[PATCH v8 10/15] iommupt: Add a mock pagetable format for iommufd selftest to use

Jason Gunthorpe
2025-11-04T18:30:34Z

The iommufd self test uses an xarray to store the pfns and their orders to
emulate a page table. Slightly modify the amdv1 page table to create a
real page table that has similar properties:

- 2k base granule to simulate something like a 4k page table on a 64K
PAGE_SIZE ARM system
- Contiguous page support for every PFN order
- Dirty tracking

AMDv1 is the closest format, as it is the only one that already supports
every page size. Tweak it to have only 5 levels and an 11 bit base granule
and compile it separately as a format variant.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Samiullah Khawaja <skhawaja@google.com>
Tested-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Tested-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
drivers/iommu/generic_pt/fmt/Makefile | 1 +
drivers/iommu/generic_pt/fmt/amdv1.h | 18 ++++++++++++++++--
drivers/iommu/generic_pt/fmt/iommu_mock.c | 10 ++++++++++
include/linux/generic_pt/iommu.h | 6 ++++++
4 files changed, 33 insertions(+), 2 deletions(-)
create mode 100644 drivers/iommu/generic_pt/fmt/iommu_mock.c

diff --git a/drivers/iommu/generic_pt/fmt/Makefile b/drivers/iommu/generic_pt/fmt/Makefile
index 32f3956c7509f8..f0c22cf5f7bee6 100644
--- a/drivers/iommu/generic_pt/fmt/Makefile
+++ b/drivers/iommu/generic_pt/fmt/Makefile
@@ -1,6 +1,7 @@
# SPDX-License-Identifier: GPL-2.0

iommu_pt_fmt-$(CONFIG_IOMMU_PT_AMDV1) += amdv1
+iommu_pt_fmt-$(CONFIG_IOMMUFD_TEST) += mock

IOMMU_PT_KUNIT_TEST :=
define create_format
diff --git a/drivers/iommu/generic_pt/fmt/amdv1.h b/drivers/iommu/generic_pt/fmt/amdv1.h
index aaf76bfd21dadc..aa8e1a8ec95fde 100644
--- a/drivers/iommu/generic_pt/fmt/amdv1.h
+++ b/drivers/iommu/generic_pt/fmt/amdv1.h
@@ -26,11 +26,23 @@
#include <linux/string.h>

enum {
- PT_MAX_OUTPUT_ADDRESS_LG2 = 52,
- PT_MAX_VA_ADDRESS_LG2 = 64,
PT_ITEM_WORD_SIZE = sizeof(u64),
+ /*
+ * The IOMMUFD selftest uses the AMDv1 format with some alterations It
+ * uses a 2k page size to test cases where the CPU page size is not the
+ * same.
+ */
+#ifdef AMDV1_IOMMUFD_SELFTEST
+ PT_MAX_VA_ADDRESS_LG2 = 56,
+ PT_MAX_OUTPUT_ADDRESS_LG2 = 51,
+ PT_MAX_TOP_LEVEL = 4,
+ PT_GRANULE_LG2SZ = 11,
+#else
+ PT_MAX_VA_ADDRESS_LG2 = 64,
+ PT_MAX_OUTPUT_ADDRESS_LG2 = 52,
PT_MAX_TOP_LEVEL = 5,
PT_GRANULE_LG2SZ = 12,
+#endif
PT_TABLEMEM_LG2SZ = 12,

/* The DTE only has these bits for the top phyiscal address */
@@ -374,6 +386,7 @@ static inline int amdv1pt_iommu_fmt_init(struct pt_iommu_amdv1 *iommu_table,
}
#define pt_iommu_fmt_init amdv1pt_iommu_fmt_init

+#ifndef PT_FMT_VARIANT
static inline void
amdv1pt_iommu_fmt_hw_info(struct pt_iommu_amdv1 *table,
const struct pt_range *top_range,
@@ -384,6 +397,7 @@ amdv1pt_iommu_fmt_hw_info(struct pt_iommu_amdv1 *table,
info->mode = top_range->top_level + 1;
}
#define pt_iommu_fmt_hw_info amdv1pt_iommu_fmt_hw_info
+#endif

#if defined(GENERIC_PT_KUNIT)
static const struct pt_iommu_amdv1_cfg amdv1_kunit_fmt_cfgs[] = {
diff --git a/drivers/iommu/generic_pt/fmt/iommu_mock.c b/drivers/iommu/generic_pt/fmt/iommu_mock.c
new file mode 100644
index 00000000000000..74e597cba9d9cd
--- /dev/null
+++ b/drivers/iommu/generic_pt/fmt/iommu_mock.c
@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2024-2025, NVIDIA CORPORATION & AFFILIATES
+ */
+#define AMDV1_IOMMUFD_SELFTEST 1
+#define PT_FMT amdv1
+#define PT_FMT_VARIANT mock
+#define PT_SUPPORTED_FEATURES 0
+
+#include "iommu_template.h"
diff --git a/include/linux/generic_pt/iommu.h b/include/linux/generic_pt/iommu.h
index 03a906fbe12a83..848a5fb76272a9 100644
--- a/include/linux/generic_pt/iommu.h
+++ b/include/linux/generic_pt/iommu.h
@@ -237,6 +237,12 @@ struct pt_iommu_amdv1_hw_info {

IOMMU_FORMAT(amdv1, amdpt);

+/* amdv1_mock is used by the iommufd selftest */
+#define pt_iommu_amdv1_mock pt_iommu_amdv1
+#define pt_iommu_amdv1_mock_cfg pt_iommu_amdv1_cfg
+struct pt_iommu_amdv1_mock_hw_info;
+IOMMU_PROTOTYPES(amdv1_mock);
+
#undef IOMMU_PROTOTYPES
#undef IOMMU_FORMAT
#endif
--
2.43.0