Re: [PATCH 10/15] drm/xe: Use the vma attibute drm_pagemap to select where to migrate

["Thomas Hellström" <thomas.hellstrom@linux.intel.com>]

On Tue, 2025-10-28 at 20:27 -0700, Matthew Brost wrote:
> On Sat, Oct 25, 2025 at 02:04:07PM +0200, Thomas Hellström wrote:
> > Enable migrating to foreign drm_pagemaps.
> > 
> 
> Slightly better commit message ahead of merging.
> 
> > Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> > ---
> >  drivers/gpu/drm/xe/xe_svm.c      | 39 +++++++++++++++-------------
> > ----
> >  drivers/gpu/drm/xe/xe_svm.h      |  8 +++----
> >  drivers/gpu/drm/xe/xe_vm.c       | 19 ++++++----------
> >  drivers/gpu/drm/xe/xe_vm_types.h |  6 ++---
> >  4 files changed, 32 insertions(+), 40 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/xe/xe_svm.c
> > b/drivers/gpu/drm/xe/xe_svm.c
> > index d27cedeaf70c..36a6ac293e71 100644
> > --- a/drivers/gpu/drm/xe/xe_svm.c
> > +++ b/drivers/gpu/drm/xe/xe_svm.c
> > @@ -1132,9 +1132,9 @@ static int __xe_svm_handle_pagefault(struct
> > xe_vm *vm, struct xe_vma *vma,
> >  	if (err)
> >  		return err;
> >  
> > -	dpagemap = xe_vma_resolve_pagemap(vma, tile);
> > -	ctx.device_private_page_owner =
> > -		xe_svm_private_page_owner(vm, !dpagemap &&
> > !ctx.devmem_only);
> > +	dpagemap = ctx.devmem_only ? xe_tile_local_pagemap(tile) :
> > +		xe_vma_resolve_pagemap(vma, tile);
> > +	ctx.device_private_page_owner =
> > xe_svm_private_page_owner(vm, !dpagemap);
> >  	range = xe_svm_range_find_or_insert(vm, fault_addr, vma,
> > &ctx);
> >  
> >  	if (IS_ERR(range))
> > @@ -1159,13 +1159,8 @@ static int __xe_svm_handle_pagefault(struct
> > xe_vm *vm, struct xe_vma *vma,
> >  	    xe_svm_range_needs_migrate_to_vram(range, vma,
> > !!dpagemap || ctx.devmem_only)) {
> >  		ktime_t migrate_start = xe_svm_stats_ktime_get();
> >  
> > -		/* TODO : For multi-device dpagemap will be used
> > to find the
> > -		 * remote tile and remote device. Will need to
> > modify
> > -		 * xe_svm_alloc_vram to use dpagemap for future
> > multi-device
> > -		 * support.
> > -		 */
> >  		xe_svm_range_migrate_count_stats_incr(gt, range);
> > -		err = xe_svm_alloc_vram(tile, range, &ctx);
> > +		err = xe_svm_alloc_vram(range, &ctx, dpagemap);
> >  		xe_svm_range_migrate_us_stats_incr(gt, range,
> > migrate_start);
> >  		ctx.timeslice_ms <<= 1;	/* Double
> > timeslice if we have to retry */
> >  		if (err) {
> > @@ -1482,7 +1477,13 @@ u8 xe_svm_ranges_zap_ptes_in_range(struct
> > xe_vm *vm, u64 start, u64 end)
> >   */
> >  struct drm_pagemap *xe_vma_resolve_pagemap(struct xe_vma *vma,
> > struct xe_tile *tile)
> >  {
> > -	s32 fd = (s32)vma->attr.preferred_loc.devmem_fd;
> > +	struct drm_pagemap *dpagemap = vma-
> > >attr.preferred_loc.dpagemap;
> > +	s32 fd;
> > +
> > +	if (dpagemap)
> > +		return dpagemap;
> > +
> > +	fd = (s32)vma->attr.preferred_loc.devmem_fd;
> >  
> >  	if (fd == DRM_XE_PREFERRED_LOC_DEFAULT_SYSTEM)
> >  		return NULL;
> > @@ -1490,28 +1491,24 @@ struct drm_pagemap
> > *xe_vma_resolve_pagemap(struct xe_vma *vma, struct xe_tile *t
> >  	if (fd == DRM_XE_PREFERRED_LOC_DEFAULT_DEVICE)
> >  		return IS_DGFX(tile_to_xe(tile)) ?
> > xe_tile_local_pagemap(tile) : NULL;
> >  
> > -	/* TODO: Support multi-device with drm_pagemap_from_fd(fd)
> > */
> >  	return NULL;
> >  }
> >  
> >  /**
> >   * xe_svm_alloc_vram()- Allocate device memory pages for range,
