drm/i915: Use CPU mapping for userspace dma-buf mmap()

Userspace is the one in charge of flush CPU by wrapping mmap with
begin{,end}_cpu_access.

v2: Remove LLC check cause we have dma-buf sync providers now. Also, fix return
before transferring ownership when mmap fails.
v3: Fix return values.
v4: !obj->base.filp is user triggerable, so removed the WARN_ON.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Tiago Vignatti <tiago.vignatti@intel.com>
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1450820214-12509-6-git-send-email-tiago.vignatti@intel.com

diff --git a/drivers/gpu/drm/i915/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
index 8c9ed2a..1f3eef6 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_dmabuf.c
+++ b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
@@ -193,7 +193,23 @@ static void i915_gem_dmabuf_kunmap(struct dma_buf *dma_buf, unsigned long page_n
 
 static int i915_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma)
 {
-       return -EINVAL;
+       struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);
+       int ret;
+
+       if (obj->base.size < vma->vm_end - vma->vm_start)
+               return -EINVAL;
+
+       if (!obj->base.filp)
+               return -ENODEV;
+
+       ret = obj->base.filp->f_op->mmap(obj->base.filp, vma);
+       if (ret)
+               return ret;
+
+       fput(vma->vm_file);
+       vma->vm_file = get_file(obj->base.filp);
+
+       return 0;
 }
 
 static int i915_gem_begin_cpu_access(struct dma_buf *dma_buf, enum dma_data_direction direction)