Re: [PATCH 06/11] KVM: arm64: nv: Acceletate EL0 counter accesses from hypervisor context

Oliver Upton
2024-12-05T17:08:08Z

On Thu, Dec 05, 2024 at 11:03:41AM +0000, Marc Zyngier wrote:
> On Thu, 05 Dec 2024 00:37:34 +0000,
> Oliver Upton <oliver.upton@linux.dev> wrote:
> >
> > typo: accelerate
>
> Huh, thanks!
>
> >
> > On Mon, Dec 02, 2024 at 05:21:29PM +0000, Marc Zyngier wrote:
>
> [...]
>
> > > + case SYS_CNTVCT_EL0:
> > > + case SYS_CNTVCTSS_EL0:
> > > + /* If !ELIsInHost(EL2), the guest's CNTVOFF_EL2 applies */
> >
> > !ELIsInHost(EL0)
>
> No, and that's the whole point. CNTVOFF_EL2 applies at all times when
> HCR_EL2==0 and that we're at EL2. From the pseudocode for CNTVCT_EL0:

Dammit, I don't know how many times I misread "CNTPCT" here rather than
CNTVCT. Sorry for the noise.

--
Thanks,
Oliver