> >   * migrating existing data.
> > - * @tile: tile to allocate vram from
> >   * @range: SVM range
> >   * @ctx: DRM GPU SVM context
> > + * @dpagemap: The struct drm_pagemap representing the memory to
> > allocate.
> >   *
> >   * Return: 0 on success, error code on failure.
> >   */
> > -int xe_svm_alloc_vram(struct xe_tile *tile, struct xe_svm_range
> > *range,
> > -		      const struct drm_gpusvm_ctx *ctx)
> > +int xe_svm_alloc_vram(struct xe_svm_range *range, const struct
> > drm_gpusvm_ctx *ctx,
> > +		      struct drm_pagemap *dpagemap)
> >  {
> > -	struct drm_pagemap *dpagemap;
> > -
> > -	xe_assert(tile_to_xe(tile), range-
> > >base.pages.flags.migrate_devmem);
> > +	xe_assert(range_to_vm(&range->base)->xe, range-
> > >base.pages.flags.migrate_devmem);
> >  	range_debug(range, "ALLOCATE VRAM");
> >  
> > -	dpagemap = xe_tile_local_pagemap(tile);
> >  	return drm_pagemap_populate_mm(dpagemap,
> > xe_svm_range_start(range),
> >  				       xe_svm_range_end(range),
> >  				       range->base.gpusvm->mm,
> > @@ -1778,9 +1775,9 @@ int xe_pagemap_cache_create(struct xe_tile
> > *tile)
> >  	return 0;
> >  }
> >  
> > -int xe_svm_alloc_vram(struct xe_tile *tile,
> > -		      struct xe_svm_range *range,
> > -		      const struct drm_gpusvm_ctx *ctx)
> > +int xe_svm_alloc_vram(struct xe_svm_range *range,
> > +		      const struct drm_gpusvm_ctx *ctx,
> > +		      struct drm_pagemap *dpagemap)
> >  {
> >  	return -EOPNOTSUPP;
> >  }
> > diff --git a/drivers/gpu/drm/xe/xe_svm.h
> > b/drivers/gpu/drm/xe/xe_svm.h
> > index 5adce108f7eb..c7027facf6e9 100644
> > --- a/drivers/gpu/drm/xe/xe_svm.h
> > +++ b/drivers/gpu/drm/xe/xe_svm.h
> > @@ -94,8 +94,8 @@ int xe_svm_bo_evict(struct xe_bo *bo);
> >  
> >  void xe_svm_range_debug(struct xe_svm_range *range, const char
> > *operation);
> >  
> > -int xe_svm_alloc_vram(struct xe_tile *tile, struct xe_svm_range
> > *range,
> > -		      const struct drm_gpusvm_ctx *ctx);
> > +int xe_svm_alloc_vram(struct xe_svm_range *range, const struct
> > drm_gpusvm_ctx *ctx,
> > +		      struct drm_pagemap *dpagemap);
> >  
> >  struct xe_svm_range *xe_svm_range_find_or_insert(struct xe_vm *vm,
> > u64 addr,
> >  						 struct xe_vma
> > *vma, struct drm_gpusvm_ctx *ctx);
> > @@ -276,8 +276,8 @@ void xe_svm_range_debug(struct xe_svm_range
> > *range, const char *operation)
> >  }
> >  
> >  static inline int
> > -xe_svm_alloc_vram(struct xe_tile *tile, struct xe_svm_range
> > *range,
> > -		  const struct drm_gpusvm_ctx *ctx)
> > +xe_svm_alloc_vram(struct xe_svm_range *range, const struct
> > drm_gpusvm_ctx *ctx,
> > +		  struct drm_pagemap *dpagemap)
> >  {
> >  	return -EOPNOTSUPP;
> >  }
> > diff --git a/drivers/gpu/drm/xe/xe_vm.c
> > b/drivers/gpu/drm/xe/xe_vm.c
> > index 3c3dc1b1ace9..381d4b4abac9 100644
> > --- a/drivers/gpu/drm/xe/xe_vm.c
> > +++ b/drivers/gpu/drm/xe/xe_vm.c
> > @@ -2355,18 +2355,13 @@ vm_bind_ioctl_ops_create(struct xe_vm *vm,
> > struct xe_vma_ops *vops,
> >  			if (prefetch_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 if (prefetch_region) {
> >  				tile = &vm->xe-
> > >tiles[region_to_mem_type[prefetch_region] -
> >  						     
> > XE_PL_VRAM0];
> > +				dpagemap =
> > xe_tile_local_pagemap(tile);
> 
> Per kernel test robot, dpagemap needs to initialized to NULL. There
> is
> existing code which tile to NULL after a for_each_tile loop that can
> also be droppped.
> 

