[PATCH 1/2] libxl: adding support to use -machine option of QEMU.

[Anthony PERARD <anthony.perard@citrix.com>]

It adds a new config option, "qemu_machine_override".

This can be used in the future to switch to a Q35 based device model. It
can also be used on a recent QEMU to avoid adding the xen-platform
device used to setup PV drivers in the guest.

Two possible values for now are "pc" or "xenfv" but there are
equivalents and xenfv is the default.  A possible future use could be
qemu_machine_override="q35" when this machine will be able to start
successfully on Xen.

When passed to qemu, libxl automatically adds ",accel=xen" to the
machine option.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
---
 tools/libxl/libxl_dm.c      | 7 +++++--
 tools/libxl/libxl_types.idl | 1 +
 tools/libxl/xl_cmdimpl.c    | 3 +++
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index 292e351..3d4a913 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -608,7 +608,7 @@ static char ** libxl__build_device_model_args_new(libxl__gc *gc,
     }
     for (i = 0; b_info->extra && b_info->extra[i] != NULL; i++)
         flexarray_append(dm_args, b_info->extra[i]);
-    flexarray_append(dm_args, "-M");
+    flexarray_append(dm_args, "-machine");
     switch (b_info->type) {
     case LIBXL_DOMAIN_TYPE_PV:
         flexarray_append(dm_args, "xenpv");
@@ -616,7 +616,10 @@ static char ** libxl__build_device_model_args_new(libxl__gc *gc,
             flexarray_append(dm_args, b_info->extra_pv[i]);
         break;
     case LIBXL_DOMAIN_TYPE_HVM:
-        flexarray_append(dm_args, "xenfv");
+        if (b_info->qemu_machine)
+            flexarray_append(dm_args, GCSPRINTF("%s,accel=xen", b_info->qemu_machine));
+        else
+            flexarray_append(dm_args, "xenfv");
         for (i = 0; b_info->extra_hvm && b_info->extra_hvm[i] != NULL; i++)
             flexarray_append(dm_args, b_info->extra_hvm[i]);
         break;
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index cba8eff..4141501 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -317,6 +317,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
     # if you set device_model you must set device_model_version too
     ("device_model",     string),
     ("device_model_ssidref", uint32),
+    ("qemu_machine",     string),
 
     # extra parameters pass directly to qemu, NULL terminated
     ("extra",            libxl_string_list),
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 341863e..4de6858 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -1491,6 +1491,9 @@ skip_vfb:
     }
 
 
+    xlu_cfg_replace_string (config, "qemu_machine_override",
+                            &b_info->qemu_machine, 0);
+
     xlu_cfg_replace_string (config, "device_model_override",
                             &b_info->device_model, 0);
     if (!xlu_cfg_get_string (config, "device_model_version", &buf, 0)) {
-- 
Anthony PERARD