[PATCH v3 13/19] drm/xe/madvise: Update migration policy based on preferred location
Matthew Brost
matthew.brost at intel.com
Thu May 29 23:42:42 UTC 2025
On Tue, May 27, 2025 at 10:09:57PM +0530, Himal Prasad Ghimiray wrote:
> When the user sets the valid devmem_fd as a preferred location, GPU fault
> will trigger migration to tile of device associated with devmem_fd.
>
> If the user sets an invalid devmem_fd the preferred location is current
> placement(smem) only.
>
> v2(Matthew Brost)
> - Default should be faulting tile
> - remove devmem_fd used as region
>
> Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray at intel.com>
> ---
> drivers/gpu/drm/xe/xe_svm.c | 39 +++++++++++++++++++++++++++++-
> drivers/gpu/drm/xe/xe_svm.h | 8 ++++++
> drivers/gpu/drm/xe/xe_vm.h | 3 +++
> drivers/gpu/drm/xe/xe_vm_madvise.c | 15 +++++++++++-
> 4 files changed, 63 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_svm.c b/drivers/gpu/drm/xe/xe_svm.c
> index 743bb1f7d39c..8b6546ebac72 100644
> --- a/drivers/gpu/drm/xe/xe_svm.c
> +++ b/drivers/gpu/drm/xe/xe_svm.c
> @@ -791,6 +791,37 @@ bool xe_svm_range_needs_migrate_to_vram(struct xe_svm_range *range, struct xe_vm
> return true;
> }
>
> +/**
> + * xe_vma_resolve_pagemap - Resolve the appropriate DRM pagemap for a VMA
> + * @vma: Pointer to the xe_vma structure containing memory attributes
> + * @tile: Pointer to the xe_tile structure used as fallback for VRAM mapping
> + *
> + * This function determines the correct DRM pagemap to use for a given VMA.
> + * It first checks if a valid devmem_fd is provided in the VMA's preferred
> + * location. If the devmem_fd is negative, it returns NULL, indicating no
> + * pagemap is available and smem to be used as preferred location.
> + * If the devmem_fd is equal to the default faulting
> + * GT identifier, it returns the VRAM pagemap associated with the tile.
> + *
> + * Future support for multi-device configurations may use drm_pagemap_from_fd()
> + * to resolve pagemaps from arbitrary file descriptors.
> + *
> + * Return: A pointer to the resolved drm_pagemap, or NULL if none is applicable.
> + */
> +struct drm_pagemap *xe_vma_resolve_pagemap(struct xe_vma *vma, struct xe_tile *tile)
> +{
> + s32 fd = (s32)vma->attr.preferred_loc.devmem_fd;
> +
> + if (fd < 0)
> + return NULL;
> +
> + if (fd == DRM_XE_PREFERRED_LOC_DEFAULT_DEVMEM_FD && tile)
> + return &tile->mem.vram.dpagemap;
I'd change this here to:
return IS_DGFX(xe) ? return &tile->mem.vram.dpagemap : NULL;
> +
> + /* TODO: Support multi-device with drm_pagemap_from_fd(fd) */
> + return NULL;
> +}
> +
> /**
> * xe_svm_handle_pagefault() - SVM handle page fault
> * @vm: The VM.
> @@ -823,6 +854,7 @@ int xe_svm_handle_pagefault(struct xe_vm *vm, struct xe_vma *vma,
> struct xe_svm_range *range;
> struct drm_exec exec;
> struct dma_fence *fence;
> + struct drm_pagemap *dpagemap;
> struct xe_tile *tile = gt_to_tile(gt);
> int migrate_try_count = ctx.devmem_only ? 3 : 1;
> ktime_t end = 0;
> @@ -852,8 +884,13 @@ int xe_svm_handle_pagefault(struct xe_vm *vm, struct xe_vma *vma,
>
> range_debug(range, "PAGE FAULT");
>
> + dpagemap = xe_vma_resolve_pagemap(vma, tile);
> if (--migrate_try_count >= 0 &&
> - xe_svm_range_needs_migrate_to_vram(range, vma, IS_DGFX(vm->xe))) {
> + xe_svm_range_needs_migrate_to_vram(range, vma, IS_DGFX(vm->xe) && !!dpagemap)) {
See my comment in patch 12 + comment above, I think this condition should be:
!!dpagemap || (atomic && xe_vma_need_vram_migrate_for_atomic)
> + /* 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.
