From fdfed8609dc555ca96022f185d32f2268479688b Mon Sep 17 00:00:00 2001 From: Himal Prasad Ghimiray Date: Thu, 1 Oct 2026 09:06:07 +0530 Subject: [PATCH] drm/xe: Bump prefetch BO LRU for already-valid ranges A valid prefetch range skips migration and binding, so nothing refreshes its backing BOs on the LRU. Add xe_svm_range_prefetch_lru_bump(), which re-faults with no_dma_map and bumps each backing BO, and call it on the valid path. v2 - Make function failsafe (Matt/Sashiko AI comment) - Add stub for function Suggested-by: Matthew Brost Reviewed-by: Matthew Brost Link: https://patch.msgid.link/20261001033602.3166274-10-himal.prasad.ghimiray@intel.com Signed-off-by: Himal Prasad Ghimiray Signed-off-by: Rodrigo Vivi --- drivers/gpu/drm/xe/xe_svm.c | 34 ++++++++++++++++++++++++++++++++++ drivers/gpu/drm/xe/xe_svm.h | 11 +++++++++++ drivers/gpu/drm/xe/xe_vm.c | 5 +++++ 3 files changed, 50 insertions(+) diff --git a/drivers/gpu/drm/xe/xe_svm.c b/drivers/gpu/drm/xe/xe_svm.c index d07dd95ab451..909a602d091e 100644 --- a/drivers/gpu/drm/xe/xe_svm.c +++ b/drivers/gpu/drm/xe/xe_svm.c @@ -1659,6 +1659,40 @@ void xe_svm_devmem_lru_bump(struct drm_pagemap_devmem *devmem_allocation) #endif } +/** + * xe_svm_range_prefetch_lru_bump() - Bump the TTM LRU for an already-valid range + * @vm: Pointer to the struct xe_vm + * @vma: Pointer to the VMA covering the range + * @range: Pointer to the xe SVM range structure + * @dpagemap: Target pagemap of the prefetch, or %NULL for system memory + * + * A valid range skips migration and binding, so nothing else refreshes its + * backing BOs on the LRU. Re-fault the CPU pages without touching the DMA + * mappings (@no_dma_map) and move each backing BO to the LRU tail. + * + * Prefetching is a best-effort optimization, so any failure is ignored; a + * later fault will refault the range. + */ +void xe_svm_range_prefetch_lru_bump(struct xe_vm *vm, struct xe_vma *vma, + struct xe_svm_range *range, + struct drm_pagemap *dpagemap) +{ + struct drm_gpusvm_ctx ctx = { + .read_only = xe_vma_read_only(vma), + .device_private_page_owner = + xe_svm_private_page_owner(vm, !dpagemap), + .no_dma_map = 1, + .devmem_fn = xe_svm_devmem_lru_bump, + }; + + guard(mutex)(&range->lock); + + if (xe_svm_range_is_removed(range)) + return; + + xe_svm_range_get_pages(vm, range, &ctx); +} + /** * xe_svm_ranges_zap_ptes_in_range - clear ptes of svm ranges in input range * @vm: Pointer to the xe_vm structure diff --git a/drivers/gpu/drm/xe/xe_svm.h b/drivers/gpu/drm/xe/xe_svm.h index 585ad64b672b..ffc1cc808102 100644 --- a/drivers/gpu/drm/xe/xe_svm.h +++ b/drivers/gpu/drm/xe/xe_svm.h @@ -130,6 +130,10 @@ int xe_svm_range_get_pages(struct xe_vm *vm, struct xe_svm_range *range, void xe_svm_devmem_lru_bump(struct drm_pagemap_devmem *devmem_allocation); +void xe_svm_range_prefetch_lru_bump(struct xe_vm *vm, struct xe_vma *vma, + struct xe_svm_range *range, + struct drm_pagemap *dpagemap); + bool xe_svm_range_needs_migrate_to_vram(struct xe_svm_range *range, struct xe_vma *vma, const struct drm_pagemap *dpagemap); @@ -363,6 +367,13 @@ void xe_svm_devmem_lru_bump(struct drm_pagemap_devmem *devmem_allocation) { } +static inline +void xe_svm_range_prefetch_lru_bump(struct xe_vm *vm, struct xe_vma *vma, + struct xe_svm_range *range, + struct drm_pagemap *dpagemap) +{ +} + static inline struct xe_svm_range *to_xe_range(struct drm_gpusvm_range *r) { return NULL; diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c index 986e0ebfdacd..3842a5f332ab 100644 --- a/drivers/gpu/drm/xe/xe_vm.c +++ b/drivers/gpu/drm/xe/xe_vm.c @@ -2570,6 +2570,11 @@ vm_bind_ioctl_ops_create(struct xe_vm *vm, struct xe_vma_ops *vops, dpagemap, &valid_pages)) { xe_svm_range_debug(svm_range, "PREFETCH - RANGE IS VALID"); xe_assert(vm->xe, valid_pages); + + if (dpagemap) + xe_svm_range_prefetch_lru_bump(vm, vma, svm_range, + dpagemap); + need_put = true; goto check_next_range; }