drm/i915: Introduce remap_io_sg() to prefault discontiguous objects (1764b992) · Commits · 戴 / test

drivers/gpu/drm/i915/gem/i915_gem_mman.c

+12 −20

Original line number	Diff line number	Diff line
		@@ -236,42 +236,34 @@ static vm_fault_t vm_fault_cpu(struct vm_fault *vmf)
		struct vm_area_struct *area = vmf->vma;
		struct i915_mmap_offset *mmo = area->vm_private_data;
		struct drm_i915_gem_object *obj = mmo->obj;
		unsigned long i, size = area->vm_end - area->vm_start;
		bool write = area->vm_flags & VM_WRITE;
		vm_fault_t ret = VM_FAULT_SIGBUS;
		int err;

		if (!i915_gem_object_has_struct_page(obj))
		return ret;
		if (unlikely(!i915_gem_object_has_struct_page(obj)))
		return VM_FAULT_SIGBUS;

		/* Sanity check that we allow writing into this object */
		if (i915_gem_object_is_readonly(obj) && write)
		return ret;
		if (unlikely(i915_gem_object_is_readonly(obj) &&
		area->vm_flags & VM_WRITE))
		return VM_FAULT_SIGBUS;

		err = i915_gem_object_pin_pages(obj);
		if (err)
		return i915_error_to_vmf_fault(err);
		goto out;

		/* PTEs are revoked in obj->ops->put_pages() */
		for (i = 0; i < size >> PAGE_SHIFT; i++) {
		struct page *page = i915_gem_object_get_page(obj, i);
		err = remap_io_sg_page(area,
		area->vm_start, area->vm_end - area->vm_start,
		obj->mm.pages->sgl);

		ret = vmf_insert_pfn(area,
		(unsigned long)area->vm_start + i * PAGE_SIZE,
		page_to_pfn(page));
		if (ret != VM_FAULT_NOPAGE)
		break;
		}

		if (write) {
		if (area->vm_flags & VM_WRITE) {
		GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj));
		obj->cache_dirty = true; /* XXX flush after PAT update? */
		obj->mm.dirty = true;
		}

		i915_gem_object_unpin_pages(obj);

		return ret;
		out:
		return i915_error_to_vmf_fault(err);
		}

		static vm_fault_t vm_fault_gtt(struct vm_fault *vmf)

drivers/gpu/drm/i915/i915_drv.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -2015,6 +2015,9 @@ int i915_reg_read_ioctl(struct drm_device dev, void data,
		int remap_io_mapping(struct vm_area_struct *vma,
		unsigned long addr, unsigned long pfn, unsigned long size,
		struct io_mapping *iomap);
		int remap_io_sg_page(struct vm_area_struct *vma,
		unsigned long addr, unsigned long size,
		struct scatterlist *sgl);

		static inline int intel_hws_csb_write_index(struct drm_i915_private *i915)
		{

drivers/gpu/drm/i915/i915_mm.c

+59 −0

Original line number	Diff line number	Diff line
		@@ -33,6 +33,8 @@ struct remap_pfn {
		struct mm_struct *mm;
		unsigned long pfn;
		pgprot_t prot;

		struct sgt_iter sgt;
		};

		static int remap_pfn(pte_t pte, unsigned long addr, void data)
		@@ -46,6 +48,30 @@ static int remap_pfn(pte_t pte, unsigned long addr, void data)
		return 0;
		}

		static inline unsigned long sgt_pfn(const struct sgt_iter *sgt)
		{
		return sgt->pfn + (sgt->curr >> PAGE_SHIFT);
		}

		static int remap_sg_page(pte_t pte, unsigned long addr, void data)
		{
		struct remap_pfn *r = data;

		if (GEM_WARN_ON(!r->sgt.pfn))
		return -EINVAL;

		/* Special PTE are not associated with any struct page */
		set_pte_at(r->mm, addr, pte,
		pte_mkspecial(pfn_pte(sgt_pfn(&r->sgt), r->prot)));
		r->pfn++; /* track insertions in case we need to unwind later */

		r->sgt.curr += PAGE_SIZE;
		if (r->sgt.curr >= r->sgt.max)
		r->sgt = __sgt_iter(__sg_next(r->sgt.sgp), false);

		return 0;
		}

		/**
		* remap_io_mapping - remap an IO mapping to userspace
		* @vma: user vma to map to
		@@ -80,3 +106,36 @@ int remap_io_mapping(struct vm_area_struct *vma,

		return 0;
		}

		/**
		* remap_io_sg_page - remap an IO mapping to userspace
		* @vma: user vma to map to
		* @addr: target user address to start at
		* @size: size of map area
		* @sgl: Start sg entry
		*
		* Note: this is only safe if the mm semaphore is held when called.
		*/
		int remap_io_sg_page(struct vm_area_struct *vma,
		unsigned long addr, unsigned long size,
		struct scatterlist *sgl)
		{
		struct remap_pfn r = {
		.mm = vma->vm_mm,
		.prot = vma->vm_page_prot,
		.sgt = __sgt_iter(sgl, false),
		};
		int err;

		/* We rely on prevalidation of the io-mapping to skip track_pfn(). */
		GEM_BUG_ON((vma->vm_flags & EXPECTED_FLAGS) != EXPECTED_FLAGS);

		flush_cache_range(vma, addr, size);
		err = apply_to_page_range(r.mm, addr, size, remap_sg_page, &r);
		if (unlikely(err)) {
		zap_vma_ptes(vma, addr, r.pfn << PAGE_SHIFT);
		return err;
		}

		return 0;
		}

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