From: Paolo Bonzini <pbonzini@redhat.com>
To: "H. Peter Anvin" <hpa@zytor.com>,
Venkatesh Srinivas <venkateshs@google.com>,
Peter Wu <peter@lekensteyn.nl>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>, Andi Kleen <ak@linux.intel.com>,
Linux Kernel Developers List <linux-kernel@vger.kernel.org>,
kvm@vger.kernel.org, Gleb Natapov <gleb@kernel.org>
Subject: Re: GPF in intel_pmu_lbr_reset() with qemu -cpu host
Date: Sat, 22 Mar 2014 08:54:10 +0100 [thread overview]
Message-ID: <532D41A2.40404@redhat.com> (raw)
In-Reply-To: <57783d0c-3e75-47e1-a22a-818ad12e5f5c@email.android.com>
Il 21/03/2014 20:09, H. Peter Anvin ha scritto:
> Calling this a bug in the PMU code is ridiculous. If KVM tells the
> system it os a specific vendor-family-model-stepping but diverges in
> behavior then it, by definition, is broken.
Yeah, this is true. On AMD there is processor support for virtualizing
LBR, but Intel doesn't have it. I'm not sure if generic load/save MSR
support could be used to do it.
Unfortunately, LBR does not have any CPUID bit to show its presence,
unlike a lot of other perf-related features. So, even though calling it
a bug in perf code is an exaggeration, using rdmsr_safe makes sense.
Paolo
next prev parent reply other threads:[~2014-03-22 7:54 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-21 17:42 GPF in intel_pmu_lbr_reset() with qemu -cpu host Peter Wu
2014-03-21 17:46 ` Peter Wu
2014-03-21 19:04 ` Venkatesh Srinivas
2014-03-21 19:09 ` H. Peter Anvin
2014-03-22 7:54 ` Paolo Bonzini [this message]
2014-03-22 8:50 ` Gleb Natapov
2014-03-22 10:05 ` Peter Wu
2014-03-22 12:27 ` Gleb Natapov
2014-03-22 21:46 ` H. Peter Anvin
2014-03-22 22:00 ` Peter Wu
2014-03-26 7:23 ` Wu, Feng
2014-03-26 9:38 ` Paolo Bonzini
2014-03-21 19:29 ` Andi Kleen
2014-03-21 20:46 ` H. Peter Anvin
2014-03-21 21:37 ` Andi Kleen
2014-03-21 21:41 ` H. Peter Anvin
2014-03-21 21:48 ` Andi Kleen
2014-03-21 21:55 ` H. Peter Anvin
2014-03-22 0:22 ` Andi Kleen
2014-03-22 0:26 ` H. Peter Anvin
2014-03-22 0:30 ` Andi Kleen
2014-03-22 0:34 ` H. Peter Anvin
2014-03-22 10:01 ` Borislav Petkov
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