[PATCH v7 10/15] iommupt: Add a mock pagetable format for iommufd selftest to use

[Samiullah Khawaja]

On Thu, Oct 23, 2025 at 11:21 AM Jason Gunthorpe <jgg at nvidia.com> wrote:
>
> 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.
>
> Tested-by: Alejandro Jimenez <alejandro.j.jimenez at oracle.com>
> Reviewed-by: Kevin Tian <kevin.tian at intel.com>
> Signed-off-by: Jason Gunthorpe <jgg at 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 706a70c8603017..81ced24585ff93 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 */
> @@ -378,6 +390,7 @@ 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,
> @@ -388,6 +401,7 @@ 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
>
>

Reviewed-by: Samiullah Khawaja <skhawaja at google.com>