[PATCH v5 23/25] drm/xe: Reset VMA attributes to default in SVM garbage collector
Ghimiray, Himal Prasad
himal.prasad.ghimiray at intel.com
Wed Aug 6 05:32:12 UTC 2025
On 06-08-2025 09:36, Matthew Brost wrote:
> On Wed, Jul 30, 2025 at 06:30:48PM +0530, Himal Prasad Ghimiray wrote:
>> Restore default memory attributes for VMAs during garbage collection
>> if they were modified by madvise. Reuse existing VMA if fully overlapping;
>> otherwise, allocate a new mirror VMA.
>>
>> v2 (Matthew Brost)
>> - Add helper for vma split
>> - Add retry to get updated vma
>>
>> Suggested-by: Matthew Brost <matthew.brost at intel.com>
>> Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray at intel.com>
>> ---
>> drivers/gpu/drm/xe/xe_svm.c | 114 +++++++++++++++++++++-----
>> drivers/gpu/drm/xe/xe_vm.c | 155 ++++++++++++++++++++++++++----------
>> drivers/gpu/drm/xe/xe_vm.h | 2 +
>> 3 files changed, 206 insertions(+), 65 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/xe/xe_svm.c b/drivers/gpu/drm/xe/xe_svm.c
>> index aef76e08b460..9b3a3f61758c 100644
>> --- a/drivers/gpu/drm/xe/xe_svm.c
>> +++ b/drivers/gpu/drm/xe/xe_svm.c
>> @@ -253,9 +253,55 @@ static int __xe_svm_garbage_collector(struct xe_vm *vm,
>> return 0;
>> }
>>
>> +static int xe_svm_range_set_default_attr(struct xe_vm *vm, u64 range_start, u64 range_end)
>> +{
>> + struct xe_vma *vma;
>> + struct xe_vma_mem_attr default_attr = {
>> + .preferred_loc = {
>> + .devmem_fd = DRM_XE_PREFERRED_LOC_DEFAULT_DEVICE,
>> + .migration_policy = DRM_XE_MIGRATE_ALL_PAGES,
>> + },
>> + .atomic_access = DRM_XE_ATOMIC_UNDEFINED,
>> + };
>> + int err = 0;
>> +
>> + vma = xe_vm_find_vma_by_addr(vm, range_start);
>> + if (!vma)
>> + return -EINVAL;
>> +
>> + if (xe_vma_has_default_mem_attrs(vma))
>> + return 0;
>> +
>> + vm_dbg(&vm->xe->drm, "Existing VMA start=0x%016llx, vma_end=0x%016llx",
>> + xe_vma_start(vma), xe_vma_end(vma));
>> +
>> + if (xe_vma_start(vma) == range_start && xe_vma_end(vma) == range_end) {
>> + default_attr.pat_index = vma->attr.default_pat_index;
>> + default_attr.default_pat_index = vma->attr.default_pat_index;
>> + vma->attr = default_attr;
>> + } else {
>> + vm_dbg(&vm->xe->drm, "Split VMA start=0x%016llx, vma_end=0x%016llx",
>> + range_start, range_end);
>> + err = xe_vm_alloc_cpu_addr_mirror_vma(vm, range_start, range_end - range_start);
>> + if (err) {
>> + drm_warn(&vm->xe->drm, "VMA SPLIT failed: %pe\n", ERR_PTR(err));
>> + xe_vm_kill(vm, true);
>> + return err;
>> + }
>> + }
>> +
>> + /*
>> + * On call from xe_svm_handle_pagefault original VMA might be changed
>> + * signal this to lookup for VMA again.
