[PATCH v8 2/5] drm/gpusvm: embed struct drm_device into drm_gpusvm_pages

[Honglei Huang <honghuan@amd.com>]

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 route all DMA in
    drm_gpusvm_get_pages() / __drm_gpusvm_unmap_pages() through
    svm_pages->drm instead of gpusvm->drm.
  - Bind svm_pages->drm where the pages object is initialised
    (drm_gpusvm_range_alloc() and the xe userptr setup) and require
    it to be set on entry to drm_gpusvm_get_pages(); the dma device
    is immutable for the lifetime of the pages instance. A later
    patch introduces drm_gpusvm_init_pages() to centralise this.

Suggested-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Honglei Huang <honghuan@amd.com>
---
 drivers/gpu/drm/drm_gpusvm.c    | 30 ++++++++++++++++++++----------
 drivers/gpu/drm/xe/xe_userptr.c |  2 ++
 include/drm/drm_gpusvm.h        |  2 ++
 3 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/drm_gpusvm.c b/drivers/gpu/drm/drm_gpusvm.c
index abdfdaaf5e2..604554e40f6 100644
--- a/drivers/gpu/drm/drm_gpusvm.c
+++ b/drivers/gpu/drm/drm_gpusvm.c
@@ -641,6 +641,7 @@ drm_gpusvm_range_alloc(struct drm_gpusvm *gpusvm,
 	range->itree.last = ALIGN(fault_addr + 1, chunk_size) - 1;
 	INIT_LIST_HEAD(&range->entry);
 	range->pages.notifier_seq = LONG_MAX;
+	range->pages.drm = gpusvm->drm;
 	range->flags.migrate_devmem = migrate_devmem ? 1 : 0;
 
 	return range;
@@ -1135,11 +1136,16 @@ 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 (!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,
@@ -1421,6 +1427,9 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm,
 							   DMA_BIDIRECTIONAL;
 	struct dma_iova_state *state = &svm_pages->state;
 
+	if (!svm_pages->drm)
+		return -EINVAL;
+
 retry:
 	if (time_after(jiffies, timeout))
 		return -EBUSY;
@@ -1520,7 +1529,7 @@ 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(svm_pages->drm, !dpagemap)) {
 					/*
 					 * Raced. This is not supposed to happen
 					 * since hmm_range_fault() should've migrated
@@ -1532,10 +1541,10 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm,
 			}
 			svm_pages->dma_addr[j] =
 				dpagemap->ops->device_map(dpagemap,
-							  gpusvm->drm->dev,
+							  svm_pages->drm->dev,
 							  page, order,
 							  dma_dir);
-			if (dma_mapping_error(gpusvm->drm->dev,
+			if (dma_mapping_error(svm_pages->drm->dev,
 					      svm_pages->dma_addr[j].addr)) {
 				err = -EFAULT;
 				goto err_unmap;
@@ -1555,11 +1564,11 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm,
 			}
 
 			if (!i)
-				dma_iova_try_alloc(gpusvm->drm->dev, state,
+				dma_iova_try_alloc(svm_pages->drm->dev, state,
 						   0, npages * PAGE_SIZE);
 
 			if (dma_use_iova(state)) {
-				err = dma_iova_link(gpusvm->drm->dev, state,
+				err = dma_iova_link(svm_pages->drm->dev, state,
 						    hmm_pfn_to_phys(pfns[i]),
 						    svm_pages->state_offset,
 						    PAGE_SIZE << order,
@@ -1570,11 +1579,11 @@ 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(svm_pages->drm->dev,
 						    page, 0,
 						    PAGE_SIZE << order,
 						    dma_dir);
-				if (dma_mapping_error(gpusvm->drm->dev, addr)) {
+				if (dma_mapping_error(svm_pages->drm->dev, addr)) {
 					err = -EFAULT;
 					goto err_unmap;
 				}
@@ -1590,7 +1599,7 @@ 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(svm_pages->drm->dev, state, 0,
 				    svm_pages->state_offset);
 		if (err)
 			goto err_unmap;
@@ -1640,7 +1649,8 @@ 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->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..1b540e62af6 100644
--- a/drivers/gpu/drm/xe/xe_userptr.c
+++ b/drivers/gpu/drm/xe/xe_userptr.c
@@ -390,6 +390,7 @@ int xe_userptr_setup(struct xe_userptr_vma *uvma, unsigned long start,
 		     unsigned long range)
 {
 	struct xe_userptr *userptr = &uvma->userptr;
+	struct xe_vm *vm = xe_vma_vm(&uvma->vma);
 	int err;
 
 	INIT_LIST_HEAD(&userptr->invalidate_link);
@@ -402,6 +403,7 @@ int xe_userptr_setup(struct xe_userptr_vma *uvma, unsigned long start,
 		return err;
 
 	userptr->pages.notifier_seq = LONG_MAX;
+	userptr->pages.drm = &vm->xe->drm;
 
 	return 0;
 }
diff --git a/include/drm/drm_gpusvm.h b/include/drm/drm_gpusvm.h
index 251a7266a73..842353afb27 100644
--- a/include/drm/drm_gpusvm.h
+++ b/include/drm/drm_gpusvm.h
@@ -129,6 +129,7 @@ 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.
@@ -138,6 +139,7 @@ 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;
-- 
2.34.1