[PATCH 2/3] drm/amdgpu: always sending PSP messages LOAD_ASD and UNLOAD_TA

[vitaly.prosyak]

From: Vitaly Prosyak <vitaly.pros...@amd.com>

We allow sending PSP messages LOAD_ASD and UNLOAD_TA without
acquiring a lock in drm_dev_enter during driver unload
because we must call drm_dev_unplug as the beginning
of unload driver sequence.
Added WARNING if other PSP messages are sent without a lock.
After this commit, the following commands would work
 -sudo modprobe -r amdgpu
 -sudo modprobe amdgpu

Signed-off-by: Vitaly Prosyak <vitaly.pros...@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c
index a8391f269cd0..40929f34447c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c
@@ -606,12 +606,21 @@ psp_cmd_submit_buf(struct psp_context *psp,
        int timeout = 20000;
        bool ras_intr = false;
        bool skip_unsupport = false;
+       bool dev_entered;
 
        if (psp->adev->no_hw_access)
                return 0;
 
-       if (!drm_dev_enter(adev_to_drm(psp->adev), &idx))
-               return 0;
+       dev_entered = drm_dev_enter(adev_to_drm(psp->adev), &idx);
+       /*
+        * We allow sending PSP messages LOAD_ASD and UNLOAD_TA without 
acquiring
+        * a lock in drm_dev_enter during driver unload because we must call
+        * drm_dev_unplug as the beginning  of unload driver sequence . It is 
very
+        * crucial that userspace can't access device instances anymore.
+        */
+       if (!dev_entered)
+               WARN_ON(psp->cmd_buf_mem->cmd_id != GFX_CMD_ID_LOAD_ASD &&
+                       psp->cmd_buf_mem->cmd_id != GFX_CMD_ID_UNLOAD_TA);
 
        memset(psp->cmd_buf_mem, 0, PSP_CMD_BUFFER_SIZE);
 
@@ -676,7 +685,8 @@ psp_cmd_submit_buf(struct psp_context *psp,
        }
 
 exit:
-       drm_dev_exit(idx);
+       if (dev_entered)
+               drm_dev_exit(idx);
        return ret;
 }
 
-- 
2.25.1