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Date:   Tue, 19 May 2020 13:03:55 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Like Xu <like.xu@linux.intel.com>
Cc:     Paolo Bonzini <pbonzini@redhat.com>, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        Thomas Gleixner <tglx@linutronix.de>, ak@linux.intel.com,
        wei.w.wang@intel.com
Subject: Re: [PATCH v11 08/11] KVM: x86/pmu: Emulate LBR feature via guest
 LBR event
Message-ID: <20200519110355.GI279861@hirez.programming.kicks-ass.net>
References: <20200514083054.62538-1-like.xu@linux.intel.com>
 <20200514083054.62538-9-like.xu@linux.intel.com>
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On Thu, May 14, 2020 at 04:30:51PM +0800, Like Xu wrote:
> @@ -6698,6 +6698,7 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
>  
>  	if (vcpu_to_pmu(vcpu)->version)
>  		atomic_switch_perf_msrs(vmx);
> +
>  	atomic_switch_umwait_control_msr(vmx);
>  
>  	if (enable_preemption_timer)

Is this where the test to see if any of the KVM events went into ERROR
state should go?

	if (event->state == PERF_EVENT_STATE_ERROR) {
		pr_warn("unhappy, someone stole our counter\n");
	}

like..