[PATCH v2] drm/amdgpu: fix the wrong logic checking when secure buffer is created (v2)

[Christian König]

Am 18.02.20 um 09:55 schrieb Huang Rui:
> On Tue, Feb 18, 2020 at 04:50:01PM +0800, Koenig, Christian wrote:
>> Am 18.02.20 um 09:30 schrieb Huang Rui:
>>> While the current amdgpu doesn't support TMZ, it will return the error if user
>>> mode would like to allocate secure buffer.
>>>
>>> Fixes: 17d907c drm/amdgpu: implement TMZ accessor (v3)
>>>
>>> v2: we didn't need this checking anymore.
>> You misunderstood me.
>>
> ok...
>
>>> Signed-off-by: Huang Rui <ray.huang at amd.com>
>>> ---
>>>    drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 5 -----
>>>    1 file changed, 5 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
>>> index b51a060..5cbc63a 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
>>> @@ -235,11 +235,6 @@ int amdgpu_gem_create_ioctl(struct drm_device *dev, void *data,
>>>    	if (args->in.domains & ~AMDGPU_GEM_DOMAIN_MASK)
>>>    		return -EINVAL;
>>>    
>>> -	if (amdgpu_is_tmz(adev) && (flags & AMDGPU_GEM_CREATE_ENCRYPTED)) {
>>> -		DRM_ERROR("Cannot allocate secure buffer since TMZ is disabled\n");
>> Only the error message should be removed, but we still need to test the
>> flag.
>>
>> E.g. in general we should never log that userspace sends invalid parameters.
>>
> Why? It probably can help userspace to understand what wrong input it is.

That's correct, but it also allows userspace to spam the logs with those 
messages.

While the kernel tools are rather clever and filter out repeated 
messages this is still considered a bad idea because it might hide more 
serious error messages.

What we could do is either make this debug severity or use something 
DRM_NOTE_ONCE() to print it only once.

Regards,
Christian.

>
> Thanks,
> Ray