[RFC 5/7] libxl: Handle Linux stubdomain specific QEMU options.

[Eric Shelton <eshelton@pobox.com>]

This patch creates an appropriate command line for the QEMU instance
running in a Linux-based stubdomain.

NOTE: a number of items are not currently implemented for Linux-based
stubdomains, such as:
- save/restore
- QMP socket
- graphics output (e.g., VNC)

Signed-off-by: Eric Shelton <eshelton@pobox.com>
---
 tools/libxl/libxl_dm.c | 86 ++++++++++++++++++++++++++++++++++----------------
 1 file changed, 58 insertions(+), 28 deletions(-)

diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index 8599a6a..68d5886 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -20,9 +20,12 @@
 #include "libxl_internal.h"
 #include <xen/hvm/e820.h>
 
-static const char *libxl_tapif_script(libxl__gc *gc)
+static const char *libxl_tapif_script(libxl__gc *gc,
+                                      const libxl_domain_build_info *info)
 {
 #if defined(__linux__) || defined(__FreeBSD__)
+    if (info->stubdomain_version == LIBXL_STUBDOMAIN_VERSION_LINUX)
+        return libxl__sprintf(gc, "/etc/qemu-ifup");
     return libxl__strdup(gc, "no");
 #else
     return libxl__sprintf(gc, "%s/qemu-ifup", libxl__xen_script_dir_path());
@@ -307,8 +310,8 @@ static char ** libxl__build_device_model_args_old(libxl__gc *gc,
                                       "tap,vlan=%d,ifname=%s,bridge=%s,"
                                       "script=%s,downscript=%s",
                                       nics[i].devid, ifname, nics[i].bridge,
-                                      libxl_tapif_script(gc),
-                                      libxl_tapif_script(gc)),
+                                      libxl_tapif_script(gc, b_info),
+                                      libxl_tapif_script(gc, b_info)),
                                   NULL);
                 ioemu_nics++;
             }
@@ -430,6 +433,7 @@ static char ** libxl__build_device_model_args_new(libxl__gc *gc,
     int i, connection, devid;
     uint64_t ram_size;
     const char *path, *chardev;
+    bool is_stubdom = libxl_defbool_val(b_info->device_model_stubdomain);
 
     dm_args = flexarray_make(gc, 16, 1);
 
@@ -437,15 +441,18 @@ static char ** libxl__build_device_model_args_new(libxl__gc *gc,
                       "-xen-domid",
                       libxl__sprintf(gc, "%d", guest_domid), NULL);
 
-    flexarray_append(dm_args, "-chardev");
-    flexarray_append(dm_args,
-                     libxl__sprintf(gc, "socket,id=libxl-cmd,"
-                                    "path=%s/qmp-libxl-%d,server,nowait",
-                                    libxl__run_dir_path(), guest_domid));
-
-    flexarray_append(dm_args, "-no-shutdown");
-    flexarray_append(dm_args, "-mon");
-    flexarray_append(dm_args, "chardev=libxl-cmd,mode=control");
+    /* There is currently no way to access the QMP socket in the stubdom */
+    if (!is_stubdom) {
+        flexarray_append(dm_args, "-chardev");
+        flexarray_append(dm_args,
+                         libxl__sprintf(gc, "socket,id=libxl-cmd,"
+                                        "path=%s/qmp-libxl-%d,server,nowait",
+                                        libxl__run_dir_path(), guest_domid));
+
+        flexarray_append(dm_args, "-no-shutdown");
+        flexarray_append(dm_args, "-mon");
+        flexarray_append(dm_args, "chardev=libxl-cmd,mode=control");
+    }
 
     for (i = 0; i < guest_config->num_channels; i++) {
         connection = guest_config->channels[i].connection;
@@ -483,7 +490,7 @@ static char ** libxl__build_device_model_args_new(libxl__gc *gc,
         flexarray_vappend(dm_args, "-name", c_info->name, NULL);
     }
 
-    if (vnc) {
+    if (vnc && !is_stubdom) {
         char *vncarg = NULL;
 
         flexarray_append(dm_args, "-vnc");
@@ -524,7 +531,7 @@ static char ** libxl__build_device_model_args_new(libxl__gc *gc,
         flexarray_append(dm_args, vncarg);
     }
 
-    if (sdl) {
+    if (sdl && !is_stubdom) {
         flexarray_append(dm_args, "-sdl");
         /* XXX sdl->{display,xauthority} into $DISPLAY/$XAUTHORITY */
     }
@@ -552,10 +559,19 @@ static char ** libxl__build_device_model_args_new(libxl__gc *gc,
                 return NULL;
             }
             if (b_info->u.hvm.serial) {
-                flexarray_vappend(dm_args,
-                                  "-serial", b_info->u.hvm.serial, NULL);
+                if (is_stubdom) {
+                    flexarray_vappend(dm_args,
+                                      "-serial", "/dev/hvc1", NULL);
+                } else {
+                    flexarray_vappend(dm_args,
+                                      "-serial", b_info->u.hvm.serial, NULL);
+                }
             } else if (b_info->u.hvm.serial_list) {
                 char **p;
+                if (is_stubdom) {
+                    flexarray_vappend(dm_args,
+                                      "-serial", "/dev/hvc1", NULL);
+                }
                 for (p = b_info->u.hvm.serial_list;
                      *p;
                      p++) {
@@ -570,7 +586,7 @@ static char ** libxl__build_device_model_args_new(libxl__gc *gc,
             flexarray_append(dm_args, "-nographic");
         }
 
