linux-kernel - Re: [RFC PATCH 08/41] KVM: x86/pmu: Add get virtual LVTPC

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Message-ID: <Zhg4kkDzmdUiCYg8@google.com>
Date: Thu, 11 Apr 2024 12:22:58 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Xiong Zhang <xiong.y.zhang@...ux.intel.com>
Cc: pbonzini@...hat.com, peterz@...radead.org, mizhang@...gle.com, 
	kan.liang@...el.com, zhenyuw@...ux.intel.com, dapeng1.mi@...ux.intel.com, 
	jmattson@...gle.com, kvm@...r.kernel.org, linux-perf-users@...r.kernel.org, 
	linux-kernel@...r.kernel.org, zhiyuan.lv@...el.com, eranian@...gle.com, 
	irogers@...gle.com, samantha.alt@...el.com, like.xu.linux@...il.com, 
	chao.gao@...el.com, Xiong Zhang <xiong.y.zhang@...el.com>
Subject: Re: [RFC PATCH 08/41] KVM: x86/pmu: Add get virtual LVTPC_MASK bit function

On Fri, Jan 26, 2024, Xiong Zhang wrote:
> From: Xiong Zhang <xiong.y.zhang@...el.com>
> 
> On PMU passthrough mode, guest virtual LVTPC_MASK bit must be reflected
> onto HW, especially when guest clear it, the HW bit should be cleared also.
> Otherwise processor can't generate PMI until the HW mask bit is cleared.
> 
> This commit add a function to get virtual LVTPC_MASK bit, so that

No "This commit", "This patch", or any other variation.  Please read through:

  Documentation/process/maintainer-tip.rst 
  Documentation/process/maintainer-kvm-x86.rst

> it can be set onto HW later.
> 
> Signed-off-by: Xiong Zhang <xiong.y.zhang@...el.com>
> ---
>  arch/x86/kvm/lapic.h | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
> index e30641d5ac90..dafae44325d1 100644
> --- a/arch/x86/kvm/lapic.h
> +++ b/arch/x86/kvm/lapic.h
> @@ -277,4 +277,10 @@ static inline u8 kvm_xapic_id(struct kvm_lapic *apic)
>  {
>  	return kvm_lapic_get_reg(apic, APIC_ID) >> 24;
>  }
> +
> +static inline bool kvm_lapic_get_lvtpc_mask(struct kvm_vcpu *vcpu)
> +{
> +	return lapic_in_kernel(vcpu) &&
> +	       (kvm_lapic_get_reg(vcpu->arch.apic, APIC_LVTPC) & APIC_LVT_MASKED);
> +}

As suggested in the previous patch, I'm pretty sure we can safely omit this
helper.

>  #endif
> -- 
> 2.34.1
>