] iommu/io-pgtable-arm: Remove iommu_dev==NULL special case

[Joerg Roedel]

On Mon, Aug 15, 2022 at 05:15:55PM +0100, Robin Murphy wrote:
> The special case to allow iommu_dev==NULL in __arm_lpae_alloc_pages() is
> confusing to static checkers (and possibly readers in general), since
> it's not obvious that that is only intended for the selftests. However
> it only serves to get around the dev_to_node() call, and we can easily
> fake up enough to make that work anyway, so let's simply remove this
> consideration from the normal flow and punt the responsibility over to
> the test harness itself.
> 
> Reported-by: Rustam Subkhankulov <subkhankulov@ispras.ru>
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>

Applied, thanks.