[virt-tools-list] [virt-install PATCH 3/7] virtinst: cli: Provide a default value for the 'policy' argument

[Erik Skultety]

Policy is a 4-byte bitfield used to turn on/off certain behaviour within
the SEV firmware. For a detailed table of supported flags, see
https://libvirt.org/formatdomain.html#launchSecurity.
Most of the flags are related to advanced features (some of them don't
even exist at the moment), except for the first 2 bits which determine
whether debug mode should be turned on and whether the same key should
be used to encrypt memory of multiple guests respectively.

>From security POV, most users will probably want separate keys for
individual guests, thus the value 0x03 was selected as the policy
default.

Signed-off-by: Erik Skultety <eskultet at redhat.com>
---
 tests/clitest.py |  1 +
 virtinst/cli.py  | 25 ++++++++++++++++++++++++-
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/tests/clitest.py b/tests/clitest.py
index c0efabf7..3958871e 100644
--- a/tests/clitest.py
+++ b/tests/clitest.py
@@ -877,6 +877,7 @@ c.add_invalid("--disk none --location nfs:example.com/fake --nonetworks")  # Usi
 
 c = vinst.add_category("kvm-x86_64-launch-security", "--disk none --noautoconsole")
 c.add_compare("--boot uefi --machine q35 --launch-security type=sev,reduced_phys_bits=1,policy=0x0001,cbitpos=47,dh_cert=BASE64CERT,session=BASE64SESSION --connect " + utils.URIs.kvm_amd_q35, "x86_64-launch-security-sev-full")  # Full cmdline
+c.add_valid("--boot uefi --machine q35 --launch-security sev,reduced_phys_bits=1,cbitpos=47 --connect " + utils.URIs.kvm_amd_q35)  # Default policy == 0x0003 will be used
 c.add_invalid("--launch-security policy=0x0001 --connect " + utils.URIs.kvm_amd_q35)  # Missing launch-security 'type'
 
 c = vinst.add_category("kvm-q35", "--noautoconsole --connect " + utils.URIs.kvm_q35)
diff --git a/virtinst/cli.py b/virtinst/cli.py
index 0a76b074..4621b3ae 100644
--- a/virtinst/cli.py
+++ b/virtinst/cli.py
@@ -3847,13 +3847,27 @@ class ParserLaunchSecurity(VirtCLIParser):
     guest_propname = "launchSecurity"
     remove_first = "type"
 
+    def set_policy_cb(self, inst, val, virtarg):
+        inst.policy = ""
+
+        try:
+            int(val, 16)
+        except ValueError as e:
+            fail(_("Invalid value for argument '%s' of --launch-security: %s") %
+                    (virtarg.propname, str(e)))
+
+        if not val.startswith("0x"):
+            inst.policy = "0x"
+
+        inst.policy = inst.policy + val
+
     @classmethod
     def _init_class(cls, **kwargs):
         VirtCLIParser._init_class(**kwargs)
         cls.add_arg("type", "type_")
         cls.add_arg("cbitpos", "cbitpos")
         cls.add_arg("reduced_phys_bits", "reduced_phys_bits")
-        cls.add_arg("policy", "policy")
+        cls.add_arg("policy", "policy", cb=cls.set_policy_cb)
         cls.add_arg("session", "session")
         cls.add_arg("dh_cert", "dh_cert")
 
@@ -3862,6 +3876,15 @@ class ParserLaunchSecurity(VirtCLIParser):
 
         if not type_:
             fail(_("Missing mandatory attribute 'type' for --launch-security"))
+        elif type_ == "sev":
+
+            # 'policy' is a mandatory 4-byte argument for the SEV firmware,
+            # if missing, let's use 0x03 which, according to the table at
+            # https://libvirt.org/formatdomain.html#launchSecurity:
+            # (bit 0) - disables the debugging mode
+            # (bit 1) - disables encryption key sharing across multiple guests
+            if 'policy' not in self.optdict:
+                self.optdict['policy'] = "0x03"
 
     def _parse(self, inst):
         if not inst.conn.is_qemu():
-- 
2.20.1