From: Honglei Huang <[email protected]>

drm_gpusvm_pages is the layer that actually represents physical
pages/mappings it owns the dma_addr array, the dma_iova_state...
With the previous patch, so drm_gpusvm_pages is now strictly about
physical pages and their DMA view.

Since now the drm_gpusvm_pages instance is inherently bound to one
specific drm_device, make that ownership explicit by giving
drm_gpusvm_pages its own drm_device handle, and drive all DMA through
it instead of through the gpusvm:

  - Add drm to struct drm_gpusvm_pages and a matching drm parameter
    to drm_gpusvm_get_pages(); the dma device is bound on first use
    and immutable for the lifetime of the pages instance.
  - Route all DMA in drm_gpusvm_get_pages() / __drm_gpusvm_unmap_pages()
    through svm_pages->drm instead of gpusvm->drm.
  - Update existing callers (drm_gpusvm_range_get_pages, xe userptr)

Suggested-by: Matthew Brost <[email protected]>
Signed-off-by: Honglei Huang <[email protected]>
---
 drivers/gpu/drm/drm_gpusvm.c    | 37 ++++++++++++++++++++++++---------
 drivers/gpu/drm/xe/xe_userptr.c |  1 +
 include/drm/drm_gpusvm.h        |  3 +++
 3 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/drm_gpusvm.c b/drivers/gpu/drm/drm_gpusvm.c
index 6000d587cf2..3f076178b2a 100644
--- a/drivers/gpu/drm/drm_gpusvm.c
+++ b/drivers/gpu/drm/drm_gpusvm.c
@@ -1135,11 +1135,16 @@ static void __drm_gpusvm_unmap_pages(struct drm_gpusvm 
*gpusvm,
                                     unsigned long npages)
 {
        struct drm_pagemap *dpagemap = svm_pages->dpagemap;
-       struct device *dev = gpusvm->drm->dev;
+       struct device *dev;
        unsigned long i, j;
 
        lockdep_assert_held(&gpusvm->notifier_lock);
 
+       if (WARN_ON_ONCE(!svm_pages->drm))
+               return;
+
+       dev = svm_pages->drm->dev;
+
        if (svm_pages->flags.has_dma_mapping) {
                struct drm_gpusvm_pages_flags flags = {
                        .__flags = svm_pages->flags.__flags,
@@ -1379,6 +1384,7 @@ static bool drm_gpusvm_pages_valid_unlocked(struct 
drm_gpusvm *gpusvm,
  * drm_gpusvm_get_pages() - Get pages and populate GPU SVM pages struct
  * @gpusvm: Pointer to the GPU SVM structure
  * @svm_pages: The SVM pages to populate. This will contain the dma-addresses
+ * @drm: The DRM device that will own the DMA mappings. Stored into @svm_pages
  * @mm: The mm corresponding to the CPU range
  * @notifier: The corresponding notifier for the given CPU range
  * @pages_start: Start CPU address for the pages
@@ -1392,6 +1398,7 @@ static bool drm_gpusvm_pages_valid_unlocked(struct 
drm_gpusvm *gpusvm,
  */
 int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm,
                         struct drm_gpusvm_pages *svm_pages,
+                        struct drm_device *drm,
                         struct mm_struct *mm,
                         struct mmu_interval_notifier *notifier,
                         unsigned long pages_start, unsigned long pages_end,
@@ -1421,6 +1428,15 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm,
                                                           DMA_BIDIRECTIONAL;
        struct dma_iova_state *state = &svm_pages->state;
 
+       if (!drm)
+               return -EINVAL;
+       if (svm_pages->drm) {
+               if (svm_pages->drm != drm)
+                       return -EINVAL;
+       } else {
+               svm_pages->drm = drm;
+       }
+
 retry:
        if (time_after(jiffies, timeout))
                return -EBUSY;
@@ -1515,7 +1531,7 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm,
 
                                pagemap = page_pgmap(page);
                                dpagemap = drm_pagemap_page_to_dpagemap(page);
-                               if (drm_WARN_ON(gpusvm->drm, !dpagemap)) {
+                               if (drm_WARN_ON(drm, !dpagemap)) {
                                        /*
                                         * Raced. This is not supposed to happen
                                         * since hmm_range_fault() should've 
migrated
@@ -1527,10 +1543,10 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm,
                        }
                        svm_pages->dma_addr[j] =
                                dpagemap->ops->device_map(dpagemap,
-                                                         gpusvm->drm->dev,
+                                                         drm->dev,
                                                          page, order,
                                                          dma_dir);
-                       if (dma_mapping_error(gpusvm->drm->dev,
+                       if (dma_mapping_error(drm->dev,
                                              svm_pages->dma_addr[j].addr)) {
                                err = -EFAULT;
                                goto err_unmap;
@@ -1550,11 +1566,11 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm,
                        }
 