>> + */
>> + return -EAGAIN;
>> +}
>> +
>> static int xe_svm_garbage_collector(struct xe_vm *vm)
>> {
>> struct xe_svm_range *range;
>> + u64 range_start;
>> + u64 range_end;
>> int err;
>>
>> lockdep_assert_held_write(&vm->lock);
>> @@ -271,6 +317,9 @@ static int xe_svm_garbage_collector(struct xe_vm *vm)
>> if (!range)
>> break;
>>
>> + range_start = xe_svm_range_start(range);
>> + range_end = xe_svm_range_end(range);
>> +
>> list_del(&range->garbage_collector_link);
>> spin_unlock(&vm->svm.garbage_collector.lock);
>>
>> @@ -283,6 +332,10 @@ static int xe_svm_garbage_collector(struct xe_vm *vm)
>> return err;
>> }
>>
>> + err = xe_svm_range_set_default_attr(vm, range_start, range_end);
>> + if (err)
>> + return err;
>
> You don't want to return on -EAGAIN here, rather collect it, continue
> and return -EAGAIN once the garbage collector list is empty. No need to
> contiously lookup the VMA in xe_svm_handle_pagefault (in next rev
> __xe_svm_handle_pagefault), this only need be done once.
True. makes sense.
>
>> +
>> spin_lock(&vm->svm.garbage_collector.lock);
>> }
>> spin_unlock(&vm->svm.garbage_collector.lock);
>> @@ -793,40 +846,59 @@ int xe_svm_handle_pagefault(struct xe_vm *vm, struct xe_vma *vma,
>> struct xe_gt *gt, u64 fault_addr,
>> bool atomic)
>> {
>> - int need_vram = xe_vma_need_vram_for_atomic(vm->xe, vma, atomic);
>> -
>> - if (need_vram < 0)
>> - return need_vram;
>> -
>> - struct drm_gpusvm_ctx ctx = {
>> - .read_only = xe_vma_read_only(vma),
>> - .devmem_possible = IS_DGFX(vm->xe) &&
>> - IS_ENABLED(CONFIG_DRM_XE_PAGEMAP),
>> - .check_pages_threshold = IS_DGFX(vm->xe) &&
>> - IS_ENABLED(CONFIG_DRM_XE_PAGEMAP) ? SZ_64K : 0,
>> - .devmem_only = need_vram && IS_ENABLED(CONFIG_DRM_XE_PAGEMAP),
>> - .timeslice_ms = atomic && IS_DGFX(vm->xe) &&
>> - IS_ENABLED(CONFIG_DRM_XE_PAGEMAP) ?
>> - vm->xe->atomic_svm_timeslice_ms : 0,
>> - };
>> + struct drm_gpusvm_ctx ctx = { };
>> + struct drm_pagemap *dpagemap;
>> struct xe_svm_range *range;
>> 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;
>> + bool vma_updated = false;
>> + int need_vram;
>> + int migrate_try_count;
>> ktime_t end = 0;
>> int err;
>>
>> - lockdep_assert_held_write(&vm->lock);
>> +find_vma:
>> + if (vma_updated) {
>> + vma = xe_vm_find_vma_by_addr(vm, fault_addr);
>> + if (!vma)
>> + return -EINVAL;
>> + }
>> +
>> xe_assert(vm->xe, xe_vma_is_cpu_addr_mirror(vma));
>> + vma_updated = false;
>> +
>> + need_vram = xe_vma_need_vram_for_atomic(vm->xe, vma, atomic);
>> + if (need_vram < 0)
>> + return need_vram;
>
> This is a bit ugly. I think if you have __xe_svm_handle_pagefault and
> xe_svm_handle_pagefault as here [1] this can be handled cleaner (i.e.
> still a static setup of drm_gpusvm_ctx).
>
> If xe_svm_garbage_collector returns an in __xe_svm_handle_pagefault kick
> it up to xe_svm_handle_pagefault, you catch -EAGAIN there, relookup the
> VMA and call __xe_svm_handle_pagefault again. I think that would look
> quite a bit better.
Agreed. Will update in next version.
Thanks>
> Matt
>
> [1] https://patchwork.freedesktop.org/patch/666222/?series=149550&rev=5#comment_1222471
>
>> +
>> + ctx.read_only = xe_vma_read_only(vma);
>> + ctx.devmem_possible = IS_DGFX(vm->xe) && IS_ENABLED(CONFIG_DRM_XE_PAGEMAP);
>> + ctx.check_pages_threshold = IS_DGFX(vm->xe) && IS_ENABLED(CONFIG_DRM_XE_PAGEMAP) ?