Yeah I noticed that. I'll fix this up.
Thanks,
Thomas


> Everything else looks right.

> 
> Matt
> 
> >  			}
> >  
> > -			op->prefetch_range.tile = tile;
> > +			op->prefetch_range.dpagemap = dpagemap;
> >  alloc_next_range:
> >  			svm_range =
> > xe_svm_range_find_or_insert(vm, addr, vma, &ctx);
> >  
> > @@ -2897,7 +2892,7 @@ static int prefetch_ranges(struct xe_vm *vm,
> > struct xe_vma_op *op)
> >  {
> >  	bool devmem_possible = IS_DGFX(vm->xe) &&
> > IS_ENABLED(CONFIG_DRM_XE_PAGEMAP);
> >  	struct xe_vma *vma = gpuva_to_vma(op->base.prefetch.va);
> > -	struct xe_tile *tile = op->prefetch_range.tile;
> > +	struct drm_pagemap *dpagemap = op-
> > >prefetch_range.dpagemap;
> >  	int err = 0;
> >  
> >  	struct xe_svm_range *svm_range;
> > @@ -2910,15 +2905,15 @@ static int prefetch_ranges(struct xe_vm
> > *vm, struct xe_vma_op *op)
> >  	ctx.read_only = xe_vma_read_only(vma);
> >  	ctx.devmem_possible = devmem_possible;
> >  	ctx.check_pages_threshold = devmem_possible ? SZ_64K : 0;
> > -	ctx.device_private_page_owner =
> > xe_svm_private_page_owner(vm, !tile);
> > +	ctx.device_private_page_owner =
> > xe_svm_private_page_owner(vm, !dpagemap);
> >  
> >  	/* TODO: Threading the migration */
> >  	xa_for_each(&op->prefetch_range.range, i, svm_range) {
> > -		if (!tile)
> > +		if (!dpagemap)
> >  			xe_svm_range_migrate_to_smem(vm,
> > svm_range);
> >  
> > -		if (xe_svm_range_needs_migrate_to_vram(svm_range,
> > vma, !!tile)) {
> > -			err = xe_svm_alloc_vram(tile, svm_range,
> > &ctx);
> > +		if (xe_svm_range_needs_migrate_to_vram(svm_range,
> > vma, !!dpagemap)) {
> > +			err = xe_svm_alloc_vram(svm_range, &ctx,
> > dpagemap);
> >  			if (err) {
> >  				drm_dbg(&vm->xe->drm, "VRAM
> > allocation failed, retry from userspace, asid=%u, gpusvm=%p,
> > errno=%pe\n",
> >  					vm->usm.asid, &vm-
> > >svm.gpusvm, ERR_PTR(err));
> > diff --git a/drivers/gpu/drm/xe/xe_vm_types.h
> > b/drivers/gpu/drm/xe/xe_vm_types.h
> > index 70856d536047..5313bf2afa54 100644
> > --- a/drivers/gpu/drm/xe/xe_vm_types.h
> > +++ b/drivers/gpu/drm/xe/xe_vm_types.h
> > @@ -413,10 +413,10 @@ struct xe_vma_op_prefetch_range {
> >  	/** @ranges_count: number of svm ranges to map */
> >  	u32 ranges_count;
> >  	/**
> > -	 * @tile: Pointer to the tile structure containing memory
> > to prefetch.
> > -	 *        NULL if prefetch requested region is smem
> > +	 * @dpagemap: Pointer to the dpagemap structure containing
> > memory to prefetch.
> > +	 * NULL if prefetch requested region is smem
> >  	 */
> > -	struct xe_tile *tile;
> > +	struct drm_pagemap *dpagemap;
> >  };
> >  
> >  /** enum xe_vma_op_flags - flags for VMA operation */
> > -- 
> > 2.51.0
> >