linux-kernel - [PATCH 2/4] vfio: selftests: fix map limit tests to use last available iova

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Message-ID: <20251110-iova-ranges-v1-2-4d441cf5bf6d@fb.com>
Date: Mon, 10 Nov 2025 13:10:42 -0800
From: Alex Mastro <amastro@...com>
To: Alex Williamson <alex@...zbot.org>, David Matlack <dmatlack@...gle.com>,
        Shuah Khan <shuah@...nel.org>
CC: <kvm@...r.kernel.org>, <linux-kselftest@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, Alex Mastro <amastro@...com>,
        Jason Gunthorpe
	<jgg@...pe.ca>
Subject: [PATCH 2/4] vfio: selftests: fix map limit tests to use last
 available iova

Use the newly available vfio_pci_iova_ranges() to determine the last
legal IOVA, and use this as the basis for vfio_dma_map_limit_test tests.

Fixes: de8d1f2fd5a5 ("vfio: selftests: add end of address space DMA map/unmap tests")
Signed-off-by: Alex Mastro <amastro@...com>
---
 tools/testing/selftests/vfio/vfio_dma_mapping_test.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/vfio/vfio_dma_mapping_test.c b/tools/testing/selftests/vfio/vfio_dma_mapping_test.c
index 4f1ea79a200c..37c2a342df8d 100644
--- a/tools/testing/selftests/vfio/vfio_dma_mapping_test.c
+++ b/tools/testing/selftests/vfio/vfio_dma_mapping_test.c
@@ -3,6 +3,8 @@
 #include <sys/mman.h>
 #include <unistd.h>
 
+#include <uapi/linux/types.h>
+#include <linux/iommufd.h>
 #include <linux/limits.h>
 #include <linux/mman.h>
 #include <linux/sizes.h>
@@ -219,7 +221,10 @@ FIXTURE_VARIANT_ADD_ALL_IOMMU_MODES();
 FIXTURE_SETUP(vfio_dma_map_limit_test)
 {
 	struct vfio_dma_region *region = &self->region;
+	struct iommu_iova_range *ranges;
 	u64 region_size = getpagesize();
+	iova_t last_iova;
+	size_t nranges;
 
 	/*
 	 * Over-allocate mmap by double the size to provide enough backing vaddr
@@ -232,8 +237,13 @@ FIXTURE_SETUP(vfio_dma_map_limit_test)
 			     MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
 	ASSERT_NE(region->vaddr, MAP_FAILED);
 
-	/* One page prior to the end of address space */
-	region->iova = ~(iova_t)0 & ~(region_size - 1);
+	ranges = vfio_pci_iova_ranges(self->device, &nranges);
+	VFIO_ASSERT_NOT_NULL(ranges);
+	last_iova = ranges[nranges - 1].last;
+	free(ranges);
+
+	/* One page prior to the last iova */
+	region->iova = last_iova & ~(region_size - 1);
 	region->size = region_size;
 }
 
@@ -276,6 +286,9 @@ TEST_F(vfio_dma_map_limit_test, overflow)
 	struct vfio_dma_region *region = &self->region;
 	int rc;
 
+	if (region->iova != (~(iova_t)0 & ~(region->size - 1)))
+		SKIP(return, "IOMMU address space insufficient for overflow test");
+
 	region->size = self->mmap_size;
 
 	rc = __vfio_pci_dma_map(self->device, region);

-- 
2.47.3