                        if (!i)
-                               dma_iova_try_alloc(gpusvm->drm->dev, state,
+                               dma_iova_try_alloc(drm->dev, state,
                                                   0, npages * PAGE_SIZE);
 
                        if (dma_use_iova(state)) {
-                               err = dma_iova_link(gpusvm->drm->dev, state,
+                               err = dma_iova_link(drm->dev, state,
                                                    hmm_pfn_to_phys(pfns[i]),
                                                    svm_pages->state_offset,
                                                    PAGE_SIZE << order,
@@ -1565,11 +1581,11 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm,
                                addr = state->addr + svm_pages->state_offset;
                                svm_pages->state_offset += PAGE_SIZE << order;
                        } else {
-                               addr = dma_map_page(gpusvm->drm->dev,
+                               addr = dma_map_page(drm->dev,
                                                    page, 0,
                                                    PAGE_SIZE << order,
                                                    dma_dir);
-                               if (dma_mapping_error(gpusvm->drm->dev, addr)) {
+                               if (dma_mapping_error(drm->dev, addr)) {
                                        err = -EFAULT;
                                        goto err_unmap;
                                }
@@ -1585,7 +1601,7 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm,
        }
 
        if (dma_use_iova(state)) {
-               err = dma_iova_sync(gpusvm->drm->dev, state, 0,
+               err = dma_iova_sync(drm->dev, state, 0,
                                    svm_pages->state_offset);
                if (err)
                        goto err_unmap;
@@ -1635,7 +1651,8 @@ int drm_gpusvm_range_get_pages(struct drm_gpusvm *gpusvm,
                               struct drm_gpusvm_range *range,
                               const struct drm_gpusvm_ctx *ctx)
 {
-       return drm_gpusvm_get_pages(gpusvm, &range->pages, gpusvm->mm,
+       return drm_gpusvm_get_pages(gpusvm, &range->pages, gpusvm->drm,
+                                   gpusvm->mm,
                                    &range->notifier->notifier,
                                    drm_gpusvm_range_start(range),
                                    drm_gpusvm_range_end(range), ctx);
diff --git a/drivers/gpu/drm/xe/xe_userptr.c b/drivers/gpu/drm/xe/xe_userptr.c
index 6761005c0b9..7e28f6868ff 100644
--- a/drivers/gpu/drm/xe/xe_userptr.c
+++ b/drivers/gpu/drm/xe/xe_userptr.c
@@ -75,6 +75,7 @@ int xe_vma_userptr_pin_pages(struct xe_userptr_vma *uvma)
                return 0;
 
        return drm_gpusvm_get_pages(&vm->svm.gpusvm, &uvma->userptr.pages,
+                                   &xe->drm,
                                    uvma->userptr.notifier.mm,
                                    &uvma->userptr.notifier,
                                    xe_vma_userptr(vma),
diff --git a/include/drm/drm_gpusvm.h b/include/drm/drm_gpusvm.h
index 3dba4b9516f..ed228d9ff6b 100644
--- a/include/drm/drm_gpusvm.h
+++ b/include/drm/drm_gpusvm.h
@@ -127,6 +127,7 @@ struct drm_gpusvm_pages_flags {
 /**
  * struct drm_gpusvm_pages - Structure representing a GPU SVM mapped pages
  *
+ * @drm: The DRM device that owns the dma mappings
  * @dma_addr: Device address array
  * @dpagemap: The struct drm_pagemap of the device pages we're dma-mapping.
  *            Note this is assuming only one drm_pagemap per range is allowed.
@@ -136,6 +137,7 @@ struct drm_gpusvm_pages_flags {
  * @flags: Flags for the range; see &struct drm_gpusvm_pages_flags
  */
 struct drm_gpusvm_pages {
+       struct drm_device *drm;
        struct drm_pagemap_addr *dma_addr;
        struct drm_pagemap *dpagemap;
        struct dma_iova_state state;
@@ -328,6 +330,7 @@ void drm_gpusvm_range_set_unmapped(struct drm_gpusvm_range 
*range,
 
 int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm,
                         struct drm_gpusvm_pages *svm_pages,
+                        struct drm_device *drm,
                         struct mm_struct *mm,
                         struct mmu_interval_notifier *notifier,
                         unsigned long pages_start, unsigned long pages_end,
-- 
2.34.1

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