[PATCH] Find bo_va before create it when map bo into compute VM

["Xiaogang.Chen" <xiaogang.chen@xxxxxxx>]

From: Xiaogang Chen <xiaogang.chen@xxxxxxx>

This is needed to correctly handle BOs imported into compute VM from gfx.
Both kfd and gfx should use same bo_va when map the Bos into same VM, otherwise
we may trigger kernel general protection when iterate mappings from bo_va.

Signed-off-by: Felix Kuehling <Felix.Kuehling@xxxxxxx>
Acked-by: Christian König <christian.koenig@xxxxxxx>
Reviewed-by: Ramesh Errabolu <Ramesh.Errabolu@xxxxxxx>
Reviewed-By: Xiaogang Chen <Xiaogang.Chen@xxxxxxx>
Tested-By: Xiaogang Chen <Xiaogang.Chen@xxxxxxx>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
index a15e59abe70a..c1ec93cc50ae 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
@@ -832,6 +832,7 @@ static int kfd_mem_attach(struct amdgpu_device *adev, struct kgd_mem *mem,
 	uint64_t va = mem->va;
 	struct kfd_mem_attachment *attachment[2] = {NULL, NULL};
 	struct amdgpu_bo *bo[2] = {NULL, NULL};
+	struct amdgpu_bo_va *bo_va;
 	bool same_hive = false;
 	int i, ret;
 
@@ -919,7 +920,13 @@ static int kfd_mem_attach(struct amdgpu_device *adev, struct kgd_mem *mem,
 			pr_debug("Unable to reserve BO during memory attach");
 			goto unwind;
 		}
-		attachment[i]->bo_va = amdgpu_vm_bo_add(adev, vm, bo[i]);
+		bo_va = amdgpu_vm_bo_find(vm, bo[i]);
+		if (!bo_va)
+			bo_va = amdgpu_vm_bo_add(adev, vm, bo[i]);
+		else
+			++bo_va->ref_count;
+		attachment[i]->bo_va = bo_va;
+
 		amdgpu_bo_unreserve(bo[i]);
 		if (unlikely(!attachment[i]->bo_va)) {
 			ret = -ENOMEM;
@@ -943,7 +950,8 @@ static int kfd_mem_attach(struct amdgpu_device *adev, struct kgd_mem *mem,
 			continue;
 		if (attachment[i]->bo_va) {
 			amdgpu_bo_reserve(bo[i], true);
-			amdgpu_vm_bo_del(adev, attachment[i]->bo_va);
+			if (--attachment[i]->bo_va->ref_count == 0)
+				amdgpu_vm_bo_del(adev, attachment[i]->bo_va);
 			amdgpu_bo_unreserve(bo[i]);
 			list_del(&attachment[i]->list);
 		}
-- 
2.25.1