bootloader: Reject module2 without multiboot2

GRUB2 will fail if module2 is used without a previous call to
multiboot2 so raise an exception instead of pretending that it is
actually a hypervisor.

Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>

Author: rosslagerwall

tests/data/grub-no-multiboot.cfg

@@ -0,0 +1,10 @@
+serial --unit=0 --speed=115200
+terminal_input serial console
+terminal_output serial console
+set default=0
+set timeout=5
+menuentry 'XCP-ng' {
+	search --label --set root root-vgdorj
+	module2 /boot/vmlinuz-4.19-xen root=LABEL=root-vgdorj ro nolvm hpet=disable console=hvc0 console=tty0 quiet vga=785 splash plymouth.ignore-serial-consoles
+	module2 /boot/initrd-4.19-xen.img
+}

tests/test_bootloader.py

@@ -25,6 +25,11 @@ def test_grub2(self):
         proc.stdout.close()
         proc.wait()
 
+    def test_no_multiboot(self):
+        # A module2 line without a multiboot2 line is an error
+        with self.assertRaises(RuntimeError):
+            Bootloader.readGrub2("tests/data/grub-no-multiboot.cfg")
+
 class TestLinuxBootloader(unittest.TestCase):
     def setUp(self):
         self.tmpdir = mkdtemp(prefix="testbl")

xcp/bootloader.py

@@ -195,8 +195,8 @@ def parse_boot_entry(line):
                         hypervisor, hypervisor_args = parse_boot_entry(l)
                     elif l.startswith("module2"):
                         if not hypervisor:
-                            hypervisor, hypervisor_args = parse_boot_entry(l)
-                        elif kernel:
+                            raise RuntimeError("Need a multiboot2 kernel")
+                        if kernel:
                             initrd = l.split(None, 1)[1]
                         else:
                             kernel, kernel_args = parse_boot_entry(l)