[PATCH 09/15] drm/xe: Convert the CPU fault handler for exhaustive eviction

[Matthew Brost]

On Wed, Aug 13, 2025 at 12:51:15PM +0200, Thomas Hellström wrote:
> The CPU fault handler may populate bos and migrate, and in doing
> so might interfere with other tasks validing.
> 
> Convert it for exhaustive eviction. To do this properly without
> potentially introducing stalls with the mmap lock held requires
> TTM work. In the meantime, let's live with those stalls that
> would typically happen on memory pressure.
> 
> Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
> ---
>  drivers/gpu/drm/xe/xe_bo.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
> index 5e40b6cb8d2a..dd1e0e9957e0 100644
> --- a/drivers/gpu/drm/xe/xe_bo.c
> +++ b/drivers/gpu/drm/xe/xe_bo.c
> @@ -1720,14 +1720,18 @@ static vm_fault_t xe_gem_fault(struct vm_fault *vmf)
>  	struct xe_device *xe = to_xe_device(ddev);
>  	struct xe_bo *bo = ttm_to_xe_bo(tbo);
>  	bool needs_rpm = bo->flags & XE_BO_FLAG_VRAM_MASK;
> -	struct drm_exec *exec;
> +	struct xe_validation_ctx ctx;
> +	struct drm_exec exec;
>  	vm_fault_t ret;
>  	int idx;
>  
>  	if (needs_rpm)
>  		xe_pm_runtime_get(xe);
>  
> -	exec = XE_VALIDATION_UNIMPLEMENTED;
> +	if (xe_validation_ctx_init(&ctx, &xe->val, &exec,
> +				   DRM_EXEC_INTERRUPTIBLE_WAIT, 0, false))
> +		return VM_FAULT_NOPAGE;

Any particular reason to not use xe_validation_guard here?

Matt

> +
>  	ret = ttm_bo_vm_reserve(tbo, vmf);
>  	if (ret)
>  		goto out;
> @@ -1735,7 +1739,7 @@ static vm_fault_t xe_gem_fault(struct vm_fault *vmf)
>  	if (drm_dev_enter(ddev, &idx)) {
>  		trace_xe_bo_cpu_fault(bo);
>  
> -		xe_validation_assert_exec(xe, exec, &tbo->base);
> +		xe_validation_assert_exec(xe, &exec, &tbo->base);
>  		ret = ttm_bo_vm_fault_reserved(vmf, vmf->vma->vm_page_prot,
>  					       TTM_BO_VM_NUM_PREFAULT);
>  		drm_dev_exit(idx);
> @@ -1761,6 +1765,7 @@ static vm_fault_t xe_gem_fault(struct vm_fault *vmf)
>  
>  	dma_resv_unlock(tbo->base.resv);
>  out:
> +	xe_validation_ctx_fini(&ctx);
>  	if (needs_rpm)
>  		xe_pm_runtime_put(xe);
>  
> -- 
> 2.50.1
>