Re: [RFC PATCH 1/3] drm/amdgpu: Add vm->notifier_lock

[Christian König <christian.koenig@xxxxxxx>]

Am 21.12.22 um 00:27 schrieb Felix Kuehling:
> This points to a mutex to serialize with MMU notifiers during page table
> updates. For graphics contexts, the notifier lock is per adev. For compute
> contexts the lock is per process.
I don't think mixing the VM code into this is a good idea. Instead we 
should expose the lock function to code outside of the VM subsystem.

Regards,
Christian.

> Signed-off-by: Felix Kuehling <Felix.Kuehling@xxxxxxx>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 3 +++
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c           | 1 +
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h           | 3 +++
>   3 files changed, 7 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> index b15091d8310d..7aaa844a8284 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> @@ -1325,9 +1325,12 @@ static int init_kfd_vm(struct amdgpu_vm *vm, void **process_info,
>   
>   		*process_info = info;
>   		*ef = dma_fence_get(&info->eviction_fence->base);
> +	} else {
> +		info = *process_info;
>   	}
>   
>   	vm->process_info = *process_info;
> +	vm->notifier_lock = &info->notifier_lock;
>   
>   	/* Validate page directory and attach eviction fence */
>   	ret = amdgpu_bo_reserve(vm->root.bo, true);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> index dc379dc22c77..a04f7aef4ca9 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> @@ -2075,6 +2075,7 @@ int amdgpu_vm_init(struct amdgpu_device *adev, struct amdgpu_vm *vm)
>   
>   	mutex_init(&vm->eviction_lock);
>   	vm->evicting = false;
> +	vm->notifier_lock = &adev->notifier_lock;
>   
>   	r = amdgpu_vm_pt_create(adev, vm, adev->vm_manager.root_level,
>   				false, &root);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
> index 094bb4807303..07af80df812b 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
> @@ -251,6 +251,9 @@ struct amdgpu_vm {
>   	bool			evicting;
>   	unsigned int		saved_flags;
>   
> +	/* Pointer to notifier lock used when updating PTEs */
> +	struct mutex		*notifier_lock;
> +
>   	/* Lock to protect vm_bo add/del/move on all lists of vm */
>   	spinlock_t		status_lock;
>