On Wed, Jan 13, 2021 at 07:57:41AM +0100, Christian Borntraeger wrote:
>
>
> On 13.01.21 01:57, David Gibson wrote:
> > On Tue, Jan 12, 2021 at 12:36:07PM +0100, Cornelia Huck wrote:
> > 65;6201;1c> 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.
> >
> > No, that was true of an earlier revision, but parent is correct in the
> > current version.
>
> right now parent is obviously wrong as it triggers the above warning (and all other
> variants in the previous patches also use TYPE_OBJECT). It is probably the right
> thing when you fix
>
> +struct S390PVGuestState {
> + Object parent_obj;
> +};
> +
>
> and change Object to the proper type I guess.
Yes, I think so. In the next spin I've fixed the parent_obj field (as
well as moving to OBJECT_DEFINE_TYPE()) and it's passing the gitlab
CI, at least.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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