[PATCH] Add device_model_pvdevice parameter for HVM guests

[Paul Durrant <paul.durrant@citrix.com>]

The parameter determines which, if any, xen-pvdevice is specified on the
QEMU command line. The default value is 'none' which means no argument will
be passed. A value of 'xenserver' specifies a xen-pvdevice with device-id
0xc000 (the initial value in the xenserver namespace - see
docs/misc/pci-device-reservations.txt).

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@citrix.com>
---
 docs/man/xl.cfg.pod.5       |   22 ++++++++++++++++++++++
 tools/libxl/libxl_dm.c      |    9 +++++++++
 tools/libxl/libxl_types.idl |    5 +++++
 tools/libxl/xl_cmdimpl.c    |   14 ++++++++++++++
 4 files changed, 50 insertions(+)

diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
index b7d64a6..2220bb6 100644
--- a/docs/man/xl.cfg.pod.5
+++ b/docs/man/xl.cfg.pod.5
@@ -1214,6 +1214,28 @@ you have selected.
 
 Assign an XSM security label to the device-model stubdomain.
 
+=item B<device_model_pvdevice="PVDEVICE">
+
+Selects which variant of the xen-pvdevice should be used for this
+guest. Valid values are:
+
+=over 4
+
+=item B<none>
+
+The xen-pvdevice should be omitted. This is the default.
+
+=item B<xenserver>
+
+The xenserver variant of the xen-pvdevice will be specified, enabling
+the use of XenServer PV drivers in the guest.
+
+=back
+
+This parameter only takes effect when device_model_version=qemu-xen.
+
+=back
+
 =item B<device_model_args=[ "ARG", "ARG", ...]>
 
 Pass additional arbitrary options on the device-model command
diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index ac1f90e..2924298 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -647,6 +647,15 @@ static char ** libxl__build_device_model_args_new(libxl__gc *gc,
             flexarray_append(dm_args, "-drive");
             flexarray_append(dm_args, drive);
         }
+
+        switch (b_info->u.hvm.device_model_pvdevice) {
+        case LIBXL_DEVICE_MODEL_PVDEVICE_XENSERVER:
+            flexarray_append(dm_args, "-device");
+            flexarray_append(dm_args, "xen-pvdevice,device-id=0xc000");
+            break;
+        default:
+            break;
+        }
     }
     flexarray_append(dm_args, NULL);
     return (char **) flexarray_contents(dm_args);
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index d218a2d..7165139 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -132,6 +132,10 @@ libxl_vga_interface_type = Enumeration("vga_interface_type", [
     (2, "STD"),
     ], init_val = 0)
 
+libxl_device_model_pvdevice = Enumeration("device_model_pvdevice", [
+    (0, "NONE"),
+    (1, "XENSERVER"),
+    ])
 #
 # Complex libxl types
 #
@@ -332,6 +336,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
                                        ("soundhw",          string),
                                        ("xen_platform_pci", libxl_defbool),
                                        ("usbdevice_list",   libxl_string_list),
+                                       ("device_model_pvdevice", libxl_device_model_pvdevice),
                                        ])),
                  ("pv", Struct(None, [("kernel", string),
                                       ("slack_memkb", MemKB),
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 8a478ba..cfaa54e 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -1526,6 +1526,20 @@ skip_vfb:
             exit (1);
 
         }
+
+        if (!xlu_cfg_get_string (config, "device_model_pvdevice", &buf, 0)) {
+            libxl_device_model_pvdevice d;
+
+            e = libxl_device_model_pvdevice_from_string(buf, &d);
+            if (e) {
+                fprintf(stderr,
+                        "xl: unknown device_model_pvdevice '%s'\n",
+                        buf);
+                exit(-ERROR_FAIL);
+            }
+                
+            b_info->u.hvm.device_model_pvdevice = d;
+        }
     }
 
     xlu_cfg_destroy(config);
-- 
1.7.10.4