Re: [RFC 3/5] drm/xe: have xe_svm_range embed one drm_gpusvm_pages

Wed, 10 Jun 2026 02:03:30 -0700 



On 6/10/2026 12:14 PM, Matthew Brost wrote:

On Wed, Jun 03, 2026 at 02:56:18PM +0800, Honglei Huang wrote:

From: Honglei Huang <[email protected]>

With drm_gpusvm_pages now self contained, make xe stop relying
on the drm_gpusvm_range pages and take responsibility for the page
lifecycle on the driver side.

Driver side (xe):

   - Embed struct drm_gpusvm_pages in xe_svm_range and route all
     xe accesses through it instead of range->base.pages.
   - Take over the page lifecycle: xe_svm_range_get_pages() calls
     drm_gpusvm_get_pages() directly with &xe->drm; the notifier
     event_end and xe_svm_range_free() paths drive unmap/free on
     the embedded pages object.
   - Switch xe_svm_range_pages_valid() to drm_gpusvm_pages_valid().

Framework side (drm_gpusvm):

   - Export drm_gpusvm_pages_valid() to let driver owned pages
     can query mapping state without going through a range.
   - Contract change: drm_gpusvm_range_remove() no longer unmaps or
     frees pages; drivers that own a drm_gpusvm_pages instance must
     do that themselves.

Side effect / contract: drivers that own a drm_gpusvm_pages
are now responsible for its lifecycle, in particular for calling
drm_gpusvm_unmap_pages() and drm_gpusvm_free_pages() at the
appropriate points.

Suggested-by: Matthew Brost <[email protected]>
Signed-off-by: Honglei Huang <[email protected]>
---
  drivers/gpu/drm/drm_gpusvm.c |  9 +++------
  drivers/gpu/drm/xe/xe_pt.c   |  2 +-
  drivers/gpu/drm/xe/xe_svm.c  | 22 +++++++++++++++-------
  drivers/gpu/drm/xe/xe_svm.h  |  9 +++++++--
  include/drm/drm_gpusvm.h     |  3 +++
  5 files changed, 29 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/drm_gpusvm.c b/drivers/gpu/drm/drm_gpusvm.c
index 3f076178b2a..a4b56cefeb2 100644
--- a/drivers/gpu/drm/drm_gpusvm.c
+++ b/drivers/gpu/drm/drm_gpusvm.c
@@ -1231,8 +1231,6 @@ EXPORT_SYMBOL_GPL(drm_gpusvm_free_pages);
  void drm_gpusvm_range_remove(struct drm_gpusvm *gpusvm,
                             struct drm_gpusvm_range *range)
  {
-       unsigned long npages = npages_in_range(drm_gpusvm_range_start(range),
-                                              drm_gpusvm_range_end(range));
        struct drm_gpusvm_notifier *notifier;

  
  	drm_gpusvm_driver_lock_held(gpusvm);

@@ -1244,8 +1242,6 @@ void drm_gpusvm_range_remove(struct drm_gpusvm *gpusvm,
                return;

  
  	drm_gpusvm_notifier_lock(gpusvm);

-       __drm_gpusvm_unmap_pages(gpusvm, &range->pages, npages);
-       __drm_gpusvm_free_pages(gpusvm, &range->pages);
        __drm_gpusvm_range_remove(notifier, range);
        drm_gpusvm_notifier_unlock(gpusvm);

  
@@ -1324,13 +1320,14 @@ EXPORT_SYMBOL_GPL(drm_gpusvm_range_put);

   *
   * Return: True if GPU SVM range has valid pages, False otherwise
   */
-static bool drm_gpusvm_pages_valid(struct drm_gpusvm *gpusvm,
-                                  struct drm_gpusvm_pages *svm_pages)
+bool drm_gpusvm_pages_valid(struct drm_gpusvm *gpusvm,
+                           struct drm_gpusvm_pages *svm_pages)
  {
        lockdep_assert_held(&gpusvm->notifier_lock);

  
  	return svm_pages->flags.has_devmem_pages || svm_pages->flags.has_dma_mapping;

  }
+EXPORT_SYMBOL_GPL(drm_gpusvm_pages_valid);

