[PATCH] Revert "i915: use io_mapping_map_user"

[Matthew Auld]

This reverts commit b739f125e4ebd73d10ed30a856574e13649119ed.
---
 drivers/gpu/drm/i915/Kconfig             |  1 -
 drivers/gpu/drm/i915/gem/i915_gem_mman.c |  9 ++---
 drivers/gpu/drm/i915/i915_drv.h          |  3 ++
 drivers/gpu/drm/i915/i915_mm.c           | 44 ++++++++++++++++++++++++
 4 files changed, 52 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/Kconfig b/drivers/gpu/drm/i915/Kconfig
index 93f4d059fc89..1e1cb245fca7 100644
--- a/drivers/gpu/drm/i915/Kconfig
+++ b/drivers/gpu/drm/i915/Kconfig
@@ -20,7 +20,6 @@ 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
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
index f6fe5cb01438..8598a1c78a4c 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
@@ -367,10 +367,11 @@ static vm_fault_t vm_fault_gtt(struct vm_fault *vmf)
 		goto err_unpin;
 
 	/* Finally, remap it using the new GTT offset */
-	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));
+	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);
 	if (ret)
 		goto err_fence;
 
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 0f6d27da69ac..e926f20c5b82 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1941,6 +1941,9 @@ 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);
diff --git a/drivers/gpu/drm/i915/i915_mm.c b/drivers/gpu/drm/i915/i915_mm.c
index 9a777b0ff59b..666808cb3a32 100644
--- a/drivers/gpu/drm/i915/i915_mm.c
+++ b/drivers/gpu/drm/i915/i915_mm.c
@@ -37,6 +37,17 @@ 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)
@@ -66,7 +77,40 @@ 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
-- 
2.26.3