drm/shmem-helper: Switch to vmf_insert_pfn

We want to stop gup, which isn't the case if we use vmf_insert_page
and VM_MIXEDMAP, because that does not set pte_special.

v2: With this shmem gem helpers now definitely need CONFIG_MMU (0day)

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>

drivers/gpu/drm/Kconfig

@@ -207,7 +207,7 @@ config DRM_KMS_CMA_HELPER
 
 config DRM_GEM_SHMEM_HELPER
 	bool
-	depends on DRM
+	depends on DRM && MMU
 	help
 	  Choose this if you need the GEM shmem helper functions
 

drivers/gpu/drm/drm_gem_shmem_helper.c

@@ -543,7 +543,7 @@ static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf)
 	} else {
 		page = shmem->pages[page_offset];
 
-		ret = vmf_insert_page(vma, vmf->address, page);
+		ret = vmf_insert_pfn(vma, vmf->address, page_to_pfn(page));
 	}
 
 	mutex_unlock(&shmem->pages_lock);
@@ -613,7 +613,7 @@ int drm_gem_shmem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
 		return ret;
 	}
 
-	vma->vm_flags |= VM_MIXEDMAP | VM_DONTEXPAND;
+	vma->vm_flags |= VM_PFNMAP | VM_DONTEXPAND;
 	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 	if (shmem->map_wc)
 		vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);