[PATCH 2/2] drm/amdgpu: Reduce SG bo memory usage for mGPUs

[Philip Yang]

For userptr bo, if adev is not in IOMMU isolation mode, multiple GPUs
use same system memory page dma mapping address, they can share the
original mem->bo in attachment to reduce dma address array memory usage.

Signed-off-by: Philip Yang <Philip.Yang at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
index b8490789eef4..03807ed1f6e2 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
@@ -708,10 +708,14 @@ static int kfd_mem_attach(struct amdgpu_device *adev, struct kgd_mem *mem,
 		pr_debug("\t add VA 0x%llx - 0x%llx to vm %p\n", va,
 			 va + bo_size, vm);
 
-		if (adev == bo_adev || (mem->domain == AMDGPU_GEM_DOMAIN_VRAM &&
-					amdgpu_xgmi_same_hive(adev, bo_adev))) {
-			/* Mappings on the local GPU and VRAM mappings in the
-			 * local hive share the original BO
+		if (adev == bo_adev ||
+		    (amdgpu_ttm_tt_get_usermm(mem->bo->tbo.ttm) &&
+		     !adev->iommu_isolation) ||
+		    (mem->domain == AMDGPU_GEM_DOMAIN_VRAM &&
+		     amdgpu_xgmi_same_hive(adev, bo_adev))) {
+			/* Mappings on the local GPU, or VRAM mappings in the
+			 * local hive, or userptr mapping IOMMU is not isolation
+			 * mode share the original BO
 			 */
 			attachment[i]->type = KFD_MEM_ATT_SHARED;
 			bo[i] = mem->bo;
-- 
2.17.1