On Sun, Nov 13, 2022 at 8:38 AM Marc Zyngier wrote:
>
> For 64bit counters that overflow on a 32bit boundary, make
> sure we only check the bottom 32bit to generate a CHAIN event.
>
> Signed-off-by: Marc Zyngier
> ---
> arch/arm64/kvm/pmu-emul.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
> index d050143326b5..9e6bc7edc4de 100644
> --- a/arch/arm64/kvm/pmu-emul.c
> +++ b/arch/arm64/kvm/pmu-emul.c
> @@ -417,7 +417,8 @@ static void kvm_pmu_counter_increment(struct kvm_vcpu
> *vcpu,
> reg = lower_32_bits(reg);
> __vcpu_sys_reg(vcpu, PMEVCNTR0_EL0 + i) = reg;
>
> - if (reg) /* No overflow? move on */
> + /* No overflow? move on */
> + if (kvm_pmu_idx_has_64bit_overflow(vcpu, i) ? reg :
> lower_32_bits(reg))
A few lines up, the 'reg' is unconditionally updated with
"lower_32_bits(reg)". So, the change initially confused me
(until I checked the following patch). IMHO it might be more
clear if this patch and the next patch are folded into one patch.
Anyway:
Reviewed-by: Reiji Watanabe
Thank you,
Reiji
> continue;
>
> /* Mark overflow */
> --
> 2.34.1
>
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