libxl: Load guest BIOS from file

The path to the BIOS blob can be overriden by the xl's
bios_path_override option, or provided by u.hvm.bios_firmware in the
domain_build_info struct by other libxl user.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>

docs/man/xl.cfg.pod.5.in

@@ -1214,6 +1214,15 @@ Requires device_model_version=qemu-xen.
 
 =back
 
+=item B<bios_path_override="PATH">
+
+Override the path to the blob to be used as BIOS. The blob provided here MUST
+be consistent with the B<bios=> which you have specified. You should not
+normally need to specify this option.
+
+This options does not have any effect if using B<bios="rombios"> or
+B<device_model_version="qemu-xen-traditional">.
+
 =item B<pae=BOOLEAN>
 
 Hide or expose the IA32 Physical Address Extensions. These extensions

tools/libxl/libxl.h

@@ -949,6 +949,14 @@ void libxl_mac_copy(libxl_ctx *ctx, libxl_mac *dst, const libxl_mac *src);
  */
 #define LIBXL_HAVE_CHECKPOINTED_STREAM 1
 
+/*
+ * LIBXL_HAVE_BUILDINFO_HVM_SYSTEM_FIRMWARE
+ *
+ * libxl_domain_build_info has u.hvm.system_firmware field which can be use
+ * to provide a different firmware blob (like SeaBIOS or OVMF).
+ */
+#define LIBXL_HAVE_BUILDINFO_HVM_SYSTEM_FIRMWARE
+
 /*
  * ERROR_REMUS_XXX error code only exists from Xen 4.5, Xen 4.6 and it
  * is changed to ERROR_CHECKPOINT_XXX in Xen 4.7

tools/libxl/libxl_dom.c

@@ -862,6 +862,42 @@ err:
     return ret;
 }
 
+static int libxl__load_hvm_firmware_module(libxl__gc *gc,
+                                           const char *filename,
+                                           const char *what,
+                                           struct xc_hvm_firmware_module *m)
+{
+    int datalen = 0;
+    void *data = NULL;
+    int r, rc;
+
+    LOG(DEBUG, "Loading %s: %s", what, filename);
+    r = libxl_read_file_contents(CTX, filename, &data, &datalen);
+    if (r) {
+        /*
+         * Print a message only on ENOENT, other errors are logged by the
+         * function libxl_read_file_contents().
+         */
+        if (r == ENOENT)
+            LOGEV(ERROR, r, "failed to read %s file", what);
+        rc =  ERROR_FAIL;
+        goto out;
+    }
+    libxl__ptr_add(gc, data);
+    if (datalen) {
+        /* Only accept non-empty files */
+        m->data = data;
+        m->length = datalen;
+    } else {
+        LOG(ERROR, "file %s for %s is empty", filename, what);
+        rc = ERROR_INVAL;
+        goto out;
+    }
+    rc = 0;
+out:
+    return rc;
+}
+
 static int libxl__domain_firmware(libxl__gc *gc,
                                   libxl_domain_build_info *info,
                                   struct xc_dom_image *dom)
@@ -871,6 +907,7 @@ static int libxl__domain_firmware(libxl__gc *gc,
     int e, rc;
     int datalen = 0;
     void *data;
+    const char *bios_filename = NULL;
 
     if (info->u.hvm.firmware)
         firmware = info->u.hvm.firmware;
@@ -914,6 +951,30 @@ static int libxl__domain_firmware(libxl__gc *gc,
         goto out;
     }
 
+    if (info->device_model_version == LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN) {
+        if (info->u.hvm.system_firmware) {
+            bios_filename = info->u.hvm.system_firmware;
+        } else {
+            switch (info->u.hvm.bios) {
+            case LIBXL_BIOS_TYPE_SEABIOS:
+                bios_filename = libxl__seabios_path();
+                break;
+            case LIBXL_BIOS_TYPE_OVMF:
+                bios_filename = libxl__ovmf_path();
+                break;
+            case LIBXL_BIOS_TYPE_ROMBIOS:
+            default:
+                abort();
+            }
+        }
+    }
+
+    if (bios_filename) {
+        rc = libxl__load_hvm_firmware_module(gc, bios_filename, "BIOS",
+                                             &dom->system_firmware_module);
+        if (rc) goto out;
+    }
+
     if (info->u.hvm.smbios_firmware) {
         data = NULL;
         e = libxl_read_file_contents(ctx, info->u.hvm.smbios_firmware,

tools/libxl/libxl_internal.h

@@ -2318,6 +2318,8 @@ _hidden const char *libxl__xen_config_dir_path(void);
 _hidden const char *libxl__xen_script_dir_path(void);
 _hidden const char *libxl__lock_dir_path(void);
 _hidden const char *libxl__run_dir_path(void);
+_hidden const char *libxl__seabios_path(void);
+_hidden const char *libxl__ovmf_path(void);
 
 /*----- subprocess execution with timeout -----*/
 

tools/libxl/libxl_paths.c

@@ -35,6 +35,16 @@ const char *libxl__run_dir_path(void)
     return XEN_RUN_DIR;
 }
 
+const char *libxl__seabios_path(void)
+{
+    return SEABIOS_PATH;
+}
+
+const char *libxl__ovmf_path(void)
+{
+    return OVMF_PATH;
+}
+
 /*
  * Local variables:
  * mode: C

tools/libxl/libxl_types.idl

@@ -513,6 +513,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
                                        ("timer_mode",       libxl_timer_mode),
                                        ("nested_hvm",       libxl_defbool),
                                        ("altp2m",           libxl_defbool),
+                                       ("system_firmware",  string),
                                        ("smbios_firmware",  string),
                                        ("acpi_firmware",    string),
                                        ("hdtype",           libxl_hdtype),

tools/libxl/xl_cmdimpl.c

@@ -1565,12 +1565,17 @@ static void parse_config_data(const char *config_source,
 
         xlu_cfg_replace_string (config, "firmware_override",
                                 &b_info->u.hvm.firmware, 0);
-        if (!xlu_cfg_get_string(config, "bios", &buf, 0) &&
-            libxl_bios_type_from_string(buf, &b_info->u.hvm.bios)) {
+        xlu_cfg_replace_string (config, "bios_path_override",
+                                &b_info->u.hvm.system_firmware, 0);
+        if (!xlu_cfg_get_string(config, "bios", &buf, 0)) {
+            if (libxl_bios_type_from_string(buf, &b_info->u.hvm.bios)) {
                 fprintf(stderr, "ERROR: invalid value \"%s\" for \"bios\"\n",
                     buf);
                 exit (1);
-        }
+            }
+        } else if (b_info->u.hvm.system_firmware)
+            fprintf(stderr, "WARNING: "
+                    "bios_path_override given without specific bios name\n");
 
         xlu_cfg_get_defbool(config, "pae", &b_info->u.hvm.pae, 0);
         xlu_cfg_get_defbool(config, "apic", &b_info->u.hvm.apic, 0);