BACKPORT: FROMGIT: virtio: fix build for configs without dma-bufs

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: David Stevens <stevensd@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20200819031011.310180-1-stevensd@chromium.org
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
(cherry picked from commit 9fe2f89
 git://anongit.freedesktop.org/drm/drm-misc drm-misc-next)

Conflicts: trivial rebase conflicts in with virtwl build config

BUG=b:142423916
TEST=builds

Change-Id: If6f93dcdd52db5d02142ad13d872909d3d782d80
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/2405752
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Commit-Queue: Guenter Roeck <groeck@chromium.org>
Tested-by: Guenter Roeck <groeck@chromium.org>

drivers/gpu/drm/virtio/Kconfig

@@ -5,6 +5,7 @@ config DRM_VIRTIO_GPU
 	depends on PCI
 	select DRM_KMS_HELPER
 	select DRM_TTM
+	select VIRTIO_DMA_SHARED_BUFFER
 	help
 	   This is the virtual GPU driver for virtio.  It can be used with
 	   QEMU based VMMs (like KVM or Xen).

drivers/virtio/Kconfig

@@ -95,6 +95,13 @@ config VIRTIO_MMIO_CMDLINE_DEVICES
 
 	 If unsure, say 'N'.
 
+config VIRTIO_DMA_SHARED_BUFFER
+	tristate
+	depends on DMA_SHARED_BUFFER
+	help
+	 This option adds a flavor of dma buffers that are backed by
+	 virtio resources.
+
 config VIRTIO_WL
 	bool "Virtio Wayland driver"
 	depends on VIRTIO

drivers/virtio/Makefile

@@ -1,9 +1,10 @@
 # SPDX-License-Identifier: GPL-2.0
-obj-$(CONFIG_VIRTIO) += virtio.o virtio_ring.o virtio_dma_buf.o
+obj-$(CONFIG_VIRTIO) += virtio.o virtio_ring.o
 obj-$(CONFIG_VIRTIO_MMIO) += virtio_mmio.o
 obj-$(CONFIG_VIRTIO_PCI) += virtio_pci.o
 virtio_pci-y := virtio_pci_modern.o virtio_pci_common.o
 virtio_pci-$(CONFIG_VIRTIO_PCI_LEGACY) += virtio_pci_legacy.o
 obj-$(CONFIG_VIRTIO_BALLOON) += virtio_balloon.o
 obj-$(CONFIG_VIRTIO_INPUT) += virtio_input.o
 obj-$(CONFIG_VIRTIO_WL) += virtio_wl.o
+obj-$(CONFIG_VIRTIO_DMA_SHARED_BUFFER) += virtio_dma_buf.o

drivers/virtio/virtio_dma_buf.c

@@ -5,6 +5,7 @@
  * Copyright (C) 2020 Google, Inc.
  */
 
+#include <linux/module.h>
 #include <linux/virtio_dma_buf.h>
 
 /**
@@ -83,3 +84,5 @@ int virtio_dma_buf_get_uuid(struct dma_buf *dma_buf,
 	return ops->get_uuid(dma_buf, uuid);
 }
 EXPORT_SYMBOL(virtio_dma_buf_get_uuid);
+
+MODULE_LICENSE("GPL");