Commit a599b986 authored by Thomas Hellström's avatar Thomas Hellström
Browse files

drm/pagemap, drm/xe: Add refcounting to struct drm_pagemap 



With the end goal of being able to free unused pagemaps
and allocate them on demand, add a refcount to struct drm_pagemap,
remove the xe embedded drm_pagemap, allocating and freeing it
explicitly.

v2:
- Make the drm_pagemap pointer in drm_gpusvm_pages reference-counted.
v3:
- Call drm_pagemap_get() before drm_pagemap_put() in drm_gpusvm_pages
  (Himal Prasad Ghimiray)

Signed-off-by: default avatarThomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com> #v1
Reviewed-by: default avatarHimal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Acked-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> # For merging through drm-xe.
Link: https://patch.msgid.link/20251219113320.183860-5-thomas.hellstrom@linux.intel.com
parent 16b5ad31

drivers/gpu/drm/drm_gpusvm.c

+3 −0
Original line number Diff line number Diff line
@@ -1038,6 +1038,7 @@ static void __drm_gpusvm_unmap_pages(struct drm_gpusvm *gpusvm, 
		flags.has_dma_mapping = false;

		WRITE_ONCE(svm_pages->flags.__flags, flags.__flags);



		drm_pagemap_put(svm_pages->dpagemap);

		svm_pages->dpagemap = NULL;

	}

}
@@ -1434,6 +1435,8 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm, 


	if (pagemap) {

		flags.has_devmem_pages = true;

		drm_pagemap_get(dpagemap);

		drm_pagemap_put(svm_pages->dpagemap);

		svm_pages->dpagemap = dpagemap;

	}

drivers/gpu/drm/drm_pagemap.c

+51 −0
Original line number Diff line number Diff line
@@ -543,6 +543,57 @@ static int drm_pagemap_migrate_populate_ram_pfn(struct vm_area_struct *vas, 
	return -ENOMEM;

}



static void drm_pagemap_release(struct kref *ref)

{

	struct drm_pagemap *dpagemap = container_of(ref, typeof(*dpagemap), ref);



	kfree(dpagemap);

}



/**

 * drm_pagemap_create() - Create a struct drm_pagemap.

 * @dev: Pointer to a struct device providing the device-private memory.

 * @pagemap: Pointer to a pre-setup struct dev_pagemap providing the struct pages.

 * @ops: Pointer to the struct drm_pagemap_ops.

 *

 * Allocate and initialize a struct drm_pagemap.

 *

 * Return: A refcounted pointer to a struct drm_pagemap on success.

 * Error pointer on error.

 */

struct drm_pagemap *

drm_pagemap_create(struct device *dev,

		   struct dev_pagemap *pagemap,

		   const struct drm_pagemap_ops *ops)

{

	struct drm_pagemap *dpagemap = kzalloc(sizeof(*dpagemap), GFP_KERNEL);



	if (!dpagemap)

		return ERR_PTR(-ENOMEM);



	kref_init(&dpagemap->ref);

	dpagemap->dev = dev;

	dpagemap->ops = ops;

	dpagemap->pagemap = pagemap;



	return dpagemap;

}

EXPORT_SYMBOL(drm_pagemap_create);



/**

 * drm_pagemap_put() - Put a struct drm_pagemap reference

 * @dpagemap: Pointer to a struct drm_pagemap object.

 *

 * Puts a struct drm_pagemap reference and frees the drm_pagemap object

 * if the refount reaches zero.

 */

void drm_pagemap_put(struct drm_pagemap *dpagemap)

{

	if (likely(dpagemap))

		kref_put(&dpagemap->ref, drm_pagemap_release);

}

EXPORT_SYMBOL(drm_pagemap_put);



/**

 * drm_pagemap_evict_to_ram() - Evict GPU SVM range to RAM

 * @devmem_allocation: Pointer to the device memory allocation

drivers/gpu/drm/xe/xe_svm.c

+18 −8
Original line number Diff line number Diff line
@@ -868,7 +868,7 @@ static int xe_drm_pagemap_populate_mm(struct drm_pagemap *dpagemap, 
				      struct mm_struct *mm,

				      unsigned long timeslice_ms)

{

	struct xe_vram_region *vr = container_of(dpagemap, typeof(*vr), dpagemap);

	struct xe_vram_region *vr = container_of(dpagemap->pagemap, typeof(*vr), pagemap);

	struct dma_fence *pre_migrate_fence = NULL;

	struct xe_device *xe = vr->xe;

	struct device *dev = xe->drm.dev;
@@ -1392,7 +1392,7 @@ u8 xe_svm_ranges_zap_ptes_in_range(struct xe_vm *vm, u64 start, u64 end) 


static struct drm_pagemap *tile_local_pagemap(struct xe_tile *tile)