  
  /**

   * drm_gpusvm_range_pages_valid() - GPU SVM range pages valid
diff --git a/drivers/gpu/drm/xe/xe_pt.c b/drivers/gpu/drm/xe/xe_pt.c
index 2669ff5ee74..e82b0d8fab1 100644
--- a/drivers/gpu/drm/xe/xe_pt.c
+++ b/drivers/gpu/drm/xe/xe_pt.c
@@ -758,7 +758,7 @@ xe_pt_stage_bind(struct xe_tile *tile, struct xe_vma *vma,
                        return -EAGAIN;
                }
                if (xe_svm_range_has_dma_mapping(range)) {
-                       xe_res_first_dma(range->base.pages.dma_addr, 0,
+                       xe_res_first_dma(range->pages.dma_addr, 0,
                                         xe_svm_range_size(range),
                                         &curs);
                        xe_svm_range_debug(range, "BIND PREPARE - MIXED");
diff --git a/drivers/gpu/drm/xe/xe_svm.c b/drivers/gpu/drm/xe/xe_svm.c
index 3acfddb7c5b..33c26df5111 100644
--- a/drivers/gpu/drm/xe/xe_svm.c
+++ b/drivers/gpu/drm/xe/xe_svm.c
@@ -66,7 +66,7 @@ static bool xe_svm_range_in_vram(struct xe_svm_range *range)

  
  	struct drm_gpusvm_pages_flags flags = {

                /* Pairs with WRITE_ONCE in drm_gpusvm.c */
-               .__flags = READ_ONCE(range->base.pages.flags.__flags),
+               .__flags = READ_ONCE(range->pages.flags.__flags),
        };

  
  	return flags.has_devmem_pages;

@@ -96,7 +96,7 @@ static struct xe_vm *range_to_vm(struct drm_gpusvm_range *r)
               (r__)->base.gpusvm,                                   \
               xe_svm_range_in_vram((r__)) ? 1 : 0,                     \
               xe_svm_range_has_vram_binding((r__)) ? 1 : 0,            \
-              (r__)->base.pages.notifier_seq,                               \
+              (r__)->pages.notifier_seq,                            \
               xe_svm_range_start((r__)), xe_svm_range_end((r__)),      \
               xe_svm_range_size((r__)))

  
@@ -115,6 +115,7 @@ xe_svm_range_alloc(struct drm_gpusvm *gpusvm)

                return NULL;

  
  	INIT_LIST_HEAD(&range->garbage_collector_link);

+       range->pages.notifier_seq = LONG_MAX;


As discussed in the cover-letter let's do a drm_gpusvm_init_pages()
function to set the notifier_seq.

If we want to include 'drm' in the init function as discussed in patch
#2, to fish this out in Xe you can do '&gpusvm_to_vm(gpusvm)->xe->drm'.



Got it, will init the seq in drm_gpusvm_init_pages, and will aplly the 
init in Xe according to your suggestion.






        xe_vm_get(gpusvm_to_vm(gpusvm));

  
  	return &range->base;

@@ -122,8 +123,10 @@ xe_svm_range_alloc(struct drm_gpusvm *gpusvm)

  
  static void xe_svm_range_free(struct drm_gpusvm_range *range)

  {
+       drm_gpusvm_free_pages(range->gpusvm, &(to_xe_range(range)->pages),
+                             drm_gpusvm_range_size(range) >> PAGE_SHIFT);
        xe_vm_put(range_to_vm(range));
-       kfree(range);
+       kfree(to_xe_range(range));
  }

  
  static void

@@ -208,7 +211,8 @@ xe_svm_range_notifier_event_end(struct xe_vm *vm, struct 
drm_gpusvm_range *r,

  
  	xe_svm_assert_in_notifier(vm);
  
-	drm_gpusvm_range_unmap_pages(&vm->svm.gpusvm, r, &ctx);

