[PATCH 03/13] drm/amdgpu/UAPI: add new CS chunk for GFX shadow buffers

[Christian König]

Am 13.04.23 um 14:26 schrieb Alex Deucher:
> On Thu, Apr 13, 2023 at 7:32 AM Christian König
> <ckoenig.leichtzumerken at gmail.com> wrote:
>> Ok, then we have a problem.
>>
>> Alex what do you think?
> If you program it to 0, FW skips the GDS backup I think so UMD's can
> decide whether they want to use it or not, depending on whether they
> use GDS.

Yeah, but when Mesa isn't using it we have a hard way justifying to 
upstream that because it isn't tested at all.

Christian.

>
> Alex
>
>
>> Christian.
>>
>> Am 13.04.23 um 11:21 schrieb Marek Olšák:
>>
>> That's not why it was removed. It was removed because userspace doesn't use GDS memory and gds_va is always going to be 0.
>>
>> Firmware shouldn't use it because using it would increase preemption latency.
>>
>> Marek
>>
>> On Sun, Apr 9, 2023, 11:21 Christian König <ckoenig.leichtzumerken at gmail.com> wrote:
>>> We removed the GDS information because they were unnecessary. The GDS size was already part of the device info before we added the shadow info.
>>>
>>> But as far as I know the firmware needs valid VAs for all three buffers or won't work correctly.
>>>
>>> Christian.
>>>
>>> Am 06.04.23 um 17:01 schrieb Marek Olšák:
>>>
>>> There is no GDS shadowing info in the device info uapi, so userspace can't create any GDS buffer and thus can't have any GDS va. It's a uapi issue, not what firmware wants to do.
>>>
>>> Marek
>>>
>>> On Thu, Apr 6, 2023 at 6:31 AM Christian König <ckoenig.leichtzumerken at gmail.com> wrote:
>>>> That's what I thought as well, but Mitch/Hans insisted on that.
>>>>
>>>> We should probably double check internally.
>>>>
>>>> Christian.
>>>>
>>>> Am 06.04.23 um 11:43 schrieb Marek Olšák:
>>>>
>>>> GDS memory isn't used on gfx11. Only GDS OA is used.
>>>>
>>>> Marek
>>>>
>>>> On Thu, Apr 6, 2023 at 5:09 AM Christian König <christian.koenig at amd.com> wrote:
>>>>> Why that?
>>>>>
>>>>> This is the save buffer for GDS, not the old style GDS BOs.
>>>>>
>>>>> Christian.
>>>>>
>>>>> Am 06.04.23 um 09:36 schrieb Marek Olšák:
>>>>>
>>>>> gds_va is unnecessary.
>>>>>
>>>>> Marek
>>>>>
>>>>> On Thu, Mar 30, 2023 at 3:18 PM Alex Deucher <alexander.deucher at amd.com> wrote:
>>>>>> For GFX11, the UMD needs to allocate some shadow buffers
>>>>>> to be used for preemption.  The UMD allocates the buffers
>>>>>> and passes the GPU virtual address to the kernel since the
>>>>>> kernel will program the packet that specified these
>>>>>> addresses as part of its IB submission frame.
>>>>>>
>>>>>> v2: UMD passes shadow init to tell kernel when to initialize
>>>>>>      the shadow
>>>>>>
>>>>>> Reviewed-by: Christian König <christian.koenig at amd.com>
>>>>>> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
>>>>>> ---
>>>>>>   include/uapi/drm/amdgpu_drm.h | 10 ++++++++++
>>>>>>   1 file changed, 10 insertions(+)
>>>>>>
>>>>>> diff --git a/include/uapi/drm/amdgpu_drm.h b/include/uapi/drm/amdgpu_drm.h
>>>>>> index b6eb90df5d05..3d9474af6566 100644
>>>>>> --- a/include/uapi/drm/amdgpu_drm.h
>>>>>> +++ b/include/uapi/drm/amdgpu_drm.h
>>>>>> @@ -592,6 +592,7 @@ struct drm_amdgpu_gem_va {
>>>>>>   #define AMDGPU_CHUNK_ID_SCHEDULED_DEPENDENCIES 0x07
>>>>>>   #define AMDGPU_CHUNK_ID_SYNCOBJ_TIMELINE_WAIT    0x08
>>>>>>   #define AMDGPU_CHUNK_ID_SYNCOBJ_TIMELINE_SIGNAL  0x09
>>>>>> +#define AMDGPU_CHUNK_ID_CP_GFX_SHADOW   0x0a
>>>>>>
>>>>>>   struct drm_amdgpu_cs_chunk {
>>>>>>          __u32           chunk_id;
>>>>>> @@ -708,6 +709,15 @@ struct drm_amdgpu_cs_chunk_data {
>>>>>>          };
>>>>>>   };
>>>>>>
>>>>>> +#define AMDGPU_CS_CHUNK_CP_GFX_SHADOW_FLAGS_INIT_SHADOW         0x1
>>>>>> +
>>>>>> +struct drm_amdgpu_cs_chunk_cp_gfx_shadow {
>>>>>> +       __u64 shadow_va;
>>>>>> +       __u64 csa_va;
>>>>>> +       __u64 gds_va;
>>>>>> +       __u64 flags;
>>>>>> +};
>>>>>> +
>>>>>>   /*
>>>>>>    *  Query h/w info: Flag that this is integrated (a.h.a. fusion) GPU
>>>>>>    *
>>>>>> --
>>>>>> 2.39.2
>>>>>>