drm/amdgpu: Improve Vega20 XGMI TLB flush workaround

Using a heavy-weight TLB flush once is not sufficient. Concurrent
memory accesses in the same TLB cache line can re-populate TLB entries
from stale texture cache (TC) entries while the heavy-weight TLB
flush is in progress. To fix this race condition, perform another TLB
flush after the heavy-weight one, when TC is known to be clean.

Move the workaround into the low-level TLB flushing functions. This way
they apply to amdgpu as well, and KIQ-based TLB flush only needs to
synchronize once.

Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: shaoyun liu <shaoyun.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 1 insertions, 5 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
index 314c4a2a0354..e1c2c182898f 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
@@ -647,13 +647,9 @@ int amdgpu_amdkfd_flush_gpu_tlb_vmid(struct kgd_dev *kgd, uint16_t vmid)
 int amdgpu_amdkfd_flush_gpu_tlb_pasid(struct kgd_dev *kgd, uint16_t pasid)
 {
 	struct amdgpu_device *adev = (struct amdgpu_device *)kgd;
-	uint32_t flush_type = 0;
+	const uint32_t flush_type = 0;
 	bool all_hub = false;
 
-	if (adev->gmc.xgmi.num_physical_nodes &&
-		adev->asic_type == CHIP_VEGA20)
-		flush_type = 2;
-
 	if (adev->family == AMDGPU_FAMILY_AI)
 		all_hub = true;