Re: [PATCH v3] drm/amdkfd: Use partial mapping in GPU page faults

[Philip Yang <yangp@xxxxxxx>]

On 2023-10-20 17:53, Xiaogang.Chen wrote:

> From: Xiaogang Chen <xiaogang.chen@xxxxxxx>
>
> After partial migration to recover GPU page fault this patch does GPU vm
> space mapping for same page range that got migrated intead of mapping all
> pages of svm range in which the page fault happened.
>
> Signed-off-by: Xiaogang Chen<Xiaogang.Chen@xxxxxxx>
>     
    Reviewed-by: Philip Yang<Philip.Yang@xxxxxxx>
> ---
>  drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 29 ++++++++++++++++++++--------
>  1 file changed, 21 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> index 54af7a2b29f8..3a71d04779b1 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> @@ -1619,6 +1619,7 @@ static void *kfd_svm_page_owner(struct kfd_process *p, int32_t gpuidx)
>   * 5. Release page table (and SVM BO) reservation
>   */
>  static int svm_range_validate_and_map(struct mm_struct *mm,
> +				      unsigned long map_start, unsigned long map_last,
>  				      struct svm_range *prange, int32_t gpuidx,
>  				      bool intr, bool wait, bool flush_tlb)
>  {
> @@ -1699,6 +1700,8 @@ static int svm_range_validate_and_map(struct mm_struct *mm,
>  	end = (prange->last + 1) << PAGE_SHIFT;
>  	for (addr = start; !r && addr < end; ) {
>  		struct hmm_range *hmm_range;
> +		unsigned long map_start_vma;
> +		unsigned long map_last_vma;
>  		struct vm_area_struct *vma;
>  		uint64_t vram_pages_vma;
>  		unsigned long next = 0;
> @@ -1747,9 +1750,16 @@ static int svm_range_validate_and_map(struct mm_struct *mm,
>  			r = -EAGAIN;
>  		}
>  
> -		if (!r)
> -			r = svm_range_map_to_gpus(prange, offset, npages, readonly,
> -						  ctx->bitmap, wait, flush_tlb);
> +		if (!r) {
> +			map_start_vma = max(map_start, prange->start + offset);
> +			map_last_vma = min(map_last, prange->start + offset + npages - 1);
> +			if (map_start_vma <= map_last_vma) {
> +				offset = map_start_vma - prange->start;
> +				npages = map_last_vma - map_start_vma + 1;
> +				r = svm_range_map_to_gpus(prange, offset, npages, readonly,
> +							  ctx->bitmap, wait, flush_tlb);
> +			}
> +		}
>  
>  		if (!r && next == end)
>  			prange->mapped_to_gpu = true;
> @@ -1855,8 +1865,8 @@ static void svm_range_restore_work(struct work_struct *work)
>  		 */
>  		mutex_lock(&prange->migrate_mutex);
>  
> -		r = svm_range_validate_and_map(mm, prange, MAX_GPU_INSTANCE,
> -					       false, true, false);
> +		r = svm_range_validate_and_map(mm, prange->start, prange->last, prange,
> +					       MAX_GPU_INSTANCE, false, true, false);
>  		if (r)
>  			pr_debug("failed %d to map 0x%lx to gpus\n", r,
>  				 prange->start);
> @@ -3069,6 +3079,8 @@ svm_range_restore_pages(struct amdgpu_device *adev, unsigned int pasid,
>  	kfd_smi_event_page_fault_start(node, p->lead_thread->pid, addr,
>  				       write_fault, timestamp);
>  
> +	start = prange->start;
> +	last = prange->last;
>  	if (prange->actual_loc != 0 || best_loc != 0) {
>  		migration = true;
>  		/* Align migration range start and size to granularity size */
> @@ -3102,10 +3114,11 @@ svm_range_restore_pages(struct amdgpu_device *adev, unsigned int pasid,
>  		}
>  	}
>  
> -	r = svm_range_validate_and_map(mm, prange, gpuidx, false, false, false);
> +	r = svm_range_validate_and_map(mm, start, last, prange, gpuidx, false,
> +				       false, false);
>  	if (r)
>  		pr_debug("failed %d to map svms 0x%p [0x%lx 0x%lx] to gpus\n",
> -			 r, svms, prange->start, prange->last);
> +			 r, svms, start, last);
>  
>  	kfd_smi_event_page_fault_end(node, p->lead_thread->pid, addr,
>  				     migration);
> @@ -3650,7 +3663,7 @@ svm_range_set_attr(struct kfd_process *p, struct mm_struct *mm,
>  
>  		flush_tlb = !migrated && update_mapping && prange->mapped_to_gpu;
>  
> -		r = svm_range_validate_and_map(mm, prange, MAX_GPU_INSTANCE,
> +		r = svm_range_validate_and_map(mm, prange->start, prange->last, prange, MAX_GPU_INSTANCE,
>  					       true, true, flush_tlb);
>  		if (r)
>  			pr_debug("failed %d to map svm range\n", r);
>