From: "Radim Krčmář" <rkrcmar@redhat.com>
To: kmeaw@yandex-team.ru
Cc: "Gabriel L. Somlo" <gsomlo@gmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"gleb@kernel.org" <gleb@kernel.org>,
"pbonzini@redhat.com" <pbonzini@redhat.com>
Subject: Re: [PATCH] KVM: Handle MSR_IA32_PERF_CTL
Date: Fri, 27 May 2016 17:22:25 +0200 [thread overview]
Message-ID: <20160527152224.GA11721@potion> (raw)
In-Reply-To: <920591464331762@webcorp02f.yandex-team.ru>
2016-05-27 09:49+0300, kmeaw@yandex-team.ru:
> 26.05.2016, 23:44, "Gabriel L. Somlo" <gsomlo@gmail.com>:
>> On Thu, May 26, 2016 at 10:39:31PM +0200, Radim Krčmář wrote:
>>> 2016-05-26 10:32+0300, kmeaw@yandex-team.ru:
>>> > This patch implements a dummy handler for MSR_IA32_PERF_CTL to avoid the
>>> > crashes. Most notably it fixes an issue with MacOS X 10.10 kernel.
>>> Does MacOS X write it too?
>>
>> After setting /sys/module/kvm/parameters/ignore_msrs, all I get in
>> dmesg after firing up OS X is:
>>
>> vcpu0 ignored rdmsr: 0x199
>>
>> So no, I don't think it would try to write it.
>
> That's right, OS X does not issue an wrmsr to 0x199. More specifically, I have not
> observed that on my KVM instances. Should I remove the "wrmsr" portion from the
> patch?
Yes, please. Silently ignoring the write is worse than #GP and #GP is
not a problem, so I wouldn't bother with a phony implementation.
Returning 0 on read is ok as seems to mean P-state=0, which is within
expectations.
(I wonder why MacOS X doesn't read IA32_PERF_STATUS, though.)
next prev parent reply other threads:[~2016-05-27 15:22 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-26 7:32 [PATCH] KVM: Handle MSR_IA32_PERF_CTL kmeaw
2016-05-26 20:39 ` Radim Krčmář
2016-05-26 20:44 ` Gabriel L. Somlo
[not found] ` <920591464331762@webcorp02f.yandex-team.ru>
2016-05-27 15:22 ` Radim Krčmář [this message]
2016-05-27 15:38 ` Radim Krčmář
2016-05-31 7:53 ` Paolo Bonzini
2016-05-31 13:05 ` Radim Krčmář
[not found] ` <1317601464689200@webcorp01d.yandex-team.ru>
2016-05-31 13:16 ` [PATCH v3] " Radim Krčmář
2016-05-31 14:38 ` [PATCH] " Dmitry Bilunov
2016-05-31 14:57 ` Radim Krčmář
2016-05-27 15:28 ` Radim Krčmář
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