[Qemu-devel] [RFC PATCH V3 1/2] xen: pass kernel initrd to qemu

[Chunyan Liu <cyliu@suse.com>]

xen side patch to support xen HVM direct kernel boot:
support 'kernel', 'ramdisk', 'cmdline' (and 'root', 'extra' as well
which would be deprecated later) in HVM config file, parse config file,
pass -kernel, -initrd, -append parameters to qemu.

It's working with qemu-xen when using the default BIOS (seabios).

[config example]
kernel="/mnt/vmlinuz-3.0.13-0.27-default"
ramdisk="/mnt/initrd-3.0.13-0.27-default"
cmdline="/dev/hda2 console=tty0 console=ttyS0"
or:
kernel="/mnt/vmlinuz-3.0.13-0.27-default"
ramdisk="/mnt/initrd-3.0.13-0.27-default"
root="/dev/hda2"
extra="console=tty0 console=ttyS0"

Signed-off-by: Chunyan Liu <cyliu@suse.com>
---
 docs/man/xl.cfg.pod.5       | 57 +++++++++++++++++++++++++--------------
 tools/libxl/libxl.h         | 13 +++++++++
 tools/libxl/libxl_dm.c      | 15 +++++++++++
 tools/libxl/libxl_types.idl |  3 +++
 tools/libxl/xl_cmdimpl.c    | 66 ++++++++++++++++++++++++++++++---------------
 5 files changed, 112 insertions(+), 42 deletions(-)

diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
index a94d037..c460dd4 100644
--- a/docs/man/xl.cfg.pod.5
+++ b/docs/man/xl.cfg.pod.5
@@ -304,6 +304,41 @@ Action to take if the domain crashes.  Default is C<destroy>.
 
 =back
 
+=head3 Direct Kernel Boot
+
+Currently, direct kernel boot can be supported by PV guests, and HVM guests
+with limitations. For HVM guests, in case of stubdom-dm and old rombios,
+direct kernel boot is not supported.
+
+=over 4
+
+=item B<kernel="PATHNAME">
+
+Load the specified file as the kernel image.
+
+=item B<ramdisk="PATHNAME">
+
+Load the specified file as the ramdisk.
+
+=item B<cmdline="STRING">
+
+Append B<cmdline="STRING"> to the kernel command line. (Note: it is
+guest specific what meaning this has). It will replace
+B<root="STRING"> plus B<extra="STRING">. When B<cmdline="STRING"> is
+set, B<root="STRING"> and B<extra="STRING"> will be ignored.
+
+=item B<root="STRING">
+
+Append B<root="STRING"> to the kernel command line (Note: it is guest
+specific what meaning this has). It will be deprecated.
+
+=item B<extra="STRING">
+
+Append B<STRING> to the kernel command line. (Note: it is guest
+specific what meaning this has). It will be deprecated.
+
+=back
+
 =head3 Other Options
 
 =over 4
@@ -646,20 +681,12 @@ The following options apply only to Paravirtual guests.
 
 =over 4
 
-=item B<kernel="PATHNAME">
-
-Load the specified file as the kernel image.  Either B<kernel> or
-B<bootloader> must be specified for PV guests.
-
-=item B<ramdisk="PATHNAME">
-
-Load the specified file as the ramdisk.
-
 =item B<bootloader="PROGRAM">
 
 Run C<PROGRAM> to find the kernel image and ramdisk to use.  Normally
 C<PROGRAM> would be C<pygrub>, which is an emulation of
-grub/grub2/syslinux.
+grub/grub2/syslinux. Either B<kernel> or B<bootloader> must be specified
+for PV guests.
 
 =item B<bootloader_args=[ "ARG", "ARG", ...]>
 
@@ -667,16 +694,6 @@ Append B<ARG>s to the arguments to the B<bootloader>
 program. Alternatively if the argument is a simple string then it will
 be split into words at whitespace (this second option is deprecated).
 
-=item B<root="STRING">
-
-Append B<root="STRING"> to the kernel command line (Note: it is guest
-specific what meaning this has).
-
-=item B<extra="STRING">
-
-Append B<STRING> to the kernel command line. Note: it is guest
-specific what meaning this has).
-
 =item B<e820_host=BOOLEAN>
 
 Selects whether to expose the host e820 (memory map) to the guest via
diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index 80947c3..0ef393e 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -482,6 +482,19 @@
  */
 #define LIBXL_HAVE_DEVICE_PCI_SEIZE 1
 
+/*
+ * LIBXL_HAVE_BUILDINFO_HVM_DIRECT_KERNEL_BOOT
+ *
+ * If this is defined, then the libxl_domain_build_info structure will
+ * contain hvm.kernel, hvm.cmdline and hvm.ramdisk. hvm.kernel is a string
+ * to indicate kernel image location, hvm.ramdisk is a string to indicate
+ * ramdisk location, hvm.cmdline is a string to indicate the paramters which
+ * would be appened to kernel image.
+ *
+ * If it is set, guest will be booted from the indicated kernel and ramdisk.
+ */
+#define LIBXL_HAVE_BUILDINFO_HVM_DIRECT_KERNEL_BOOT 1
+
 /* Functions annotated with LIBXL_EXTERNAL_CALLERS_ONLY may not be
  * called from within libxl itself. Callers outside libxl, who
  * do not #include libxl_internal.h, are fine. */
diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index 51ab2bf..fe53441 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -196,6 +196,12 @@ static char ** libxl__build_device_model_args_old(libxl__gc *gc,
         int nr_set_cpus = 0;
         char *s;
 