+       drm_gpusvm_unmap_pages(&vm->svm.gpusvm, &(to_xe_range(r)->pages),
+                              drm_gpusvm_range_size(r) >> PAGE_SHIFT, &ctx);
        if (!xe_vm_is_closed(vm) && mmu_range->event == MMU_NOTIFY_UNMAP)
                xe_svm_garbage_collector_add_range(vm, to_xe_range(r),
                                                   mmu_range);
@@ -952,7 +956,7 @@ void xe_svm_fini(struct xe_vm *vm)
  static bool xe_svm_range_has_pagemap_locked(const struct xe_svm_range *range,
                                            const struct drm_pagemap *dpagemap)
  {
-       return range->base.pages.dpagemap == dpagemap;
+       return range->pages.dpagemap == dpagemap;
  }

  
  static bool xe_svm_range_has_pagemap(struct xe_svm_range *range,

@@ -1017,7 +1021,7 @@ bool xe_svm_range_validate(struct xe_vm *vm,
        if (dpagemap)
                ret = ret && xe_svm_range_has_pagemap_locked(range, dpagemap);
        else
-               ret = ret && !range->base.pages.dpagemap;
+               ret = ret && !range->pages.dpagemap;

  
  	xe_svm_notifier_unlock(vm);
  
@@ -1510,7 +1514,11 @@ int xe_svm_range_get_pages(struct xe_vm *vm, struct xe_svm_range *range,

        if (READ_ONCE(range->base.flags.unmapped))
                return -EFAULT;

  
-	err = drm_gpusvm_range_get_pages(&vm->svm.gpusvm, &range->base, ctx);

+       err = drm_gpusvm_get_pages(&vm->svm.gpusvm, &range->pages,
+                                  &vm->xe->drm, vm->svm.gpusvm.mm,
+                                  &range->base.notifier->notifier,
+                                  drm_gpusvm_range_start(&range->base),
+                                  drm_gpusvm_range_end(&range->base), ctx);
        if (err == -EOPNOTSUPP) {
                range_debug(range, "PAGE FAULT - EVICT PAGES");
                drm_gpusvm_range_evict(&vm->svm.gpusvm, &range->base);
diff --git a/drivers/gpu/drm/xe/xe_svm.h b/drivers/gpu/drm/xe/xe_svm.h
index b7b8eeacf19..ea73241d3d9 100644
--- a/drivers/gpu/drm/xe/xe_svm.h
+++ b/drivers/gpu/drm/xe/xe_svm.h
@@ -31,6 +31,11 @@ struct xe_vram_region;
  struct xe_svm_range {
        /** @base: base drm_gpusvm_range */
        struct drm_gpusvm_range base;
+       /**
+        * @pages: Per-device DMA mapping state; single instance since
+        * xe svm is 1 svm : 1 drm_device.


s/xe/Xe


Got it, will fix.

Regards,
Honglei



Matt


+        */
+       struct drm_gpusvm_pages pages;
        /**
         * @garbage_collector_link: Link into VM's garbage collect SVM range
         * list. Protected by VM's garbage collect lock.
@@ -74,7 +79,7 @@ struct xe_pagemap {
   */
  static inline bool xe_svm_range_pages_valid(struct xe_svm_range *range)
  {
-       return drm_gpusvm_range_pages_valid(range->base.gpusvm, &range->base);
+       return drm_gpusvm_pages_valid(range->base.gpusvm, &range->pages);
  }

  
  int xe_devm_add(struct xe_tile *tile, struct xe_vram_region *vr);

@@ -132,7 +137,7 @@ void *xe_svm_private_page_owner(struct xe_vm *vm, bool 
force_smem);
  static inline bool xe_svm_range_has_dma_mapping(struct xe_svm_range *range)
  {
        lockdep_assert_held(&range->base.gpusvm->notifier_lock);
-       return range->base.pages.flags.has_dma_mapping;
+       return range->pages.flags.has_dma_mapping;
  }

  
  /**

diff --git a/include/drm/drm_gpusvm.h b/include/drm/drm_gpusvm.h
index ed228d9ff6b..21baf91ec7e 100644
--- a/include/drm/drm_gpusvm.h
+++ b/include/drm/drm_gpusvm.h
@@ -306,6 +306,9 @@ void drm_gpusvm_range_put(struct drm_gpusvm_range *range);
  bool drm_gpusvm_range_pages_valid(struct drm_gpusvm *gpusvm,
                                  struct drm_gpusvm_range *range);

  
+bool drm_gpusvm_pages_valid(struct drm_gpusvm *gpusvm,

+                           struct drm_gpusvm_pages *svm_pages);
+
  int drm_gpusvm_range_get_pages(struct drm_gpusvm *gpusvm,
                               struct drm_gpusvm_range *range,
                               const struct drm_gpusvm_ctx *ctx);
--
2.34.1

























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