Re: [PATCH RFC 0/2] arm: enable MTE for QEMU + kvm

[Cornelia Huck <cohuck@redhat.com>]

Friendly ping :)

On Thu, May 12 2022, Cornelia Huck <cohuck@redhat.com> wrote:

> This series enables MTE for kvm guests, if the kernel supports it.
> Lightly tested while running under the simulator (the arm64/mte/
> kselftests pass... if you wait patiently :)
>
> A new cpu property "mte" (defaulting to on if possible) is introduced;
> for tcg, you still need to enable mte at the machine as well.
>
> I've hacked up some very basic qtests; not entirely sure if I'm going
> about it the right way.
>
> Some things to look out for:
> - Migration is not (yet) supported. I added a migration blocker if we
>   enable mte in the kvm case. AFAIK, there isn't any hardware available
>   yet that allows mte + kvm to be used (I think the latest Gravitons
>   implement mte, but no bare metal instances seem to be available), so
>   that should not have any impact on real world usage.
> - I'm not at all sure about the interaction between the virt machine 'mte'
>   prop and the cpu 'mte' prop. To keep things working with tcg as before,
>   a not-specified mte for the cpu should simply give us a guest without
>   mte if it wasn't specified for the machine. However, mte on the cpu
>   without mte on the machine should probably generate an error, but I'm not
>   sure how to detect that without breaking the silent downgrade to preserve
>   existing behaviour.
> - As I'm still new to arm, please don't assume that I know what I'm doing :)
>
>
> Cornelia Huck (2):
>   arm/kvm: enable MTE if available
>   qtests/arm: add some mte tests
>
>  target/arm/cpu.c               | 18 +++-----
>  target/arm/cpu.h               |  4 ++
>  target/arm/cpu64.c             | 78 ++++++++++++++++++++++++++++++++++
>  target/arm/kvm64.c             |  5 +++
>  target/arm/kvm_arm.h           | 12 ++++++
>  target/arm/monitor.c           |  1 +
>  tests/qtest/arm-cpu-features.c | 31 ++++++++++++++
>  7 files changed, 137 insertions(+), 12 deletions(-)
>
> -- 
> 2.34.3