On Tue, 12 Jan 2021 09:15:26 +0100
Christian Borntraeger <borntraeger@xxxxxxxxxx> wrote:
> On 12.01.21 05:45, David Gibson wrote:
> > At least some s390 cpu models support "Protected Virtualization" (PV),
> > a mechanism to protect guests from eavesdropping by a compromised
> > hypervisor.
> >
> > This is similar in function to other mechanisms like AMD's SEV and
> > POWER's PEF, which are controlled by the "confidential-guest-support"
> > machine option. s390 is a slightly special case, because we already
> > supported PV, simply by using a CPU model with the required feature
> > (S390_FEAT_UNPACK).
> >
> > To integrate this with the option used by other platforms, we
> > implement the following compromise:
> >
> > - When the confidential-guest-support option is set, s390 will
> > recognize it, verify that the CPU can support PV (failing if not)
> > and set virtio default options necessary for encrypted or protected
> > guests, as on other platforms. i.e. if confidential-guest-support
> > is set, we will either create a guest capable of entering PV mode,
> > or fail outright.
> >
> > - If confidential-guest-support is not set, guests might still be
> > able to enter PV mode, if the CPU has the right model. This may be
> > a little surprising, but shouldn't actually be harmful.
> >
> > To start a guest supporting Protected Virtualization using the new
> > option use the command line arguments:
> > -object s390-pv-guest,id=pv0 -machine confidential-guest-support=pv0
>
>
> This results in
>
> [cborntra@t35lp61 qemu]$ qemu-system-s390x -enable-kvm -nographic -m 2G -kernel ~/full.normal
> **
> ERROR:../qom/object.c:317:type_initialize: assertion failed: (parent->instance_size <= ti->instance_size)
> Bail out! ERROR:../qom/object.c:317:type_initialize: assertion failed: (parent->instance_size <= ti->instance_size)
> Aborted (core dumped)
>
> > +static const TypeInfo s390_pv_guest_info = {
> > + .parent = TYPE_CONFIDENTIAL_GUEST_SUPPORT,
> > + .name = TYPE_S390_PV_GUEST,
> > + .instance_size = sizeof(S390PVGuestState),
> > + .interfaces = (InterfaceInfo[]) {
> > + { TYPE_USER_CREATABLE },
> > + { }
> > + }
> > +};
I think this needs TYPE_OBJECT in .parent and
TYPE_CONFIDENTIAL_GUEST_SUPPORT as an interface to fix the crash.
