[PATCH 3/8] drm/amdgpu: Implement mmap as GEM object function

[Thomas Zimmermann]

Hi

Am 07.04.21 um 21:49 schrieb Felix Kuehling:
> On 2021-04-07 3:34 p.m., Felix Kuehling wrote:
>> On 2021-04-07 7:25 a.m., Christian König wrote:
>>>>>>> +    /*
>>>>>>> +     * Don't verify access for KFD BOs. They don't have a GEM
>>>>>>> +     * object associated with them.
>>>>>>> +     */
>>>>>>> +    if (bo->kfd_bo)
>>>>>>> +        goto out;
>>>>>> Who does the access verification now?
>>>>> This is somewhat confusing.
>>>>>
>>>>> I took this check as-is, including the comment, from amdgpu's
>>>>> verify_access function. The verify_access function was called by
>>>>> ttm_bo_mmap. It returned 0 and ttm_bo_mmap did the mapping.
>>>> This is probably a left-over from when we mapped BOs using /dev/kfd. We
>>>> changed this to use /dev/dri/renderD* a long time ago to fix CPU 
>>>> mapping
>>>> invalidations on memory evictions. I think we can let GEM do the access
>>>> check.
>>>
>>> Ok, good to know.
>>>
>>> Thomas can you remove the extra handling in a separate prerequisite 
>>> patch?
>>>
>>> If anybody then bisects to this patch we at least know what to do to 
>>> get it working again.
>>
>> FWIW, I ran KFDTest test with this shortcut removed on current 
>> amd-staging-drm-next + my HMM patch series, and it didn't seem to 
>> cause any issues.
> 
> Wait, I celebrated too soon. I was running the wrong kernel. I do see 
> some failures where access is being denied. I need to do more debugging 
> to figure out what's causing that.

OK, thanks for looking into this. I'll wait a bit before sending out the 
new patchset.

Best regards
Thomas

> 
> Regards,
>    Felix
> 
> 
>>
>> Regards,
>>   Felix
>>
>>
>>>
>>> Regards,
>>> Christian. 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

-------------- next part --------------
A non-text attachment was scrubbed...
Name: OpenPGP_signature
Type: application/pgp-signature
Size: 840 bytes
Desc: OpenPGP digital signature
URL: <https://lists.freedesktop.org/archives/amd-gfx/attachments/20210408/d4fe652e/attachment.sig>