>> + SZ_64K : 0;
>> + ctx.devmem_only = need_vram && IS_ENABLED(CONFIG_DRM_XE_PAGEMAP);
>> + ctx.timeslice_ms = atomic && IS_DGFX(vm->xe) && IS_ENABLED(CONFIG_DRM_XE_PAGEMAP) ?
>> + vm->xe->atomic_svm_timeslice_ms : 0;
>>
>> + migrate_try_count = ctx.devmem_only ? 3 : 1;
>> +
>> + lockdep_assert_held_write(&vm->lock);
>> xe_gt_stats_incr(gt, XE_GT_STATS_ID_SVM_PAGEFAULT_COUNT, 1);
>>
>> retry:
>> /* Always process UNMAPs first so view SVM ranges is current */
>> err = xe_svm_garbage_collector(vm);
>> - if (err)
>> - return err;
>> + if (err) {
>> + if (err == -EAGAIN) {
>> + /*
>> + * VMA might have changed due to garbage
>> + * collection; retry lookup
>> + */
>> + vma_updated = true;
>> + goto find_vma;
>> + } else {
>> + return err;
>> + }
>> + }
>>
>> range = xe_svm_range_find_or_insert(vm, fault_addr, vma, &ctx);
>>
>> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
>> index 5ee38e9cf6c6..e77c04f92d0b 100644
>> --- a/drivers/gpu/drm/xe/xe_vm.c
>> +++ b/drivers/gpu/drm/xe/xe_vm.c
>> @@ -4263,36 +4263,24 @@ int xe_vma_need_vram_for_atomic(struct xe_device *xe, struct xe_vma *vma, bool i
>> }
>> }
>>
>> -/**
>> - * xe_vm_alloc_madvise_vma - Allocate VMA's with madvise ops
>> - * @vm: Pointer to the xe_vm structure
>> - * @start: Starting input address
>> - * @range: Size of the input range
>> - *
>> - * This function splits existing vma to create new vma for user provided input range
>> - *
>> - * Return: 0 if success
>> - */
>> -int xe_vm_alloc_madvise_vma(struct xe_vm *vm, uint64_t start, uint64_t range)
>> +static int xe_vm_alloc_vma(struct xe_vm *vm, struct drm_gpuva_op_map *map_req)
>> {
>> - struct drm_gpuva_op_map map_req = {
>> - .va.addr = start,
>> - .va.range = range,
>> - .flags = DRM_GPUVM_SM_MAP_OPS_FLAG_SPLIT_MADVISE,
>> - };
>> -
>> struct xe_vma_ops vops;
>> struct drm_gpuva_ops *ops = NULL;
>> struct drm_gpuva_op *__op;
>> bool is_cpu_addr_mirror = false;
>> bool remap_op = false;
>> + bool is_madvise = (map_req->flags & DRM_GPUVM_SM_MAP_OPS_FLAG_SPLIT_MADVISE);
>> struct xe_vma_mem_attr tmp_attr;
>> + u16 default_pat;
>> int err;
>>
>> lockdep_assert_held_write(&vm->lock);
>>
>> - vm_dbg(&vm->xe->drm, "MADVISE_OPS_CREATE: addr=0x%016llx, size=0x%016llx", start, range);
>> - ops = drm_gpuvm_sm_map_ops_create(&vm->gpuvm, &map_req);
>> + vm_dbg(&vm->xe->drm, "MADVISE_OPS_CREATE: addr=0x%016llx, size=0x%016llx",
>> + map_req->va.addr, map_req->va.range);
>> +
>> + ops = drm_gpuvm_sm_map_ops_create(&vm->gpuvm, map_req);
>> if (IS_ERR(ops))
>> return PTR_ERR(ops);
>>
>> @@ -4303,33 +4291,56 @@ int xe_vm_alloc_madvise_vma(struct xe_vm *vm, uint64_t start, uint64_t range)
>>
>> drm_gpuva_for_each_op(__op, ops) {
>> struct xe_vma_op *op = gpuva_op_to_vma_op(__op);
>> + struct xe_vma *vma = NULL;
>>
