[PATCH v6 7/9] drm/amdgpu: map wptr BO into GART

[Shashank Sharma]

Hey Felix,

On 04/10/2023 23:34, Felix Kuehling wrote:
>
> On 2023-09-18 06:32, Christian König wrote:
>> Am 08.09.23 um 18:04 schrieb Shashank Sharma:
>>> To support oversubscription, MES FW expects WPTR BOs to
>>> be mapped into GART, before they are submitted to usermode
>>> queues. This patch adds a function for the same.
>>>
>>> V4: fix the wptr value before mapping lookup (Bas, Christian).
>>> V5: Addressed review comments from Christian:
>>>      - Either pin object or allocate from GART, but not both.
>>>      - All the handling must be done with the VM locks held.
>>>
>>> Cc: Alex Deucher <alexander.deucher at amd.com>
>>> Cc: Christian Koenig <christian.koenig at amd.com>
>>> Signed-off-by: Shashank Sharma <shashank.sharma at amd.com>
>>> Signed-off-by: Arvind Yadav <arvind.yadav at amd.com>
>>> ---
>>>   drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c        | 81 
>>> +++++++++++++++++++
>>>   .../gpu/drm/amd/include/amdgpu_userqueue.h    |  1 +
>>>   2 files changed, 82 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c 
>>> b/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c
>>> index e266674e0d44..c0eb622dfc37 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c
>>> @@ -6427,6 +6427,79 @@ const struct amdgpu_ip_block_version 
>>> gfx_v11_0_ip_block =
>>>       .funcs = &gfx_v11_0_ip_funcs,
>>>   };
>>>   +static int
>>> +gfx_v11_0_map_gtt_bo_to_gart(struct amdgpu_device *adev, struct 
>>> amdgpu_bo *bo)
>>> +{
>>> +    int ret;
>>> +
>>> +    ret = amdgpu_bo_reserve(bo, true);
>>> +    if (ret) {
>>> +        DRM_ERROR("Failed to reserve bo. ret %d\n", ret);
>>> +        goto err_reserve_bo_failed;
>>> +    }
>>> +
>>> +    ret = amdgpu_ttm_alloc_gart(&bo->tbo);
>>> +    if (ret) {
>>> +        DRM_ERROR("Failed to bind bo to GART. ret %d\n", ret);
>>> +        goto err_map_bo_gart_failed;
>>> +    }
>>> +
>>> +    amdgpu_bo_unreserve(bo);
>>
>> The GART mapping can become invalid as soon as you unlock the BOs.
>>
>> You need to attach an eviction fence for this to work correctly.
>
> Don't you need an eviction fence on the WPTR BO regardless of the GTT 
> mapping?

Yes, Christian also mentioned this in this iteration, I have implemented 
the basic eviction fence for [V7], I will publish it soon.

