linux-kernel - Re: [PATCH 4.19 49/58] KVM: x86/pmu: Use AMD64_RAW_EVENT_MASK for PERF_TYPE

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Message-ID: <20220222153748.GB27262@amd>
Date:   Tue, 22 Feb 2022 16:37:48 +0100
From:   Pavel Machek <pavel@....cz>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Jim Mattson <jmattson@...gle.com>,
        David Dunn <daviddunn@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 4.19 49/58] KVM: x86/pmu: Use AMD64_RAW_EVENT_MASK for
 PERF_TYPE_RAW

Hi!

> [ Upstream commit 710c476514313c74045c41c0571bb5178fd16e3d ]
> 
> AMD's event select is 3 nybbles, with the high nybble in bits 35:32 of
> a PerfEvtSeln MSR. Don't mask off the high nybble when configuring a
> RAW perf event.

Ok, but this depends on b8bfee "KVM: x86/pmu: Don't truncate the
PerfEvtSeln MSR when creating a perf event", and that is backported to
5.10 but not 4.19... so we don't need this, either, right...?

Best regards,
								Pavel

> +++ b/arch/x86/kvm/pmu.c
> @@ -171,7 +171,7 @@ void reprogram_gp_counter(struct kvm_pmc *pmc, u64 eventsel)
>  	}
>  
>  	if (type == PERF_TYPE_RAW)
> -		config = eventsel & X86_RAW_EVENT_MASK;
> +		config = eventsel & AMD64_RAW_EVENT_MASK;
>  
>  	pmc_reprogram_counter(pmc, type, config,
>  			      !(eventsel & ARCH_PERFMON_EVENTSEL_USR),

-- 
http://www.livejournal.com/~pavelmachek

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