-        if (libxl_defbool_val(b_info->u.hvm.spice.enable)) {
+        if (libxl_defbool_val(b_info->u.hvm.spice.enable) && !is_stubdom) {
             const libxl_spice_info *spice = &b_info->u.hvm.spice;
             char *spiceoptions = dm_spice_options(gc, spice);
             if (!spiceoptions)
@@ -700,8 +716,8 @@ static char ** libxl__build_device_model_args_new(libxl__gc *gc,
                                           "type=tap,id=net%d,ifname=%s,"
                                           "script=%s,downscript=%s",
                                           nics[i].devid, ifname,
-                                          libxl_tapif_script(gc),
-                                          libxl_tapif_script(gc)));
+                                          libxl_tapif_script(gc, b_info),
+                                          libxl_tapif_script(gc, b_info)));
                 ioemu_nics++;
             }
         }
@@ -789,6 +805,10 @@ static char ** libxl__build_device_model_args_new(libxl__gc *gc,
                     drive = libxl__sprintf
                         (gc, "if=ide,index=%d,media=cdrom,cache=writeback,id=ide-%i",
                          disk, dev_number);
+                else if (b_info->stubdomain_version == LIBXL_STUBDOMAIN_VERSION_LINUX)
+                    drive = libxl__sprintf
+                        (gc, "file=%s,if=ide,index=%d,media=cdrom,cache=writeback,format=%s,id=ide-%i",
+                         "/dev/xvdc", disk, "host_cdrom", dev_number);
                 else
                     drive = libxl__sprintf
                         (gc, "file=%s,if=ide,index=%d,media=cdrom,format=%s,cache=writeback,id=ide-%i",
@@ -824,10 +844,16 @@ static char ** libxl__build_device_model_args_new(libxl__gc *gc,
                     drive = libxl__sprintf
                         (gc, "file=%s,if=scsi,bus=0,unit=%d,format=%s,cache=writeback",
                          pdev_path, disk, format);
-                else if (disk < 4)
-                    drive = libxl__sprintf
-                        (gc, "file=%s,if=ide,index=%d,media=disk,format=%s,cache=writeback",
-                         pdev_path, disk, format);
+                else if (disk < 4) {
+                    if (b_info->stubdomain_version == LIBXL_STUBDOMAIN_VERSION_LINUX)
+                        drive = libxl__sprintf
+                                (gc, "file=%s,if=ide,index=%d,media=disk,cache=writeback,format=%s",
+                                 "/dev/xvda", disk, "host_device");
+                    else
+                        drive = libxl__sprintf
+                                (gc, "file=%s,if=ide,index=%d,media=disk,format=%s,cache=writeback",
+                                 pdev_path, disk, format);
+                }
                 else
                     continue; /* Do not emulate this disk */
             }
@@ -854,7 +880,7 @@ static char ** libxl__build_device_model_args(libxl__gc *gc,
                                         const libxl_domain_config *guest_config,
                                         const libxl__domain_build_state *state,
                                         int *dm_state_fd)
-/* dm_state_fd may be NULL iff caller knows we are using old stubdom
+/* dm_state_fd may be NULL iff caller knows we are using stubdom
  * and therefore will be passing a filename rather than a fd. */
 {
     libxl_ctx *ctx = libxl__gc_owner(gc);
@@ -865,8 +891,10 @@ static char ** libxl__build_device_model_args(libxl__gc *gc,
                                                   guest_domid, guest_config,
                                                   state);
     case LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN:
-        assert(dm_state_fd != NULL);
-        assert(*dm_state_fd < 0);
+        if (!libxl_defbool_val(guest_config->b_info.device_model_stubdomain)) {
+            assert(dm_state_fd != NULL);
+            assert(*dm_state_fd < 0);
+	}
         return libxl__build_device_model_args_new(gc, dm,
                                                   guest_domid, guest_config,
                                                   state, dm_state_fd);
@@ -922,7 +950,7 @@ static int libxl__vfb_and_vkb_from_hvm_guest_config(libxl__gc *gc,
 
 static int libxl__write_stub_dmargs(libxl__gc *gc,
                                     int dm_domid, int guest_domid,
-                                    char **args)
+                                    char **args, bool linux_stubdom)
 {
     libxl_ctx *ctx = libxl__gc_owner(gc);
     int i;
@@ -950,7 +978,9 @@ static int libxl__write_stub_dmargs(libxl__gc *gc,
     i = 1;
     dmargs[0] = '\0';
     while (args[i] != NULL) {
-        if (strcmp(args[i], "-sdl") && strcmp(args[i], "-M") && strcmp(args[i], "xenfv")) {
+        if (linux_stubdom ||
+            (strcmp(args[i], "-sdl") &&
+             strcmp(args[i], "-M") && strcmp(args[i], "xenfv"))) {
             strcat(dmargs, " ");
             strcat(dmargs, args[i]);
         }
-- 
1.8.5.5