[PATCH v2 10/15] iommupt: Add a mock pagetable format for iommufd selftest to use

[Jason Gunthorpe <jgg@nvidia.com>]

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.

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 c108ca97aa4ec5..33b4bedac61782 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_ENTRY_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,
 };
 
@@ -370,6 +382,7 @@ 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,
@@ -380,6 +393,7 @@ 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 aac565611cbffa..38a19b19cdc3dc 100644
--- a/include/linux/generic_pt/iommu.h
+++ b/include/linux/generic_pt/iommu.h
@@ -230,6 +230,12 @@ 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