Re: [RFC PATCH 1/4] drm/amdkfd: Improve amdgpu_vm_handle_moved

[Christian König <christian.koenig@xxxxxxx>]

Am 17.03.22 um 01:20 schrieb Felix Kuehling:
> Let amdgpu_vm_handle_moved update all BO VA mappings of BOs reserved by
> the caller. This will be useful for handling extra BO VA mappings in
> KFD VMs that are managed through the render node API.

Yes, that change is on my TODO list for quite a while as well.

> TODO: This may also allow simplification of amdgpu_cs_vm_handling. See
> the TODO comment in the code.

No, that won't work just yet.

We need to change the TLB flush detection for that, but I'm already 
working on those as well.

> Signed-off-by: Felix Kuehling <Felix.Kuehling@xxxxxxx>

Please update the TODO, with that done: Reviewed-by: Christian König 
<christian.koenig@xxxxxxx>

> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c      |  6 +++++-
>   drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c |  2 +-
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c      | 18 +++++++++++++-----
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h      |  3 ++-
>   4 files changed, 21 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> index d162243d8e78..10941f0d8dde 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> @@ -826,6 +826,10 @@ static int amdgpu_cs_vm_handling(struct amdgpu_cs_parser *p)
>   			return r;
>   	}
>   
> +	/* TODO: Is this loop still needed, or could this be handled by
> +	 * amdgpu_vm_handle_moved, now that it can handle all BOs that are
> +	 * reserved under p->ticket?
> +	 */
>   	amdgpu_bo_list_for_each_entry(e, p->bo_list) {
>   		/* ignore duplicates */
>   		bo = ttm_to_amdgpu_bo(e->tv.bo);
> @@ -845,7 +849,7 @@ static int amdgpu_cs_vm_handling(struct amdgpu_cs_parser *p)
>   			return r;
>   	}
>   
> -	r = amdgpu_vm_handle_moved(adev, vm);
> +	r = amdgpu_vm_handle_moved(adev, vm, &p->ticket);
>   	if (r)
>   		return r;
>   
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
> index 579adfafe4d0..50805613c38c 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
> @@ -414,7 +414,7 @@ amdgpu_dma_buf_move_notify(struct dma_buf_attachment *attach)
>   
>   		r = amdgpu_vm_clear_freed(adev, vm, NULL);
>   		if (!r)
> -			r = amdgpu_vm_handle_moved(adev, vm);
> +			r = amdgpu_vm_handle_moved(adev, vm, ticket);
>   
>   		if (r && r != -EBUSY)
>   			DRM_ERROR("Failed to invalidate VM page tables (%d))\n",
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> index fc4563cf2828..726b42c6d606 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> @@ -2190,11 +2190,12 @@ int amdgpu_vm_clear_freed(struct amdgpu_device *adev,
>    * PTs have to be reserved!
>    */
>   int amdgpu_vm_handle_moved(struct amdgpu_device *adev,
> -			   struct amdgpu_vm *vm)
> +			   struct amdgpu_vm *vm,
> +			   struct ww_acquire_ctx *ticket)
>   {
>   	struct amdgpu_bo_va *bo_va, *tmp;
>   	struct dma_resv *resv;
> -	bool clear;
> +	bool clear, unlock;
>   	int r;
>   
>   	list_for_each_entry_safe(bo_va, tmp, &vm->moved, base.vm_status) {
> @@ -2212,17 +2213,24 @@ int amdgpu_vm_handle_moved(struct amdgpu_device *adev,
>   		spin_unlock(&vm->invalidated_lock);
>   
>   		/* Try to reserve the BO to avoid clearing its ptes */
> -		if (!amdgpu_vm_debug && dma_resv_trylock(resv))
> +		if (!amdgpu_vm_debug && dma_resv_trylock(resv)) {
>   			clear = false;
> +			unlock = true;
> +		/* The caller is already holding the reservation lock */
> +		} else if (ticket && dma_resv_locking_ctx(resv) == ticket) {
> +			clear = false;
> +			unlock = false;
>   		/* Somebody else is using the BO right now */
> -		else
> +		} else {
>   			clear = true;
> +			unlock = false;
> +		}
>   
>   		r = amdgpu_vm_bo_update(adev, bo_va, clear, NULL);
>   		if (r)
>   			return r;
>   
> -		if (!clear)
> +		if (unlock)
>   			dma_resv_unlock(resv);
>   		spin_lock(&vm->invalidated_lock);
>   	}
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
> index a40a6a993bb0..120a76aaae75 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
> @@ -396,7 +396,8 @@ int amdgpu_vm_clear_freed(struct amdgpu_device *adev,
>   			  struct amdgpu_vm *vm,
>   			  struct dma_fence **fence);
>   int amdgpu_vm_handle_moved(struct amdgpu_device *adev,
> -			   struct amdgpu_vm *vm);
> +			   struct amdgpu_vm *vm,
> +			   struct ww_acquire_ctx *ticket);
>   int amdgpu_vm_bo_update_mapping(struct amdgpu_device *adev,
>   				struct amdgpu_device *bo_adev,
>   				struct amdgpu_vm *vm, bool immediate,