{

	return &tile->mem.vram->dpagemap;

	return tile->mem.vram->dpagemap;

}



/**
@@ -1502,6 +1502,15 @@ int xe_devm_add(struct xe_tile *tile, struct xe_vram_region *vr) 
		return ret;

	}



	vr->dpagemap = drm_pagemap_create(dev, &vr->pagemap,

					  &xe_drm_pagemap_ops);

	if (IS_ERR(vr->dpagemap)) {

		drm_err(&xe->drm, "Failed to create drm_pagemap tile %d memory: %pe\n",

			tile->id, vr->dpagemap);

		ret = PTR_ERR(vr->dpagemap);

		goto out_no_dpagemap;

	}



	vr->pagemap.type = MEMORY_DEVICE_PRIVATE;

	vr->pagemap.range.start = res->start;

	vr->pagemap.range.end = res->end;
@@ -1509,22 +1518,23 @@ int xe_devm_add(struct xe_tile *tile, struct xe_vram_region *vr) 
	vr->pagemap.ops = drm_pagemap_pagemap_ops_get();

	vr->pagemap.owner = xe_svm_devm_owner(xe);

	addr = devm_memremap_pages(dev, &vr->pagemap);



	vr->dpagemap.dev = dev;

	vr->dpagemap.ops = &xe_drm_pagemap_ops;



	if (IS_ERR(addr)) {

		devm_release_mem_region(dev, res->start, resource_size(res));

		ret = PTR_ERR(addr);

		drm_err(&xe->drm, "Failed to remap tile %d memory, errno %pe\n",

			tile->id, ERR_PTR(ret));

		return ret;

		goto out_failed_memremap;

	}

	vr->hpa_base = res->start;



	drm_dbg(&xe->drm, "Added tile %d memory [%llx-%llx] to devm, remapped to %pr\n",

		tile->id, vr->io_start, vr->io_start + vr->usable_size, res);

	return 0;



out_failed_memremap:

	drm_pagemap_put(vr->dpagemap);

out_no_dpagemap:

	devm_release_mem_region(dev, res->start, resource_size(res));

	return ret;

}

#else

int xe_svm_alloc_vram(struct xe_tile *tile,

drivers/gpu/drm/xe/xe_vram_types.h

+1 −1
Original line number Diff line number Diff line
@@ -72,7 +72,7 @@ struct xe_vram_region { 
	 * @dpagemap: The struct drm_pagemap of the ZONE_DEVICE memory

	 * pages of this tile.

	 */

	struct drm_pagemap dpagemap;

	struct drm_pagemap *dpagemap;

	/**

	 * @hpa_base: base host physical address

	 *

include/drm/drm_pagemap.h

+36 −0
Original line number Diff line number Diff line
@@ -130,11 +130,15 @@ struct drm_pagemap_ops { 
 * struct drm_pagemap: Additional information for a struct dev_pagemap

 * used for device p2p handshaking.

 * @ops: The struct drm_pagemap_ops.

 * @ref: Reference count.

 * @dev: The struct drevice owning the device-private memory.

 * @pagemap: Pointer to the underlying dev_pagemap.

 */

struct drm_pagemap {

	const struct drm_pagemap_ops *ops;

	struct kref ref;

	struct device *dev;

	struct dev_pagemap *pagemap;

};



struct drm_pagemap_devmem;
@@ -209,6 +213,37 @@ struct drm_pagemap_devmem_ops { 
			   struct dma_fence *pre_migrate_fence);

};



struct drm_pagemap *drm_pagemap_create(struct device *dev,

				       struct dev_pagemap *pagemap,

				       const struct drm_pagemap_ops *ops);



#if IS_ENABLED(CONFIG_DRM_GPUSVM)



void drm_pagemap_put(struct drm_pagemap *dpagemap);



#else



static inline void drm_pagemap_put(struct drm_pagemap *dpagemap)

{

}



#endif /* IS_ENABLED(CONFIG_DRM_GPUSVM) */



/**

 * drm_pagemap_get() - Obtain a reference on a struct drm_pagemap

 * @dpagemap: Pointer to the struct drm_pagemap.

 *

 * Return: Pointer to the struct drm_pagemap.

 */

static inline struct drm_pagemap *

drm_pagemap_get(struct drm_pagemap *dpagemap)

{

	if (likely(dpagemap))

		kref_get(&dpagemap->ref);



	return dpagemap;

}



/**

 * struct drm_pagemap_devmem - Structure representing a GPU SVM device memory allocation

 *
@@ -257,3 +292,4 @@ int drm_pagemap_populate_mm(struct drm_pagemap *dpagemap, 
			    unsigned long timeslice_ms);



#endif