[PATCH 1/5] drm/amdgpu: allow direct submission in the VM backends

[Christian König]

Am 28.06.19 um 16:30 schrieb Chunming Zhou:
> 在 2019/6/28 20:18, Christian König 写道:
>> This allows us to update page tables directly while in a page fault.
>>
>> Signed-off-by: Christian König <christian.koenig at amd.com>
>> ---
>>    drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h      |  5 ++++
>>    drivers/gpu/drm/amd/amdgpu/amdgpu_vm_cpu.c  |  4 +++
>>    drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c | 29 +++++++++++++--------
>>    3 files changed, 27 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>> index 489a162ca620..5941accea061 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>> @@ -197,6 +197,11 @@ struct amdgpu_vm_update_params {
>>    	 */
>>    	struct amdgpu_vm *vm;
>>    
>> +	/**
>> +	 * @direct: if changes should be made directly
>> +	 */
>> +	bool direct;
>> +
>>    	/**
>>    	 * @pages_addr:
>>    	 *
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_cpu.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_cpu.c
>> index 5222d165abfc..f94e4896079c 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_cpu.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_cpu.c
>> @@ -49,6 +49,10 @@ static int amdgpu_vm_cpu_prepare(struct amdgpu_vm_update_params *p, void *owner,
>>    {
>>    	int r;
>>    
>> +	/* Don't wait for anything during page fault */
>> +	if (p->direct)
>> +		return 0;
>> +
>>    	/* Wait for PT BOs to be idle. PTs share the same resv. object
>>    	 * as the root PD BO
>>    	 */
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c
>> index ddd181f5ed37..891d597063cb 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c
>> @@ -68,17 +68,17 @@ static int amdgpu_vm_sdma_prepare(struct amdgpu_vm_update_params *p,
>>    	if (r)
>>    		return r;
>>    
>> -	r = amdgpu_sync_fence(p->adev, &p->job->sync, exclusive, false);
>> -	if (r)
>> -		return r;
>> +	p->num_dw_left = ndw;
>> +
>> +	if (p->direct)
>> +		return 0;
>>    
>> -	r = amdgpu_sync_resv(p->adev, &p->job->sync, root->tbo.resv,
>> -			     owner, false);
>> +	r = amdgpu_sync_fence(p->adev, &p->job->sync, exclusive, false);
>>    	if (r)
>>    		return r;
>>    
>> -	p->num_dw_left = ndw;
>> -	return 0;
>> +	return amdgpu_sync_resv(p->adev, &p->job->sync, root->tbo.resv,
>> +				owner, false);
>>    }
>>    
>>    /**
>> @@ -99,13 +99,21 @@ static int amdgpu_vm_sdma_commit(struct amdgpu_vm_update_params *p,
>>    	struct dma_fence *f;
>>    	int r;
>>    
>> -	ring = container_of(p->vm->entity.rq->sched, struct amdgpu_ring, sched);
>> +	if (p->direct)
>> +		ring = p->adev->vm_manager.page_fault;
>> +	else
>> +		ring = container_of(p->vm->entity.rq->sched,
>> +				    struct amdgpu_ring, sched);
>>    
>>    	WARN_ON(ib->length_dw == 0);
>>    	amdgpu_ring_pad_ib(ring, ib);
>>    	WARN_ON(ib->length_dw > p->num_dw_left);
>> -	r = amdgpu_job_submit(p->job, &p->vm->entity,
>> -			      AMDGPU_FENCE_OWNER_VM, &f);
>> +
>> +	if (p->direct)
>> +		r = amdgpu_job_submit_direct(p->job, ring, &f);
> When we use direct submission after intialization, we need to take care
> of ring race condision, don't we? Am I missing anything?

Direct submission can only used by the page fault worker thread. And at 
least for now there is exactly one worker thread.

Christian.

>
>
> -David
>
>> +	else
>> +		r = amdgpu_job_submit(p->job, &p->vm->entity,
>> +				      AMDGPU_FENCE_OWNER_VM, &f);
>>    	if (r)
>>    		goto error;
>>    
>> @@ -120,7 +128,6 @@ static int amdgpu_vm_sdma_commit(struct amdgpu_vm_update_params *p,
>>    	return r;
>>    }
>>    
>> -
>>    /**
>>     * amdgpu_vm_sdma_copy_ptes - copy the PTEs from mapping
>>     *