[PATCH v1] drm/amdgpu: fix root reservation in amdgpu_vm_handle_fault

[Pierre-Eric Pelloux-Prayer]

svm_range_restore_pages might reserve the root bo so it must
be called after unreserving it.

The code checking that the VM still exists can be moved in the
"if" block, since the VM can only be removed when the root bo
is not reserved.

Fixes: 32b486e8541c ("drm/amdgpu: extract amdgpu_vm_lock_by_pasid from amdgpu_vm_handle_fault")
Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@xxxxxxx>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 35 +++++++++++---------------
 1 file changed, 15 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index 63156289ae7f..d86be0108913 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -2975,25 +2975,12 @@ struct amdgpu_vm *amdgpu_vm_lock_by_pasid(struct amdgpu_device *adev,
 		return NULL;
 
 	r = amdgpu_bo_reserve(*root, true);
-	if (r)
-		goto error_unref;
-
-	/* Double check that the VM still exists */
-	xa_lock_irqsave(&adev->vm_manager.pasids, irqflags);
-	vm = xa_load(&adev->vm_manager.pasids, pasid);
-	if (vm && vm->root.bo != *root)
-		vm = NULL;
-	xa_unlock_irqrestore(&adev->vm_manager.pasids, irqflags);
-	if (!vm)
-		goto error_unlock;
+	if (r) {
+		amdgpu_bo_unref(root);
+		return NULL;
+	}
 
 	return vm;
-error_unlock:
-	amdgpu_bo_unreserve(*root);
-
-error_unref:
-	amdgpu_bo_unref(root);
-	return NULL;
 }
 
 /**
@@ -3026,11 +3013,19 @@ bool amdgpu_vm_handle_fault(struct amdgpu_device *adev, u32 pasid,
 
 	is_compute_context = vm->is_compute_context;
 
-	if (is_compute_context && !svm_range_restore_pages(adev, pasid, vmid,
-	    node_id, addr >> PAGE_SHIFT, ts, write_fault)) {
+	if (is_compute_context) {
+		/* Unreserve root since svm_range_restore_pages might try to reserve it. */
 		amdgpu_bo_unreserve(root);
 		amdgpu_bo_unref(&root);
-		return true;
+
+		if (!svm_range_restore_pages(adev, pasid, vmid,
+					     node_id, addr >> PAGE_SHIFT, ts, write_fault))
+			return true;
+
+		/* Double check that the VM still exists. */
+		vm = amdgpu_vm_lock_by_pasid(adev, &root, pasid);
+		if (!vm)
+			return false;
 	}
 
 	addr /= AMDGPU_GPU_PAGE_SIZE;
-- 
2.43.0