[PATCH] drm/i915/gem: Support discontiguous lmem object maps

[Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>]

Create a vmap for discontinguous lmem objects to support
i915_gem_object_pin_map().

Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Matthew Auld <matthew.auld@xxxxxxxxx>
---
 drivers/gpu/drm/i915/gem/i915_gem_pages.c | 45 ++++++++++++++++++++---
 1 file changed, 39 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_pages.c b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
index 75197ca696a8..edc3febbb71d 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_pages.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
@@ -158,10 +158,10 @@ static void __i915_gem_object_reset_page_iter(struct drm_i915_gem_object *obj)
 
 static void unmap_object(struct drm_i915_gem_object *obj, void *ptr)
 {
-	if (i915_gem_object_is_lmem(obj))
-		io_mapping_unmap((void __force __iomem *)ptr);
-	else if (is_vmalloc_addr(ptr))
+	if (is_vmalloc_addr(ptr))
 		vunmap(ptr);
+	else if (i915_gem_object_is_lmem(obj))
+		io_mapping_unmap((void __force __iomem *)ptr);
 	else
 		kunmap(kmap_to_page(ptr));
 }
@@ -236,6 +236,12 @@ int __i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
 	return err;
 }
 
+static inline pte_t io_wc_pte(dma_addr_t addr)
+{
+	return pte_mkspecial(pfn_pte(addr >> PAGE_SHIFT,
+				     pgprot_writecombine(PAGE_KERNEL)));
+}
+
 /* The 'mapping' part of i915_gem_object_pin_map() below */
 static void *i915_gem_object_map(struct drm_i915_gem_object *obj,
 				 enum i915_map_type type)
@@ -251,13 +257,40 @@ static void *i915_gem_object_map(struct drm_i915_gem_object *obj,
 	void *addr;
 
 	if (i915_gem_object_is_lmem(obj)) {
-		void __iomem *io;
+		struct vm_struct *area;
+		dma_addr_t addr;
+		pte_t **ptes;
+		void *mem;
 
 		if (type != I915_MAP_WC)
 			return NULL;
 
-		io = i915_gem_object_lmem_io_map(obj, 0, obj->base.size);
-		return (void __force *)io;
+		if (i915_gem_object_is_contiguous(obj)) {
+			void __iomem *io =
+				i915_gem_object_lmem_io_map(obj,
+							    0, obj->base.size);
+
+			return (void __force *)io;
+		}
+
+		mem = kvmalloc_array(obj->base.size >> PAGE_SHIFT,
+				     sizeof(*ptes),
+				     GFP_KERNEL);
+		if (!mem)
+			return NULL;
+
+		area = alloc_vm_area(obj->base.size, mem);
+		if (!area) {
+			kvfree(mem);
+			return NULL;
+		}
+
+		ptes = mem;
+		for_each_sgt_daddr(addr, sgt_iter, sgt)
+			**ptes++ = io_wc_pte(addr);
+		kvfree(mem);
+
+		return area->addr;
 	}
 
 	/* A single page can always be kmapped */
-- 
2.25.0.rc0

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