> + */
> err = xe_svm_alloc_vram(vm, tile, range, &ctx);
> ctx.timeslice_ms <<= 1; /* Double timeslice if we have to retry */
> if (err) {
> diff --git a/drivers/gpu/drm/xe/xe_svm.h b/drivers/gpu/drm/xe/xe_svm.h
> index b36f70ab3d03..344349313001 100644
> --- a/drivers/gpu/drm/xe/xe_svm.h
> +++ b/drivers/gpu/drm/xe/xe_svm.h
> @@ -95,6 +95,8 @@ u8 xe_svm_ranges_zap_ptes_in_range(struct xe_vm *vm, u64 start, u64 end);
>
> void xe_svm_range_clean_if_addr_within(struct xe_vm *vm, u64 start, u64 end);
>
> +struct drm_pagemap *xe_vma_resolve_pagemap(struct xe_vma *vma, struct xe_tile *tile);
> +
> /**
> * xe_svm_range_has_dma_mapping() - SVM range has DMA mapping
> * @range: SVM range
> @@ -320,6 +322,12 @@ void xe_svm_range_clean_if_addr_within(struct xe_vm *vm, u64 start, u64 end)
> {
> }
>
> +static inline
> +struct drm_pagemap *xe_vma_resolve_pagemap(struct xe_vma *vma, struct xe_tile *tile)
> +{
> + return NULL;
> +}
> +
> #define xe_svm_assert_in_notifier(...) do {} while (0)
> #define xe_svm_range_has_dma_mapping(...) false
>
> diff --git a/drivers/gpu/drm/xe/xe_vm.h b/drivers/gpu/drm/xe/xe_vm.h
> index edd6ffd7c3ac..340ac34936f4 100644
> --- a/drivers/gpu/drm/xe/xe_vm.h
> +++ b/drivers/gpu/drm/xe/xe_vm.h
> @@ -222,6 +222,9 @@ int __xe_vm_userptr_needs_repin(struct xe_vm *vm);
>
> int xe_vm_userptr_check_repin(struct xe_vm *vm);
>
> +bool xe_vma_has_preferred_mem_loc(struct xe_vma *vma,
> + u32 *mem_region, u32 *devmem_fd);
> +
> int xe_vm_rebind(struct xe_vm *vm, bool rebind_worker);
> struct dma_fence *xe_vma_rebind(struct xe_vm *vm, struct xe_vma *vma,
> u8 tile_mask);
> diff --git a/drivers/gpu/drm/xe/xe_vm_madvise.c b/drivers/gpu/drm/xe/xe_vm_madvise.c
> index 084719660401..1b31e41b3331 100644
> --- a/drivers/gpu/drm/xe/xe_vm_madvise.c
> +++ b/drivers/gpu/drm/xe/xe_vm_madvise.c
> @@ -61,7 +61,20 @@ static int madvise_preferred_mem_loc(struct xe_device *xe, struct xe_vm *vm,
> struct xe_vma **vmas, int num_vmas,
> struct drm_xe_madvise_ops ops)
> {
> - /* Implementation pending */
> + int i;
> +
> + xe_assert(vm->xe, ops.type == DRM_XE_VMA_ATTR_PREFERRED_LOC);
> +
> + for (i = 0; i < num_vmas; i++) {
> + vmas[i]->attr.preferred_loc.devmem_fd = ops.preferred_mem_loc.devmem_fd;
> +
> + /* Till multi-device support is not added migration_policy
> + * is of no use and can be ignored.
> + */
> + //vmas[i]->attr.preferred_loc.migration_policy =
> + // ops.preferred_mem_loc.migration_policy;
No harm in just setting this for now and remaning unused, right?
Matt
> + }
> +
> return 0;
> }
>
> --
> 2.34.1
>
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