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

[Joshi, Mukul]

[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

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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?

Thanks,
Mukul

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

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