vfio: add edid api for display (vgpu) devices.

This allows to set EDID monitor information for the vgpu display, for a
more flexible display configuration, using a special vfio region.  Check
the comment describing struct vfio_region_gfx_edid for more details.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

include/uapi/linux/vfio.h

@@ -301,6 +301,56 @@ struct vfio_region_info_cap_type {
 #define VFIO_REGION_SUBTYPE_INTEL_IGD_HOST_CFG	(2)
 #define VFIO_REGION_SUBTYPE_INTEL_IGD_LPC_CFG	(3)
 
+#define VFIO_REGION_TYPE_GFX                    (1)
+#define VFIO_REGION_SUBTYPE_GFX_EDID            (1)
+
+/**
+ * struct vfio_region_gfx_edid - EDID region layout.
+ *
+ * Set display link state and EDID blob.
+ *
+ * The EDID blob has monitor information such as brand, name, serial
+ * number, physical size, supported video modes and more.
+ *
+ * This special region allows userspace (typically qemu) set a virtual
+ * EDID for the virtual monitor, which allows a flexible display
+ * configuration.
+ *
+ * For the edid blob spec look here:
+ *    https://en.wikipedia.org/wiki/Extended_Display_Identification_Data
+ *
+ * On linux systems you can find the EDID blob in sysfs:
+ *    /sys/class/drm/${card}/${connector}/edid
+ *
+ * You can use the edid-decode ulility (comes with xorg-x11-utils) to
+ * decode the EDID blob.
+ *
+ * @edid_offset: location of the edid blob, relative to the
+ *               start of the region (readonly).
+ * @edid_max_size: max size of the edid blob (readonly).
+ * @edid_size: actual edid size (read/write).
+ * @link_state: display link state (read/write).
+ * VFIO_DEVICE_GFX_LINK_STATE_UP: Monitor is turned on.
+ * VFIO_DEVICE_GFX_LINK_STATE_DOWN: Monitor is turned off.
+ * @max_xres: max display width (0 == no limitation, readonly).
+ * @max_yres: max display height (0 == no limitation, readonly).
+ *
+ * EDID update protocol:
+ *   (1) set link-state to down.
+ *   (2) update edid blob and size.
+ *   (3) set link-state to up.
+ */
+struct vfio_region_gfx_edid {
+	__u32 edid_offset;
+	__u32 edid_max_size;
+	__u32 edid_size;
+	__u32 max_xres;
+	__u32 max_yres;
+	__u32 link_state;
+#define VFIO_DEVICE_GFX_LINK_STATE_UP    1
+#define VFIO_DEVICE_GFX_LINK_STATE_DOWN  2
+};
+
 /*
  * The MSIX mappable capability informs that MSIX data of a BAR can be mmapped
  * which allows direct access to non-MSIX registers which happened to be within