[PATCH v6 19/26] drm/xe/svm: Consult madvise preferred location in prefetch

[Matthew Brost]

On Thu, Aug 07, 2025 at 10:13:31PM +0530, Himal Prasad Ghimiray wrote:
> When prefetch region is DRM_XE_CONSULT_MEM_ADVISE_PREF_LOC, prefetch svm
> ranges to preferred location provided by madvise.
> 
> v2 (Matthew Brost)
> - Fix region, devmem_fd usages
> - consult madvise is applicable for other vma's too.
> 
> v3
> - Fix atomic handling
> 
> Cc: Matthew Brost <matthew.brost at intel.com>
> Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray at intel.com>
> Reviewed-by: Matthew Brost <matthew.brost at intel.com>
> ---
>  drivers/gpu/drm/xe/xe_vm.c | 30 ++++++++++++++++++++++--------
>  1 file changed, 22 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> index aa8d4c4fe0f0..ae966755255d 100644
> --- a/drivers/gpu/drm/xe/xe_vm.c
> +++ b/drivers/gpu/drm/xe/xe_vm.c
> @@ -38,6 +38,7 @@
>  #include "xe_res_cursor.h"
>  #include "xe_svm.h"
>  #include "xe_sync.h"
> +#include "xe_tile.h"
>  #include "xe_trace_bo.h"
>  #include "xe_wa.h"
>  #include "xe_hmm.h"
> @@ -2913,15 +2914,28 @@ static int prefetch_ranges(struct xe_vm *vm, struct xe_vma_op *op)
>  	int err = 0;
>  
>  	struct xe_svm_range *svm_range;
> +	struct drm_pagemap *dpagemap;
>  	struct drm_gpusvm_ctx ctx = {};
> -	struct xe_tile *tile;
> +	struct xe_tile *tile = NULL;
>  	unsigned long i;
>  	u32 region;
>  
>  	if (!xe_vma_is_cpu_addr_mirror(vma))
>  		return 0;
>  
> -	region = op->prefetch_range.region;
> +	if (op->prefetch_range.region == DRM_XE_CONSULT_MEM_ADVISE_PREF_LOC) {
> +		dpagemap = xe_vma_resolve_pagemap(vma, xe_device_get_root_tile(vm->xe));
> +		/*
> +		 * TODO: Once multigpu support is enabled will need
> +		 * something to dereference tile from dpagemap.
> +		 */
> +		if (dpagemap)
> +			tile = xe_device_get_root_tile(vm->xe);
> +	} else {
> +		region = op->prefetch_range.region;
> +		if (region)
> +			tile = &vm->xe->tiles[region_to_mem_type[region] - XE_PL_VRAM0];
> +	}

You need similar logic in vm_bind_ioctl_ops_create ahead of
xe_svm_range_validate.

Maybe pull this out into a helper for do this calculation there and
stick the result in the op which could be used here.

Matt

>  
>  	ctx.read_only = xe_vma_read_only(vma);
>  	ctx.devmem_possible = devmem_possible;
> @@ -2929,11 +2943,10 @@ static int prefetch_ranges(struct xe_vm *vm, struct xe_vma_op *op)
>  
>  	/* TODO: Threading the migration */
>  	xa_for_each(&op->prefetch_range.range, i, svm_range) {
> -		if (!region)
> +		if (!tile)
>  			xe_svm_range_migrate_to_smem(vm, svm_range);
>  
> -		if (xe_svm_range_needs_migrate_to_vram(svm_range, vma, region)) {
> -			tile = &vm->xe->tiles[region_to_mem_type[region] - XE_PL_VRAM0];
> +		if (xe_svm_range_needs_migrate_to_vram(svm_range, vma, !!tile)) {
>  			err = xe_svm_alloc_vram(tile, svm_range, &ctx);
>  			if (err) {
>  				drm_dbg(&vm->xe->drm, "VRAM allocation failed, retry from userspace, asid=%u, gpusvm=%p, errno=%pe\n",
> @@ -3001,7 +3014,8 @@ static int op_lock_and_prep(struct drm_exec *exec, struct xe_vm *vm,
>  		else
>  			region = op->prefetch.region;
>  
> -		xe_assert(vm->xe, region <= ARRAY_SIZE(region_to_mem_type));
> +		xe_assert(vm->xe, region == DRM_XE_CONSULT_MEM_ADVISE_PREF_LOC ||
> +			  region <= ARRAY_SIZE(region_to_mem_type));
>  
>  		err = vma_lock_and_validate(exec,
>  					    gpuva_to_vma(op->base.prefetch.va),
> @@ -3419,8 +3433,8 @@ static int vm_bind_ioctl_check_args(struct xe_device *xe, struct xe_vm *vm,
>  				 op == DRM_XE_VM_BIND_OP_PREFETCH) ||
>  		    XE_IOCTL_DBG(xe, prefetch_region &&
>  				 op != DRM_XE_VM_BIND_OP_PREFETCH) ||
> -		    XE_IOCTL_DBG(xe, !(BIT(prefetch_region) &
> -				       xe->info.mem_region_mask)) ||
> +		    XE_IOCTL_DBG(xe,  (prefetch_region != DRM_XE_CONSULT_MEM_ADVISE_PREF_LOC &&
> +				       !(BIT(prefetch_region) & xe->info.mem_region_mask))) ||
>  		    XE_IOCTL_DBG(xe, obj &&
>  				 op == DRM_XE_VM_BIND_OP_UNMAP)) {
>  			err = -EINVAL;
> -- 
> 2.34.1
>