[PATCH 59/89] KVM: arm64: Do not support MTE for protected VMs

[Fuad Tabba]

Hi Peter,

On Tue, Jun 7, 2022 at 1:42 AM Peter Collingbourne <pcc at google.com> wrote:
>
> On Thu, May 19, 2022 at 7:40 AM Will Deacon <will at kernel.org> wrote:
> >
> > From: Fuad Tabba <tabba at google.com>
> >
> > Return an error (-EINVAL) if trying to enable MTE on a protected
> > vm.
> >
> > Signed-off-by: Fuad Tabba <tabba at google.com>
> > ---
> >  arch/arm64/kvm/arm.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> > index 10e036bf06e3..8a1b4ba1dfa7 100644
> > --- a/arch/arm64/kvm/arm.c
> > +++ b/arch/arm64/kvm/arm.c
> > @@ -90,7 +90,9 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
> >                 break;
> >         case KVM_CAP_ARM_MTE:
> >                 mutex_lock(&kvm->lock);
> > -               if (!system_supports_mte() || kvm->created_vcpus) {
> > +               if (!system_supports_mte() ||
> > +                   kvm_vm_is_protected(kvm) ||
>
> Should this check be added to kvm_vm_ioctl_check_extension() as well?

No need. kvm_vm_ioctl_check_extension() calls pkvm_check_extension()
for protected vms, which functions as an allow list rather than a
block list.

Cheers,
/fuad


> Peter