Re: [PATCH v10 01/12] KVM: arm64: Allow userspace to get the writable masks for feature ID registers

[Oliver Upton <oliver.upton@linux.dev>]

On Thu, Sep 21, 2023 at 11:53:41AM +0200, Cornelia Huck wrote:
> On Wed, Sep 20 2023, Oliver Upton <oliver.upton@linux.dev> wrote:
> 
> > From: Jing Zhang <jingzhangos@google.com>
> >
> > While the Feature ID range is well defined and pretty large, it isn't
> > inconceivable that the architecture will eventually grow some other
> > ranges that will need to similarly be described to userspace.
> >
> > Add a VM ioctl to allow userspace to get writable masks for feature ID
> > registers in below system register space:
> > op0 = 3, op1 = {0, 1, 3}, CRn = 0, CRm = {0 - 7}, op2 = {0 - 7}
> > This is used to support mix-and-match userspace and kernels for writable
> > ID registers, where userspace may want to know upfront whether it can
> > actually tweak the contents of an idreg or not.
> >
> > Add a new capability (KVM_CAP_ARM_SUPPORTED_FEATURE_ID_RANGES) that
> > returns a bitmap of the valid ranges, which can subsequently be
> > retrieved, one at a time by setting the index of the set bit as the
> > range identifier.
> >
> > Suggested-by: Marc Zyngier <maz@kernel.org>
> > Suggested-by: Cornelia Huck <cohuck@redhat.com>
> > Signed-off-by: Jing Zhang <jingzhangos@google.com>
> 
> <process>I think you need to add your s-o-b here.</process>

Whoops, I thought I gave the right mix of flags to b4... clearly not.

> > ---
> >  arch/arm64/include/asm/kvm_host.h |  2 +
> >  arch/arm64/include/uapi/asm/kvm.h | 32 +++++++++++++++
> >  arch/arm64/kvm/arm.c              | 10 +++++
> >  arch/arm64/kvm/sys_regs.c         | 66 +++++++++++++++++++++++++++++++
> >  include/uapi/linux/kvm.h          |  2 +
> >  5 files changed, 112 insertions(+)
> 
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> 

Appreciated!

-- 
Thanks,
Oliver