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drm/amdgpu: Restore uncached behaviour on GFX12
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Always use MTYPE_UC if UNCACHED flag is specified.

This makes kernarg region uncached and it restores
usermode cache disable debug flag functionality.

Do not set MTYPE_UC for COHERENT flag, on GFX12 coherence is handled by
shader code.

Signed-off-by: David Belanger <david.belanger@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit eb6cdfb)
Cc: stable@vger.kernel.org # 6.12.x
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David Belanger authored and Alex Deucher committed Mar 18, 2025
1 parent 86730b5 commit 35b6162
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Showing 2 changed files with 3 additions and 27 deletions.
22 changes: 2 additions & 20 deletions drivers/gpu/drm/amd/amdgpu/gmc_v12_0.c
Original file line number Diff line number Diff line change
Expand Up @@ -501,9 +501,6 @@ static void gmc_v12_0_get_vm_pte(struct amdgpu_device *adev,
uint64_t *flags)
{
struct amdgpu_bo *bo = mapping->bo_va->base.bo;
struct amdgpu_device *bo_adev;
bool coherent, is_system;


*flags &= ~AMDGPU_PTE_EXECUTABLE;
*flags |= mapping->flags & AMDGPU_PTE_EXECUTABLE;
Expand All @@ -519,26 +516,11 @@ static void gmc_v12_0_get_vm_pte(struct amdgpu_device *adev,
*flags &= ~AMDGPU_PTE_VALID;
}

if (!bo)
return;

if (bo->flags & (AMDGPU_GEM_CREATE_COHERENT |
AMDGPU_GEM_CREATE_UNCACHED))
*flags = AMDGPU_PTE_MTYPE_GFX12(*flags, MTYPE_UC);

bo_adev = amdgpu_ttm_adev(bo->tbo.bdev);
coherent = bo->flags & AMDGPU_GEM_CREATE_COHERENT;
is_system = bo->tbo.resource &&
(bo->tbo.resource->mem_type == TTM_PL_TT ||
bo->tbo.resource->mem_type == AMDGPU_PL_PREEMPT);

if (bo && bo->flags & AMDGPU_GEM_CREATE_GFX12_DCC)
*flags |= AMDGPU_PTE_DCC;

/* WA for HW bug */
if (is_system || ((bo_adev != adev) && coherent))
*flags = AMDGPU_PTE_MTYPE_GFX12(*flags, MTYPE_NC);

if (bo && bo->flags & AMDGPU_GEM_CREATE_UNCACHED)
*flags = AMDGPU_PTE_MTYPE_GFX12(*flags, MTYPE_UC);
}

static unsigned gmc_v12_0_get_vbios_fb_size(struct amdgpu_device *adev)
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8 changes: 1 addition & 7 deletions drivers/gpu/drm/amd/amdkfd/kfd_svm.c
Original file line number Diff line number Diff line change
Expand Up @@ -1286,13 +1286,7 @@ svm_range_get_pte_flags(struct kfd_node *node,
break;
case IP_VERSION(12, 0, 0):
case IP_VERSION(12, 0, 1):
if (domain == SVM_RANGE_VRAM_DOMAIN) {
if (bo_node != node)
mapping_flags |= AMDGPU_VM_MTYPE_NC;
} else {
mapping_flags |= coherent ?
AMDGPU_VM_MTYPE_UC : AMDGPU_VM_MTYPE_NC;
}
mapping_flags |= AMDGPU_VM_MTYPE_NC;
break;
default:
mapping_flags |= coherent ?
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