drm/amdgpu: reject mapping a reserved doorbell to a new queue

When creating an user-queue, the user space
provides a doorbell BO handle and an offset within
the bo to obtain a doorbell.

However current implementation using xa_store_irq()
to store a doorbell, which allows a later queue created
with the same BO and offset parameters to overwrite an
existing queue and doorbell mapping.

This can cause problems like misrouting fence IRQ
processing to a wrong queue, and mislead the cleanup
process of one queue erasing the mapping of another queue.

This commit fixes this issue by replacing xa_store_irq with
xa_insert_irq, which rejects mapping a reserved
doorbell to a newly created queue

Signed-off-by: Zhu Lingshan <lingshan.zhu@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
index fb4cc6bfb5ac..82c8809d1d9c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
@@ -702,8 +702,8 @@ amdgpu_userq_create(struct drm_file *filp, union drm_amdgpu_userq *args)
 	/* Update VM owner at userq submit-time for page-fault attribution. */
 	amdgpu_vm_set_task_info(&fpriv->vm);
 
-	r = xa_err(xa_store_irq(&adev->userq_doorbell_xa, index, queue,
-				GFP_KERNEL));
+	r = xa_insert_irq(&adev->userq_doorbell_xa, index, queue,
+			  GFP_KERNEL);
 	if (r)
 		goto clean_mqd;