Re: [PATCH v7 8/10] KVM: arm64: Add capability to advertise ptrauth for guest

[Amit Daniel Kachhap]

Hi,

On 3/26/19 1:35 AM, Kristina Martsenko wrote:
> On 19/03/2019 08:30, Amit Daniel Kachhap wrote:
> > This patch advertises the capability of pointer authentication
> > when system supports pointer authentication and VHE mode present.
> >
> > Signed-off-by: Amit Daniel Kachhap <amit.kachhap@xxxxxxx>
> > Cc: Mark Rutland <mark.rutland@xxxxxxx>
> > Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
> > Cc: Christoffer Dall <christoffer.dall@xxxxxxx>
> > Cc: kvmarm@xxxxxxxxxxxxxxxxxxxxx
> > ---
> >   arch/arm64/kvm/reset.c   | 4 ++++
> >   include/uapi/linux/kvm.h | 1 +
> >   2 files changed, 5 insertions(+)
> >
> > diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
> > index 00f0639..a3b269e 100644
> > --- a/arch/arm64/kvm/reset.c
> > +++ b/arch/arm64/kvm/reset.c
> > @@ -92,6 +92,10 @@ int kvm_arch_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> >   	case KVM_CAP_ARM_VM_IPA_SIZE:
> >   		r = kvm_ipa_limit;
> >   		break;
> > +	case KVM_CAP_ARM_PTRAUTH:
> > +		r = has_vhe() && system_supports_address_auth() &&
> > +			system_supports_generic_auth();
> > +		break;
> >   	default:
> >   		r = 0;
> >   	}
> > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> > index 6d4ea4b..a553477 100644
> > --- a/include/uapi/linux/kvm.h
> > +++ b/include/uapi/linux/kvm.h
> > @@ -988,6 +988,7 @@ struct kvm_ppc_resize_hpt {
> >   #define KVM_CAP_ARM_VM_IPA_SIZE 165
> >   #define KVM_CAP_MANUAL_DIRTY_LOG_PROTECT 166
> >   #define KVM_CAP_HYPERV_CPUID 167
> > +#define KVM_CAP_ARM_PTRAUTH 168
>
> Since we now have two separate vcpu flags, then I think we also need two
> capabilities here (one for address auth and one for generic auth). This
> will allow us to support the features separately in the future if we
> need to.
I have no objection to your suggestion. Infact all other KVM_ARM_VCPU_* 
features have there own capability defined. I will check other 
architectures if they define separate capability for major/minor features.

Thanks,
Amit D
> Thanks,
> Kristina