>> - if (__op->op == DRM_GPUVA_OP_REMAP) {
>> - xe_assert(vm->xe, !remap_op);
>> - remap_op = true;
>> + if (!is_madvise) {
>> + if (__op->op == DRM_GPUVA_OP_UNMAP) {
>> + vma = gpuva_to_vma(op->base.unmap.va);
>> + XE_WARN_ON(!xe_vma_has_default_mem_attrs(vma));
>> + default_pat = vma->attr.default_pat_index;
>> + }
>>
>> - if (xe_vma_is_cpu_addr_mirror(gpuva_to_vma(op->base.remap.unmap->va)))
>> - is_cpu_addr_mirror = true;
>> - else
>> - is_cpu_addr_mirror = false;
>> - }
>> + if (__op->op == DRM_GPUVA_OP_REMAP) {
>> + vma = gpuva_to_vma(op->base.remap.unmap->va);
>> + default_pat = vma->attr.default_pat_index;
>> + }
>>
>> - if (__op->op == DRM_GPUVA_OP_MAP) {
>> - xe_assert(vm->xe, remap_op);
>> - remap_op = false;
>> + if (__op->op == DRM_GPUVA_OP_MAP) {
>> + op->map.is_cpu_addr_mirror = true;
>> + op->map.pat_index = default_pat;
>> + }
>> + } else {
>> + if (__op->op == DRM_GPUVA_OP_REMAP) {
>> + vma = gpuva_to_vma(op->base.remap.unmap->va);
>> + xe_assert(vm->xe, !remap_op);
>> + remap_op = true;
>>
>> - /* In case of madvise ops DRM_GPUVA_OP_MAP is always after
>> - * DRM_GPUVA_OP_REMAP, so ensure we assign op->map.is_cpu_addr_mirror true
>> - * if REMAP is for xe_vma_is_cpu_addr_mirror vma
>> - */
>> - op->map.is_cpu_addr_mirror = is_cpu_addr_mirror;
>> - }
>> + if (xe_vma_is_cpu_addr_mirror(vma))
>> + is_cpu_addr_mirror = true;
>> + else
>> + is_cpu_addr_mirror = false;
>> + }
>>
>> + if (__op->op == DRM_GPUVA_OP_MAP) {
>> + xe_assert(vm->xe, remap_op);
>> + remap_op = false;
>> + /*
>> + * In case of madvise ops DRM_GPUVA_OP_MAP is
>> + * always after DRM_GPUVA_OP_REMAP, so ensure
>> + * we assign op->map.is_cpu_addr_mirror true
>> + * if REMAP is for xe_vma_is_cpu_addr_mirror vma
>> + */
>> + op->map.is_cpu_addr_mirror = is_cpu_addr_mirror;
>> + }
>> + }
>> print_op(vm->xe, __op);
>> }
>>
>> xe_vma_ops_init(&vops, vm, NULL, NULL, 0);
>> - vops.flags |= XE_VMA_OPS_FLAG_MADVISE;
>> +
>> + if (is_madvise)
>> + vops.flags |= XE_VMA_OPS_FLAG_MADVISE;
>> +
>> err = vm_bind_ioctl_ops_parse(vm, ops, &vops);
>> if (err)
>> goto unwind_ops;
>> @@ -4341,15 +4352,20 @@ int xe_vm_alloc_madvise_vma(struct xe_vm *vm, uint64_t start, uint64_t range)
>> struct xe_vma *vma;
>>
>> if (__op->op == DRM_GPUVA_OP_UNMAP) {
>> - /* There should be no unmap */
>> - XE_WARN_ON("UNEXPECTED UNMAP");
>> - xe_vma_destroy(gpuva_to_vma(op->base.unmap.va), NULL);
>> + vma = gpuva_to_vma(op->base.unmap.va);
>> + /* There should be no unmap for madvise */
>> + if (is_madvise)
>> + XE_WARN_ON("UNEXPECTED UNMAP");
>> +
>> + xe_vma_destroy(vma, NULL);
>> } else if (__op->op == DRM_GPUVA_OP_REMAP) {
>> vma = gpuva_to_vma(op->base.remap.unmap->va);
>> - /* Store attributes for REMAP UNMAPPED VMA, so they can be assigned
>> - * to newly MAP created vma.
