linux-kernel - Re: [PATCH v6 05/16] KVM: x86/pmu: Introduce the ctrl

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Message-ID: <YKImwdg7LO/OPvVJ@hirez.programming.kicks-ass.net>
Date:   Mon, 17 May 2021 10:18:09 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Like Xu <like.xu@...ux.intel.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Borislav Petkov <bp@...en8.de>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, weijiang.yang@...el.com,
        Kan Liang <kan.liang@...ux.intel.com>, ak@...ux.intel.com,
        wei.w.wang@...el.com, eranian@...gle.com, liuxiangdong5@...wei.com,
        linux-kernel@...r.kernel.org, x86@...nel.org, kvm@...r.kernel.org,
        Luwei Kang <luwei.kang@...el.com>
Subject: Re: [PATCH v6 05/16] KVM: x86/pmu: Introduce the ctrl_mask value for
 fixed counter

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@...el.com>
> Signed-off-by: Luwei Kang <luwei.kang@...el.com>
> Signed-off-by: Like Xu <like.xu@...ux.intel.com>
> ---
>  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?