[PATCH] amdgpu: fix multi-process hang issue

[Christian König]

Am 20.08.2018 um 05:35 schrieb Emily Deng:
> From: Monk Liu <Monk.Liu at amd.com>
>
> SWDEV-146499: hang during multi vulkan process testing
>
> cause:
> the second frame's PREAMBLE_IB have clear-state
> and LOAD actions, those actions ruin the pipeline
> that is still doing process in the previous frame's
> work-load IB.
>
> fix:
> need insert pipeline sync if have context switch for
> SRIOV (because only SRIOV will report PREEMPTION flag
> to UMD)
>
> Change-Id: If676da7a9b0147114cd76d19b6035ed8033de449
> Signed-off-by: Monk Liu <Monk.Liu at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c | 15 +++++++++++----
>   1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
> index 5c22cfd..66efa85 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
> @@ -95,6 +95,12 @@ void amdgpu_ib_free(struct amdgpu_device *adev, struct amdgpu_ib *ib,
>   	amdgpu_sa_bo_free(adev, &ib->sa_bo, f);
>   }
>   
> +static bool amdgpu_ib_has_preamble(struct amdgpu_ring *ring, bool ctx_switch) {
> +	return (amdgpu_sriov_vf(ring->adev) &&
> +			ring->funcs->type == AMDGPU_RING_TYPE_GFX &&
> +			ctx_switch);
> +}
> +

Well NAK, please merge that into amdgpu_ib_schedule() and drop the extra 
check for GFX, that will apply to compute queues as well.

>   /**
>    * amdgpu_ib_schedule - schedule an IB (Indirect Buffer) on the ring
>    *
> @@ -123,7 +129,7 @@ int amdgpu_ib_schedule(struct amdgpu_ring *ring, unsigned num_ibs,
>   	struct amdgpu_device *adev = ring->adev;
>   	struct amdgpu_ib *ib = &ibs[0];
>   	struct dma_fence *tmp = NULL;
> -	bool skip_preamble, need_ctx_switch;
> +	bool need_ctx_switch;
>   	unsigned patch_offset = ~0;
>   	struct amdgpu_vm *vm;
>   	uint64_t fence_ctx;
> @@ -156,6 +162,8 @@ int amdgpu_ib_schedule(struct amdgpu_ring *ring, unsigned num_ibs,
>   		return -EINVAL;
>   	}
>   
> +	need_ctx_switch = ring->current_ctx != fence_ctx;
> +
>   	alloc_size = ring->funcs->emit_frame_size + num_ibs *
>   		ring->funcs->emit_ib_size;
>   
> @@ -167,6 +175,7 @@ int amdgpu_ib_schedule(struct amdgpu_ring *ring, unsigned num_ibs,
>   
>   	if (ring->funcs->emit_pipeline_sync && job &&
>   	    ((tmp = amdgpu_sync_get_fence(&job->sched_sync, NULL)) ||
> +		 amdgpu_ib_has_preamble(ring, need_ctx_switch) ||
>   	     amdgpu_vm_need_pipeline_sync(ring, job))) {
>   		need_pipe_sync = true;
>   
> @@ -200,8 +209,6 @@ int amdgpu_ib_schedule(struct amdgpu_ring *ring, unsigned num_ibs,
>   			amdgpu_asic_flush_hdp(adev, ring);
>   	}
>   
> -	skip_preamble = ring->current_ctx == fence_ctx;
> -	need_ctx_switch = ring->current_ctx != fence_ctx;
>   	if (job && ring->funcs->emit_cntxcntl) {
>   		if (need_ctx_switch)
>   			status |= AMDGPU_HAVE_CTX_SWITCH;
> @@ -215,7 +222,7 @@ int amdgpu_ib_schedule(struct amdgpu_ring *ring, unsigned num_ibs,
>   
>   		/* drop preamble IBs if we don't have a context switch */
>   		if ((ib->flags & AMDGPU_IB_FLAG_PREAMBLE) &&
> -			skip_preamble &&
> +			!need_ctx_switch &&
>   			!(status & AMDGPU_PREAMBLE_IB_PRESENT_FIRST) &&
>   			!amdgpu_sriov_vf(adev)) /* for SRIOV preemption, Preamble CE ib must be inserted anyway */

Ok, please clean that up more carefully. All prerequisites which are not 
IB dependent should come before the loop.

BTW: The handling of AMDGPU_PREAMBLE_IB_PRESENT_FIRST in amdgpu_cs.c is 
completely broken as well.

Regards,
Christian.

>   			continue;