>> + /* In case of madvise ops Store attributes for REMAP UNMAPPED
>> + * VMA, so they can be assigned to newly MAP created vma.
>> */
>> - tmp_attr = vma->attr;
>> + if (is_madvise)
>> + tmp_attr = vma->attr;
>> +
>> xe_vma_destroy(gpuva_to_vma(op->base.remap.unmap->va), NULL);
>> } else if (__op->op == DRM_GPUVA_OP_MAP) {
>> vma = op->map.vma;
>> @@ -4357,7 +4373,8 @@ int xe_vm_alloc_madvise_vma(struct xe_vm *vm, uint64_t start, uint64_t range)
>> * Therefore temp_attr will always have sane values, making it safe to
>> * copy them to new vma.
>> */
>> - vma->attr = tmp_attr;
>> + if (is_madvise)
>> + vma->attr = tmp_attr;
>> }
>> }
>>
>> @@ -4371,3 +4388,53 @@ int xe_vm_alloc_madvise_vma(struct xe_vm *vm, uint64_t start, uint64_t range)
>> drm_gpuva_ops_free(&vm->gpuvm, ops);
>> return err;
>> }
>> +
>> +/**
>> + * xe_vm_alloc_madvise_vma - Allocate VMA's with madvise ops
>> + * @vm: Pointer to the xe_vm structure
>> + * @start: Starting input address
>> + * @range: Size of the input range
>> + *
>> + * This function splits existing vma to create new vma for user provided input range
>> + *
>> + * Return: 0 if success
>> + */
>> +int xe_vm_alloc_madvise_vma(struct xe_vm *vm, uint64_t start, uint64_t range)
>> +{
>> + struct drm_gpuva_op_map map_req = {
>> + .va.addr = start,
>> + .va.range = range,
>> + .flags = DRM_GPUVM_SM_MAP_OPS_FLAG_SPLIT_MADVISE,
>> + };
>> +
>> + lockdep_assert_held_write(&vm->lock);
>> +
>> + vm_dbg(&vm->xe->drm, "MADVISE_OPS_CREATE: addr=0x%016llx, size=0x%016llx", start, range);
>> +
>> + return xe_vm_alloc_vma(vm, &map_req);
>> +}
>> +
>> +/**
>> + * xe_vm_alloc_cpu_addr_mirror_vma - Allocate CPU addr mirror vma
>> + * @vm: Pointer to the xe_vm structure
>> + * @start: Starting input address
>> + * @range: Size of the input range
>> + *
>> + * This function splits/merges existing vma to create new vma for user provided input range
>> + *
>> + * Return: 0 if success
>> + */
>> +int xe_vm_alloc_cpu_addr_mirror_vma(struct xe_vm *vm, uint64_t start, uint64_t range)
>> +{
>> + struct drm_gpuva_op_map map_req = {
>> + .va.addr = start,
>> + .va.range = range,
>> + };
>> +
>> + lockdep_assert_held_write(&vm->lock);
>> +
>> + vm_dbg(&vm->xe->drm, "CPU_ADDR_MIRROR_VMA_OPS_CREATE: addr=0x%016llx, size=0x%016llx",
>> + start, range);
>> +
>> + return xe_vm_alloc_vma(vm, &map_req);
>> +}
>> diff --git a/drivers/gpu/drm/xe/xe_vm.h b/drivers/gpu/drm/xe/xe_vm.h
>> index f735d994806d..6538cddf158b 100644
>> --- a/drivers/gpu/drm/xe/xe_vm.h
>> +++ b/drivers/gpu/drm/xe/xe_vm.h
>> @@ -177,6 +177,8 @@ int xe_vma_need_vram_for_atomic(struct xe_device *xe, struct xe_vma *vma, bool i
>>
>> int xe_vm_alloc_madvise_vma(struct xe_vm *vm, uint64_t addr, uint64_t size);
>>
>> +int xe_vm_alloc_cpu_addr_mirror_vma(struct xe_vm *vm, uint64_t addr, uint64_t size);
>> +
>> /**
>> * to_userptr_vma() - Return a pointer to an embedding userptr vma
>> * @vma: Pointer to the embedded struct xe_vma
>> --
>> 2.34.1
>>
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