Re: [libvirt PATCH v3 13/13] qemu: format sev-guest.kernel-hashes property

On Fri, Dec 10, 2021 at 16:47:13 +0000, Daniel P. Berrangé wrote: > Set the kernel-hashes property on the sev-guest object if > the config asked for it explicitly. While QEMU machine > types currently default to having this setting off, it > is not guaranteed to remain this way. > > Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; > --- > src/qemu/qemu_command.c | 1 + > src/qemu/qemu_validate.c | 7 ++++ > ...unch-security-sev-direct.x86_64-6.2.0.args | 40 +++++++++++++++++++ > .../launch-security-sev-direct.xml | 39 ++++++++++++++++++ > tests/qemuxml2argvtest.c | 1 + > 5 files changed, 88 insertions(+) > create mode 100644 tests/qemuxml2argvdata/launch-security-sev-direct.x86_64-6.2.0.args > create mode 100644 tests/qemuxml2argvdata/launch-security-sev-direct.xml > > diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c > index 613f7a5d2a..dfbf4973f5 100644 > --- a/src/qemu/qemu_command.c > +++ b/src/qemu/qemu_command.c > @@ -9894,6 +9894,7 @@ qemuBuildSEVCommandLine(virDomainObj *vm, virCommand *cmd, > "u:policy", sev->policy, > "S:dh-cert-file", dhpath, > "S:session-file", sessionpath, > + "T:kernel-hashes", sev->kernel_hashes, Since this is an '-object' ... > NULL) < 0) > return -1; > > diff --git a/src/qemu/qemu_validate.c b/src/qemu/qemu_validate.c > index 29b01495ad..c0dc1f7b53 100644 > --- a/src/qemu/qemu_validate.c > +++ b/src/qemu/qemu_validate.c > @@ -1200,6 +1200,13 @@ qemuValidateDomainDef(const virDomainDef *def, > "this QEMU binary")); > return -1; > } > + > + if (def->sec->data.sev.kernel_hashes == VIR_TRISTATE_BOOL_YES && > + !virQEMUCapsGet(qemuCaps, QEMU_CAPS_SEV_GUEST_KERNEL_HASHES)) { ... and this flag means that the 'sev-guest' actually has the 'kernel-hashes' property, the above check should be if (def->sec->data.sev.kernel_hashes != VIR_TRISTATE_BOOL_ABSENT && ...

as an explicit disable will also cause a qemu error when the property is not defined inside sev-guest. Other option is to use 'B:kernel-hashes' above and extract the value of sev->kernel_hashes into a temporary bool initialized to false via virTristateBoolToBool which preserves the default. In such case it will be always omitted when not enabled. Reviewed-by: Peter Krempa <pkrempa(a)redhat.com&gt;