From: Paolo Bonzini <pbonzini@redhat.com>
To: Jian Zhou <jianjay.zhou@huawei.com>,
herongguang.he@huawei.com, zhang.zhanghailiang@huawei.com,
gleb@kernel.org, tglx@linutronix.de, mingo@redhat.com,
hpa@zytor.com, x86@kernel.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: weidong.huang@huawei.com, peter.huangpeng@huawei.com
Subject: Re: [PATCH] KVM: VMX: enable LBR virtualization
Date: Wed, 14 Oct 2015 13:30:16 +0200 [thread overview]
Message-ID: <561E3CC8.7080309@redhat.com> (raw)
In-Reply-To: <561E3BDB.4080904@huawei.com>
On 14/10/2015 13:26, Jian Zhou wrote:
> On 12/10/2015 20:44, Paolo Bonzini wrote:
>> In addition, the MSR numbers may differ between the guest and the host,
>> because it is possible to emulate e.g. a Core CPU on a Core 2 CPU. So I
>> recommend against using the atomic switch mechanism for the from/to MSRs.
>
> The vLBR feature depends on vPMU, and to enable vPMU, it needs to
> specify the "cpu mode" in the guest XML as host-passthrough. I think
> the MSR numbers between the guest and the host are the same in this
> senario.
Does it depend on vPMU _for Linux guests_ or in general? My impression
is that LBR can be used by the guest independent of the PMU. You should
also write a unit test for kvm-unit-tests to test the behavior of your
implementation.
Thanks,
Paolo
next prev parent reply other threads:[~2015-10-14 11:30 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1444471906-8496-1-git-send-email-jianjay.zhou@huawei.com>
2015-10-12 12:10 ` [PATCH] KVM: VMX: enable LBR virtualization Jian Zhou
2015-10-12 12:44 ` Paolo Bonzini
2015-10-14 11:26 ` Jian Zhou
2015-10-14 11:30 ` Paolo Bonzini [this message]
2015-10-15 13:51 ` Jian Zhou
2015-10-15 15:03 ` Paolo Bonzini
2015-10-16 0:54 ` Jian Zhou
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