- Shashank

>
> Regards,
>   Felix
>
>
>>
>>> +    bo = amdgpu_bo_ref(bo);
>>> +
>>> +    return 0;
>>> +
>>> +err_map_bo_gart_failed:
>>> +    amdgpu_bo_unreserve(bo);
>>> +err_reserve_bo_failed:
>>> +    return ret;
>>> +}
>>> +
>>> +static int
>>> +gfx_v11_0_create_wptr_mapping(struct amdgpu_device *adev,
>>> +                  struct amdgpu_usermode_queue *queue,
>>> +                  uint64_t wptr)
>>> +{
>>> +    struct amdgpu_bo_va_mapping *wptr_mapping;
>>> +    struct amdgpu_vm *wptr_vm;
>>> +    struct amdgpu_bo *wptr_bo = NULL;
>>> +    int ret;
>>> +
>>> +    mutex_lock(&queue->vm->eviction_lock);
>>
>> Never ever touch the eviction lock outside of the VM code! That lock 
>> is completely unrelated to what you do here.
>>
>>> +    wptr_vm = queue->vm;
>>> +    ret = amdgpu_bo_reserve(wptr_vm->root.bo, false);
>>> +    if (ret)
>>> +        goto unlock;
>>> +
>>> +    wptr &= AMDGPU_GMC_HOLE_MASK;
>>> +    wptr_mapping = amdgpu_vm_bo_lookup_mapping(wptr_vm, wptr >> 
>>> PAGE_SHIFT);
>>> +    amdgpu_bo_unreserve(wptr_vm->root.bo);
>>> +    if (!wptr_mapping) {
>>> +        DRM_ERROR("Failed to lookup wptr bo\n");
>>> +        ret = -EINVAL;
>>> +        goto unlock;
>>> +    }
>>> +
>>> +    wptr_bo = wptr_mapping->bo_va->base.bo;
>>> +    if (wptr_bo->tbo.base.size > PAGE_SIZE) {
>>> +        DRM_ERROR("Requested GART mapping for wptr bo larger than 
>>> one page\n");
>>> +        ret = -EINVAL;
>>> +        goto unlock;
>>> +    }
>>
>> We probably also want to enforce that this BO is a per VM BO.
>>
>>> +
>>> +    ret = gfx_v11_0_map_gtt_bo_to_gart(adev, wptr_bo);
>>> +    if (ret) {
>>> +        DRM_ERROR("Failed to map wptr bo to GART\n");
>>> +        goto unlock;
>>> +    }
>>> +
>>> +    queue->wptr_mc_addr = wptr_bo->tbo.resource->start << PAGE_SHIFT;
>>
>> This needs to be amdgpu_bo_gpu_offset() instead.
>>
>> Regards,
>> Christian.
>>
>>> +
>>> +unlock:
>>> +    mutex_unlock(&queue->vm->eviction_lock);
>>> +    return ret;
>>> +}
>>> +
>>>   static void gfx_v11_0_userq_unmap(struct amdgpu_userq_mgr *uq_mgr,
>>>                     struct amdgpu_usermode_queue *queue)
>>>   {
>>> @@ -6475,6 +6548,7 @@ static int gfx_v11_0_userq_map(struct 
>>> amdgpu_userq_mgr *uq_mgr,
>>>       queue_input.queue_size = userq_props->queue_size >> 2;
>>>       queue_input.doorbell_offset = userq_props->doorbell_index;
>>>       queue_input.page_table_base_addr = 
>>> amdgpu_gmc_pd_addr(queue->vm->root.bo);
>>> +    queue_input.wptr_mc_addr = queue->wptr_mc_addr;
>>>         amdgpu_mes_lock(&adev->mes);
>>>       r = adev->mes.funcs->add_hw_queue(&adev->mes, &queue_input);
>>> @@ -6601,6 +6675,13 @@ static int gfx_v11_0_userq_mqd_create(struct 
>>> amdgpu_userq_mgr *uq_mgr,
>>>           goto free_mqd;
>>>       }
>>>   +    /* FW expects WPTR BOs to be mapped into GART */
>>> +    r = gfx_v11_0_create_wptr_mapping(adev, queue, 
>>> userq_props.wptr_gpu_addr);
>>> +    if (r) {
>>> +        DRM_ERROR("Failed to create WPTR mapping\n");
>>> +        goto free_ctx;
>>> +    }
>>> +
>>>       /* Map userqueue into FW using MES */
>>>       r = gfx_v11_0_userq_map(uq_mgr, queue, &userq_props);
>>>       if (r) {
>>> diff --git a/drivers/gpu/drm/amd/include/amdgpu_userqueue.h 
>>> b/drivers/gpu/drm/amd/include/amdgpu_userqueue.h
>>> index 34e20daa06c8..ae155de62560 100644
>>> --- a/drivers/gpu/drm/amd/include/amdgpu_userqueue.h
>>> +++ b/drivers/gpu/drm/amd/include/amdgpu_userqueue.h
>>> @@ -39,6 +39,7 @@ struct amdgpu_usermode_queue {
>>>       int            queue_type;
>>>       uint64_t        doorbell_handle;
>>>       uint64_t        doorbell_index;
>>> +    uint64_t        wptr_mc_addr;
>>>       uint64_t        flags;
>>>       struct amdgpu_mqd_prop    *userq_prop;
>>>       struct amdgpu_userq_mgr *userq_mgr;
>>