+        if (b_info->u.hvm.kernel) {
+            LOG(ERROR, "direct kernel boot is not supported by "
+                "qemu-xen-traditional");
+            return NULL;
+        }
+
         if (b_info->u.hvm.serial) {
             flexarray_vappend(dm_args, "-serial", b_info->u.hvm.serial, NULL);
         }
@@ -479,6 +485,15 @@ static char ** libxl__build_device_model_args_new(libxl__gc *gc,
     if (b_info->type == LIBXL_DOMAIN_TYPE_HVM) {
         int ioemu_nics = 0;
 
+        if (b_info->u.hvm.kernel)
+            flexarray_vappend(dm_args, "-kernel", b_info->u.hvm.kernel, NULL);
+
+        if (b_info->u.hvm.ramdisk)
+            flexarray_vappend(dm_args, "-initrd", b_info->u.hvm.ramdisk, NULL);
+
+        if (b_info->u.hvm.cmdline)
+            flexarray_vappend(dm_args, "-append", b_info->u.hvm.cmdline, NULL);
+
         if (b_info->u.hvm.serial) {
             flexarray_vappend(dm_args, "-serial", b_info->u.hvm.serial, NULL);
         }
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 52f1aa9..a96b228 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -336,6 +336,9 @@ libxl_domain_build_info = Struct("domain_build_info",[
     ("event_channels",   uint32),
     ("u", KeyedUnion(None, libxl_domain_type, "type",
                 [("hvm", Struct(None, [("firmware",         string),
+                                       ("kernel",           string),
+                                       ("cmdline",          string),
+                                       ("ramdisk",          string),
                                        ("bios",             libxl_bios_type),
                                        ("pae",              libxl_defbool),
                                        ("apic",             libxl_defbool),
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 5195914..a31e8c6 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -725,6 +725,37 @@ static void parse_top_level_sdl_options(XLU_Config *config,
     xlu_cfg_replace_string (config, "xauthority", &sdl->xauthority, 0);
 }
 
+static char *parse_cmdline(XLU_Config *config)
+{
+    char *cmdline = NULL;
+    const char *root = NULL, *extra = NULL, *buf = NULL;
+
+    xlu_cfg_get_string (config, "cmdline", &buf, 0);
+    xlu_cfg_get_string (config, "root", &root, 0);
+    xlu_cfg_get_string (config, "extra", &extra, 0);
+
+    if (buf) {
+        cmdline = strdup(buf);
+        if (root || extra)
+            fprintf(stderr, "Warning: ignoring deprecated root= and extra= "
+                    "in favour of cmdline=\n");
+    } else {
+        if (root) {
+            if (asprintf(&cmdline, "root=%s %s", root, extra) == -1)
+                cmdline = NULL;
+        } else if (extra) {
+            cmdline = strdup(extra);
+        }
+    }
+
+    if ((buf || root || extra) && !cmdline) {
+        fprintf(stderr, "Failed to allocate memory for cmdline\n");
+        exit(1);
+    }
+
+    return cmdline;
+}
+
 static void parse_config_data(const char *config_source,
                               const char *config_data,
                               int config_len,
@@ -1007,9 +1038,18 @@ static void parse_config_data(const char *config_source,
 
     switch(b_info->type) {
     case LIBXL_DOMAIN_TYPE_HVM:
-        if (!xlu_cfg_get_string (config, "kernel", &buf, 0))
-            fprintf(stderr, "WARNING: ignoring \"kernel\" directive for HVM guest. "
-                    "Use \"firmware_override\" instead if you really want a non-default firmware\n");
+        if (!xlu_cfg_get_string (config, "kernel", &buf, 0)) {
+            if (!strcmp(libxl_basename(buf), "hvmloader"))
+                fprintf(stderr, "WARNING: you seem to be using \"kernel\" "
+                        "directive to override HVM guest firmware. Ignore "
+                        "that. Use \"firmware_override\" instead if you "
+                        "really want a non-default firmware\n");
+            else
+                b_info->u.hvm.kernel = strdup(buf);
+        }
+
+        b_info->u.hvm.cmdline = parse_cmdline(config);
+        xlu_cfg_replace_string (config, "ramdisk", &b_info->u.hvm.ramdisk, 0);
 
         xlu_cfg_replace_string (config, "firmware_override",
                                 &b_info->u.hvm.firmware, 0);
@@ -1061,26 +1101,8 @@ static void parse_config_data(const char *config_source,
         break;
     case LIBXL_DOMAIN_TYPE_PV:
     {
-        char *cmdline = NULL;
-        const char *root = NULL, *extra = "";
-
         xlu_cfg_replace_string (config, "kernel", &b_info->u.pv.kernel, 0);
 
-        xlu_cfg_get_string (config, "root", &root, 0);
-        xlu_cfg_get_string (config, "extra", &extra, 0);
-
-        if (root) {
-            if (asprintf(&cmdline, "root=%s %s", root, extra) == -1)
-                cmdline = NULL;
-        } else {
-            cmdline = strdup(extra);
-        }
-
-        if ((root || extra) && !cmdline) {
-            fprintf(stderr, "Failed to allocate memory for cmdline\n");
-            exit(1);
-        }
-
         xlu_cfg_replace_string (config, "bootloader", &b_info->u.pv.bootloader, 0);
         switch (xlu_cfg_get_list_as_string_list(config, "bootloader_args",
                                       &b_info->u.pv.bootloader_args, 1))
@@ -1108,7 +1130,7 @@ static void parse_config_data(const char *config_source,
             exit(1);
         }
 
-        b_info->u.pv.cmdline = cmdline;
+        b_info->u.pv.cmdline = parse_cmdline(config);
         xlu_cfg_replace_string (config, "ramdisk", &b_info->u.pv.ramdisk, 0);
         break;
     }
-- 
1.8.4.5