[PATCH v2 08/12] libxl: Q35 support (new option device_model_machine)

[Joel Upham <jupham125@xxxxxxxxx>]

Provide a new domain config option to select the emulated machine type,
device_model_machine. It has following possible values:
- "i440" - i440 emulation (default)
- "q35" - emulate a Q35 machine. By default, the storage interface is AHCI.

Note that omitting device_model_machine parameter means i440 system
by default, so the default behavior doesn't change for existing domain
config files.

Setting device_model_machine to "q35" sends '-machine q35,accel=xen'
argument to QEMU. Unlike i440, there no separate machine type
to enable/disable Xen platform device, it is controlled via a machine
property only. See 'libxl: Xen Platform device support for Q35' patch for
a detailed description.

Signed-off-by: Alexey Gerasimenko <x1917x@xxxxxxxxx>
Signed-off-by: Joel Upham <jupham125@xxxxxxxxx>
---
 tools/libs/light/libxl_dm.c      | 20 ++++++++++++++------
 tools/libs/light/libxl_types.idl |  8 ++++++++
 tools/xl/xl_parse.c              | 14 ++++++++++++++
 3 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/tools/libs/light/libxl_dm.c b/tools/libs/light/libxl_dm.c
index fc264a3a13..17bc2113e1 100644
--- a/tools/libs/light/libxl_dm.c
+++ b/tools/libs/light/libxl_dm.c
@@ -1809,13 +1809,21 @@ static int libxl__build_device_model_args_new(libxl__gc 
*gc,
             flexarray_append(dm_args, b_info->extra_pv[i]);
         break;
     case LIBXL_DOMAIN_TYPE_HVM:
-        if (!libxl_defbool_val(b_info->u.hvm.xen_platform_pci)) {
-            /* Switching here to the machine "pc" which does not add
-             * the xen-platform device instead of the default "xenfv" machine.
-             */
-            machinearg = libxl__strdup(gc, "pc,accel=xen,suppress-vmdesc=on");
+        if (b_info->device_model_machine == LIBXL_DEVICE_MODEL_MACHINE_Q35) {
+            if (!libxl_defbool_val(b_info->u.hvm.xen_platform_pci)) {
+                machinearg = libxl__sprintf(gc, "q35,accel=xen");
+            } else {
+                machinearg = libxl__sprintf(gc, 
"q35,accel=xen,xen-platform-dev=on");
+            }
         } else {
-            machinearg = libxl__strdup(gc, "xenfv,suppress-vmdesc=on");
+            if (!libxl_defbool_val(b_info->u.hvm.xen_platform_pci)) {
+                /* Switching here to the machine "pc" which does not add
+                 * the xen-platform device instead of the default "xenfv" 
machine.
+                 */
+                machinearg = libxl__strdup(gc, 
"pc,accel=xen,suppress-vmdesc=on");
+            } else {
+                machinearg = libxl__strdup(gc, "xenfv,suppress-vmdesc=on");
+            }
         }
         if (b_info->u.hvm.mmio_hole_memkb) {
             uint64_t max_ram_below_4g = (1ULL << 32) -
diff --git a/tools/libs/light/libxl_types.idl b/tools/libs/light/libxl_types.idl
index c10292e0d7..b1aadae877 100644
--- a/tools/libs/light/libxl_types.idl
+++ b/tools/libs/light/libxl_types.idl
@@ -108,6 +108,13 @@ libxl_device_model_version = 
Enumeration("device_model_version", [
     (2, "QEMU_XEN"),             # Upstream based qemu-xen device model
     ])
 
+libxl_device_model_machine = Enumeration("device_model_machine", [
+    (0, "UNKNOWN"),
+    (1, "I440"),
+    (2, "Q35"),
+    ])
+
+
 libxl_console_type = Enumeration("console_type", [
     (0, "UNKNOWN"),
     (1, "SERIAL"),
@@ -575,6 +582,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
     ("device_model_ssidref", uint32),
     ("device_model_ssid_label", string),
     ("device_model_user", string),
+    ("device_model_machine", libxl_device_model_machine),
 
     # extra parameters pass directly to qemu, NULL terminated
     ("extra",            libxl_string_list),
diff --git a/tools/xl/xl_parse.c b/tools/xl/xl_parse.c
index 1f6f47daf4..e6fb7a409a 100644
--- a/tools/xl/xl_parse.c
+++ b/tools/xl/xl_parse.c
@@ -2689,6 +2689,20 @@ skip_usbdev:
     if (!xlu_cfg_get_long (config, "stubdomain_memory", &l, 0))
         b_info->stubdomain_memkb = l * 1024;
 
+    if (!xlu_cfg_get_string (config, "device_model_machine", &buf, 0)) {
+        if (!strcmp(buf, "i440")) {
+            b_info->device_model_machine = LIBXL_DEVICE_MODEL_MACHINE_I440;
+        } else if (!strcmp(buf, "q35")) {
+            b_info->device_model_machine = LIBXL_DEVICE_MODEL_MACHINE_Q35;
+        } else {
+            fprintf(stderr,
+                    "Unknown device_model_machine \"%s\" specified\n", buf);
+            exit(1);
+        }
+    } else {
+        b_info->device_model_machine = LIBXL_DEVICE_MODEL_MACHINE_UNKNOWN;
+    }
+
 #define parse_extra_args(type)                                            \
     e = xlu_cfg_get_list_as_string_list(config, "device_model_args"#type, \
                                     &b_info->extra##type, 0);            \
-- 
2.34.1