[PATCH v2 11/14] KVM: arm64: PMU: Allow ID_AA64DFR0_EL1.PMUver to be set from userspace

[Marc Zyngier]

Hi Reiji,

On Fri, 04 Nov 2022 15:53:21 +0000,
Reiji Watanabe <reijiw at google.com> wrote:
> 
> BTW, if we have no intention of supporting a mix of vCPUs with and
> without PMU, I think it would be nice if we have a clear comment on
> that in the code.  Or I'm hoping to disallow it if possible though.

I'm not sure we're in a position to do this right now. The current API
has always (for good or bad reasons) been per-vcpu as it is tied to
the vcpu initialisation.

However, once we move to a sysreg-based API to control the vcpu
features, we can revisit this and say that some features have a
VM-wide effect if the vcpus have been created with some special flag
(or some other TBD mechanism).

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.