Re: [PATCH v7 03/12] KVM: arm64: PMU: Clear PM{C,I}NTEN{SET,CLR} and PMOVS{SET,CLR} on vCPU reset

[Oliver Upton]

On Wed, Oct 18, 2023 at 02:16:36PM -0700, Raghavendra Rao Ananta wrote:

[...]

> I had a brief discussion about this with Oliver, and it looks like we
> might need a couple of additional changes for these register accesses:
> - For the userspace accesses, we have to implement explicit get_user
> and set_user callbacks that to filter out the unimplemented counters
> using kvm_pmu_valid_counter_mask().
> - For the guest accesses to be correct, we might have to apply the
> same mask while serving KVM_REQ_RELOAD_PMU.

To be precise, the second issue is that we want to make sure KVM's PMU
emulation never uses an invalid value for the configuration, like
enabling a PMC at an index inaccessible to the guest.

-- 
Thanks,
Oliver