[PATCH v3] Add vendor_device 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>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Ian Jackson <ian.jackson@citrix.com>
---
v3:
 - Changed names from using 'pvdevice' to 'vendor_device'
 - Dropped 'device_model' prefix in xl.cfg parameter
 - Adhere to general format of LIBXL_HAVE_ definitions

v2:
 - Added LIBXL_HAVE_PVDEVICE to libxl.h
 - Added more text to xl.cfg manpage to call out the device-id of
   the xenserver pvdevice and point readers at
   docs/misc/pci-device-reservations.txt

 docs/man/xl.cfg.pod.5       |   23 +++++++++++++++++++++++
 tools/libxl/libxl.h         |    8 ++++++++
 tools/libxl/libxl_dm.c      |    9 +++++++++
 tools/libxl/libxl_types.idl |    5 +++++
 tools/libxl/xl_cmdimpl.c    |   14 ++++++++++++++
 5 files changed, 59 insertions(+)

diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
index 069b73f..08d6cc4 100644
--- a/docs/man/xl.cfg.pod.5
+++ b/docs/man/xl.cfg.pod.5
@@ -1176,6 +1176,29 @@ documentation.
 
 =back
 
+=item B<vendor_device="VENDOR_DEVICE">
+
+Selects which variant of the QEMU 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 (device-id=C000) 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.
+See F<docs/misc/pci-device-reservations.txt> for more information.
+
+=back
+
 =head2 Device-Model Options
 
 The following options control the selection of the device-model.  This
diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index 37e4d82..b9af2b1 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -82,6 +82,14 @@
 #define LIBXL_HAVE_DOMAIN_NODEAFFINITY 1
 
 /*
+ * LIBXL_HAVE_BUILD_INFO_HVM_VENDOR_DEVICE indicates that the
+ * libxl_vendor_device field is present in the hvm sections of
+ * libxl_domain_build_info. This field tells libxl which
+ * flavour of xen-pvdevice to enable in QEMU.
+ */
+#define LIBXL_HAVE_BUILD_INFO_HVM_VENDOR_DEVICE 1
+
+/*
  * libxl ABI compatibility
  *
  * The only guarantee which libxl makes regarding ABI compatibility
diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index 7e54c02..615dcf3 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.vendor_device) {
+        case LIBXL_VENDOR_DEVICE_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..85341a0 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_vendor_device = Enumeration("vendor_device", [
+    (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),
+                                       ("vendor_device",    libxl_vendor_device),
                                        ])),
                  ("pv", Struct(None, [("kernel", string),
                                       ("slack_memkb", MemKB),
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 5bef969..b583942 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -1532,6 +1532,20 @@ skip_vfb:
             exit (1);
 
         }
+
+        if (!xlu_cfg_get_string (config, "vendor_device", &buf, 0)) {
+            libxl_vendor_device d;
+
+            e = libxl_vendor_device_from_string(buf, &d);
+            if (e) {
+                fprintf(stderr,
+                        "xl: unknown vendor_device '%s'\n",
+                        buf);
+                exit(-ERROR_FAIL);
+            }
+                
+            b_info->u.hvm.vendor_device = d;
+        }
     }
 
     xlu_cfg_destroy(config);
-- 
1.7.10.4