i915: use io_mapping_map_user

Replace the home-grown remap_io_mapping that abuses apply_to_page_range
with the proper io_mapping_map_user interface.

Link: https://lkml.kernel.org/r/20210326055505.1424432-4-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/gpu/drm/i915/Kconfig

@@ -20,6 +20,7 @@ config DRM_I915
 	select INPUT if ACPI
 	select ACPI_VIDEO if ACPI
 	select ACPI_BUTTON if ACPI
+	select IO_MAPPING
 	select SYNC_FILE
 	select IOSF_MBI
 	select CRC32

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

@@ -367,11 +367,10 @@ static vm_fault_t vm_fault_gtt(struct vm_fault *vmf)
 		goto err_unpin;
 
 	/* Finally, remap it using the new GTT offset */
-	ret = remap_io_mapping(area,
-			       area->vm_start + (vma->ggtt_view.partial.offset << PAGE_SHIFT),
-			       (ggtt->gmadr.start + vma->node.start) >> PAGE_SHIFT,
-			       min_t(u64, vma->size, area->vm_end - area->vm_start),
-			       &ggtt->iomap);
+	ret = io_mapping_map_user(&ggtt->iomap, area, area->vm_start +
+			(vma->ggtt_view.partial.offset << PAGE_SHIFT),
+			(ggtt->gmadr.start + vma->node.start) >> PAGE_SHIFT,
+			min_t(u64, vma->size, area->vm_end - area->vm_start));
 	if (ret)
 		goto err_fence;
 

drivers/gpu/drm/i915/i915_drv.h

@@ -1905,9 +1905,6 @@ int i915_reg_read_ioctl(struct drm_device *dev, void *data,
 			struct drm_file *file);
 
 /* i915_mm.c */
-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(struct vm_area_struct *vma,
 		unsigned long addr, unsigned long size,
 		struct scatterlist *sgl, resource_size_t iobase);

drivers/gpu/drm/i915/i915_mm.c

@@ -37,17 +37,6 @@ struct remap_pfn {
 	resource_size_t iobase;
 };
 
-static int remap_pfn(pte_t *pte, unsigned long addr, void *data)
-{
-	struct remap_pfn *r = data;
-
-	/* Special PTE are not associated with any struct page */
-	set_pte_at(r->mm, addr, pte, pte_mkspecial(pfn_pte(r->pfn, r->prot)));
-	r->pfn++;
-
-	return 0;
-}
-
 #define use_dma(io) ((io) != -1)
 
 static inline unsigned long sgt_pfn(const struct remap_pfn *r)
@@ -77,40 +66,7 @@ static int remap_sg(pte_t *pte, unsigned long addr, void *data)
 	return 0;
 }
 
-/**
- * remap_io_mapping - remap an IO mapping to userspace
- * @vma: user vma to map to
- * @addr: target user address to start at
- * @pfn: physical address of kernel memory
- * @size: size of map area
- * @iomap: the source io_mapping
- *
- *  Note: this is only safe if the mm semaphore is held when called.
- */
-int remap_io_mapping(struct vm_area_struct *vma,
-		     unsigned long addr, unsigned long pfn, unsigned long size,
-		     struct io_mapping *iomap)
-{
-	struct remap_pfn r;
-	int err;
-
 #define EXPECTED_FLAGS (VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP)
-	GEM_BUG_ON((vma->vm_flags & EXPECTED_FLAGS) != EXPECTED_FLAGS);
-
-	/* We rely on prevalidation of the io-mapping to skip track_pfn(). */
-	r.mm = vma->vm_mm;
-	r.pfn = pfn;
-	r.prot = __pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
-			  (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK));
-
-	err = apply_to_page_range(r.mm, addr, size, remap_pfn, &r);
-	if (unlikely(err)) {
-		zap_vma_ptes(vma, addr, (r.pfn - pfn) << PAGE_SHIFT);
-		return err;
-	}
-
-	return 0;
-}
 
 /**
  * remap_io_sg - remap an IO mapping to userspace