libxl: add backend type and id to vkb

New field backend_type is added to vkb device in order to have QEMU and user
space backend simultaneously. Each vkb backend shall read appropriate XS entry
and service only own frontends. Id is a string field which used by the backend
to indentify the frontend.

Signed-off-by: Oleksandr Grytsov <oleksandr_grytsov@epam.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>

tools/libxl/libxl_create.c

@@ -1421,6 +1421,9 @@ static void domcreate_launch_dm(libxl__egc *egc, libxl__multidev *multidev,
         for (i = 0; i < d_config->num_vfbs; i++) {
             libxl__device_add(gc, domid, &libxl__vfb_devtype,
                               &d_config->vfbs[i]);
+        }
+
+        for (i = 0; i < d_config->num_vkbs; i++) {
             libxl__device_add(gc, domid, &libxl__vkb_devtype,
                               &d_config->vkbs[i]);
         }

tools/libxl/libxl_dm.c

@@ -1790,6 +1790,7 @@ static int libxl__vfb_and_vkb_from_hvm_guest_config(libxl__gc *gc,
 
     vkb->backend_domid = 0;
     vkb->devid = 0;
+
     return 0;
 }
 

tools/libxl/libxl_types.idl

@@ -247,6 +247,12 @@ libxl_vuart_type = Enumeration("vuart_type", [
     (1, "sbsa_uart"),
     ])
 
+libxl_vkb_backend = Enumeration("vkb_backend", [
+    (0, "UNKNOWN"),
+    (1, "QEMU"),
+    (2, "LINUX")
+    ])
+
 #
 # Complex libxl types
 #
@@ -626,6 +632,8 @@ libxl_device_vkb = Struct("device_vkb", [
     ("backend_domid", libxl_domid),
     ("backend_domname", string),
     ("devid", libxl_devid),
+    ("backend_type", libxl_vkb_backend),
+    ("unique_id", string)
     ])
 
 libxl_device_disk = Struct("device_disk", [

tools/libxl/libxl_vkb.c

@@ -14,12 +14,38 @@
 
 #include "libxl_internal.h"
 
+#include <xen/io/kbdif.h>
+
 static int libxl__device_vkb_setdefault(libxl__gc *gc, uint32_t domid,
                                         libxl_device_vkb *vkb, bool hotplug)
 {
+    if (vkb->backend_type == LIBXL_VKB_BACKEND_UNKNOWN) {
+        vkb->backend_type = LIBXL_VKB_BACKEND_QEMU;
+    }
+
     return libxl__resolve_domid(gc, vkb->backend_domname, &vkb->backend_domid);
 }
 
+static int libxl__device_vkb_dm_needed(libxl_device_vkb *vkb, uint32_t domid)
+{
+    return vkb->backend_type == LIBXL_VKB_BACKEND_QEMU;
+}
+
+static int libxl__set_xenstore_vkb(libxl__gc *gc, uint32_t domid,
+                                   libxl_device_vkb *vkb,
+                                   flexarray_t *back, flexarray_t *front,
+                                   flexarray_t *ro_front)
+{
+    flexarray_append_pair(back, "backend-type",
+                          (char *)libxl_vkb_backend_to_string(vkb->backend_type));
+
+    if (vkb->unique_id) {
+        flexarray_append_pair(back, XENKBD_FIELD_UNIQUE_ID, vkb->unique_id);
+    }
+
+    return 0;
+}
+
 int libxl_device_vkb_add(libxl_ctx *ctx, uint32_t domid, libxl_device_vkb *vkb,
                          const libxl_asyncop_how *ao_how)
 {
@@ -47,7 +73,10 @@ static LIBXL_DEFINE_UPDATE_DEVID(vkb)
 LIBXL_DEFINE_DEVICE_REMOVE(vkb)
 
 DEFINE_DEVICE_TYPE_STRUCT(vkb, VKBD,
-    .skip_attach = 1
+    .skip_attach = 1,
+    .dm_needed = (device_dm_needed_fn_t)libxl__device_vkb_dm_needed,
+    .set_xenstore_config = (device_set_xenstore_config_fn_t)
+                           libxl__set_xenstore_vkb
 );
 
 /*