[PATCH] drm/amdgpu/gmc9: fix 64 bit division in partition code

[Alex Deucher]

On Wed, May 17, 2023 at 12:26 PM Joshi, Mukul <Mukul.Joshi at amd.com> wrote:
>
> [AMD Official Use Only - General]
>
>
> Hi Alex,
>
> ________________________________
> From: amd-gfx <amd-gfx-bounces at lists.freedesktop.org> on behalf of Alex Deucher <alexander.deucher at amd.com>
> Sent: Wednesday, May 17, 2023 10:31 AM
> To: amd-gfx at lists.freedesktop.org <amd-gfx at lists.freedesktop.org>
> Cc: Deucher, Alexander <Alexander.Deucher at amd.com>; Chen, Guchun <Guchun.Chen at amd.com>
> Subject: [PATCH] drm/amdgpu/gmc9: fix 64 bit division in partition code
>
> Caution: This message originated from an External Source. Use proper caution when opening attachments, clicking links, or responding.
>
>
> Rework logic or use do_div() to avoid problems on 32 bit.
>
> v2: add a missing case for XCP macro
>
> Acked-by: Guchun Chen <guchun.chen at amd.com> (v1)
> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c | 14 ++++++++++++++
>  drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h |  9 ++++-----
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c    |  5 ++++-
>  drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c      | 11 ++++++-----
>  4 files changed, 28 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
> index 739eb7c0d133..fed545cdd1de 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
> @@ -794,3 +794,17 @@ void amdgpu_amdkfd_unlock_kfd(struct amdgpu_device *adev)
>  {
>         kgd2kfd_unlock_kfd();
>  }
> +
> +
> +u64 amdgpu_amdkfd_xcp_memory_size(struct amdgpu_device *adev, int xcp_id)
> +{
> +       u64 tmp;
> +
> +       if (adev->gmc.num_mem_partitions && xcp_id >= 0) {
> +               tmp = adev->gmc.mem_partitions[KFD_XCP_MEM_ID(adev, xcp_id)].size;
> +               do_div(tmp, adev->xcp_mgr->num_xcp_per_mem_partition);
> +               return tmp;
> +       } else {
> +               return adev->gmc.real_vram_size;
> +       }
> +}
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
> index be43d71ba7ef..94cc456761e5 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
> @@ -333,15 +333,14 @@ int amdgpu_amdkfd_reserve_mem_limit(struct amdgpu_device *adev,
>  void amdgpu_amdkfd_unreserve_mem_limit(struct amdgpu_device *adev,
>                 uint64_t size, u32 alloc_flag, int8_t xcp_id);
>
> +u64 amdgpu_amdkfd_xcp_memory_size(struct amdgpu_device *adev, int xcp_id);
> +
>  #define KFD_XCP_MEM_ID(adev, xcp_id) \
>                 ((adev)->xcp_mgr && (xcp_id) >= 0 ?\
>                 (adev)->xcp_mgr->xcp[(xcp_id)].mem_id : -1)
>
> -#define KFD_XCP_MEMORY_SIZE(adev, xcp_id)\
> -               ((adev)->gmc.num_mem_partitions && (xcp_id) >= 0 ?\
> -               (adev)->gmc.mem_partitions[KFD_XCP_MEM_ID((adev), (xcp_id))].size /\
> -               (adev)->xcp_mgr->num_xcp_per_mem_partition :\
> -               (adev)->gmc.real_vram_size)
> +#define KFD_XCP_MEMORY_SIZE(adev, xcp_id) amdgpu_amdkfd_xcp_memory_size((adev), (xcp_id))
> +
>
>  #if IS_ENABLED(CONFIG_HSA_AMD)
>  void amdgpu_amdkfd_gpuvm_init_mem_limits(void);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index ad664ef640ff..34724b771ace 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -818,11 +818,14 @@ static void amdgpu_ttm_gart_bind_gfx9_mqd(struct amdgpu_device *adev,
>         struct amdgpu_ttm_tt *gtt = (void *)ttm;
>         uint64_t total_pages = ttm->num_pages;
>         int num_xcc = max(1U, adev->gfx.num_xcc_per_xcp);
> -       uint64_t page_idx, pages_per_xcc = total_pages / num_xcc;
> +       uint64_t page_idx, pages_per_xcc;
>         int i;
>         uint64_t ctrl_flags = (flags & ~AMDGPU_PTE_MTYPE_VG10_MASK) |
>                         AMDGPU_PTE_MTYPE_VG10(AMDGPU_MTYPE_NC);
>
> +       pages_per_xcc = total_pages;
> +       do_div(pages_per_xcc, num_xcc);
> +
>         for (i = 0, page_idx = 0; i < num_xcc; i++, page_idx += pages_per_xcc) {
>                 /* MQD page: use default flags */
>                 amdgpu_gart_bind(adev,
> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> index 938c8dba9057..d559e7bc0f09 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> @@ -1919,9 +1919,10 @@ gmc_v9_0_init_acpi_mem_ranges(struct amdgpu_device *adev,
>         adev->gmc.num_mem_partitions = num_ranges;
>
>         /* If there is only partition, don't use entire size */
> -       if (adev->gmc.num_mem_partitions == 1)
> -               mem_ranges[0].size =
> -                       (mem_ranges[0].size * (mem_groups - 1) / mem_groups);
> +       if (adev->gmc.num_mem_partitions == 1) {
> +               mem_ranges[0].size = mem_ranges[0].size * (mem_groups - 1);
> +               do_div(mem_ranges[0].size, mem_groups);
> +       }
>  }
>
>  static void
> @@ -1953,8 +1954,8 @@ gmc_v9_0_init_sw_mem_ranges(struct amdgpu_device *adev,
>                 break;
>         }
>
> -       size = (adev->gmc.real_vram_size >> AMDGPU_GPU_PAGE_SHIFT) /
> -              adev->gmc.num_mem_partitions;
> +       size = adev->gmc.real_vram_size >> AMDGPU_GPU_PAGE_SHIFT;
> +       size /= adev->gmc.num_mem_partitions;
>
> Did you miss using the do_div() here?

It's not needed here.  size is 32 bits IIRC.

Alex

>
> Thanks,
> Mukul
>
>         for (i = 0; i < adev->gmc.num_mem_partitions; ++i) {
>                 mem_ranges[i].range.fpfn = start_addr;
> --
> 2.40.1
>