Re: [PATCH v6 05/16] KVM: x86/pmu: Introduce the ctrl_mask value for fixed counter

[Peter Zijlstra]

On Tue, May 11, 2021 at 10:42:03AM +0800, Like Xu wrote:
> The mask value of fixed counter control register should be dynamic
> adjusted with the number of fixed counters. This patch introduces a
> variable that includes the reserved bits of fixed counter control
> registers. This is needed for later Ice Lake fixed counter changes.
> 
> Co-developed-by: Luwei Kang <luwei.kang@xxxxxxxxx>
> Signed-off-by: Luwei Kang <luwei.kang@xxxxxxxxx>
> Signed-off-by: Like Xu <like.xu@xxxxxxxxxxxxxxx>
> ---
>  arch/x86/include/asm/kvm_host.h | 1 +
>  arch/x86/kvm/vmx/pmu_intel.c    | 6 +++++-
>  2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 55efbacfc244..49b421bd3dd8 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -457,6 +457,7 @@ struct kvm_pmu {
>  	unsigned nr_arch_fixed_counters;
>  	unsigned available_event_types;
>  	u64 fixed_ctr_ctrl;
> +	u64 fixed_ctr_ctrl_mask;
>  	u64 global_ctrl;
>  	u64 global_status;
>  	u64 global_ovf_ctrl;
> diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
> index d9dbebe03cae..ac7fe714e6c1 100644
> --- a/arch/x86/kvm/vmx/pmu_intel.c
> +++ b/arch/x86/kvm/vmx/pmu_intel.c
> @@ -400,7 +400,7 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>  	case MSR_CORE_PERF_FIXED_CTR_CTRL:
>  		if (pmu->fixed_ctr_ctrl == data)
>  			return 0;
> -		if (!(data & 0xfffffffffffff444ull)) {
> +		if (!(data & pmu->fixed_ctr_ctrl_mask)) {

Don't we already have hardware with more than 3 fixed counters?