From: Wei Wang <wei.w.wang@intel.com>
To: Andi Kleen <ak@linux.intel.com>,
"Gonglei (Arei)" <arei.gonglei@huawei.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"pbonzini@redhat.com" <pbonzini@redhat.com>,
"kan.liang@intel.com" <kan.liang@intel.com>,
"peterz@infradead.org" <peterz@infradead.org>,
"mingo@redhat.com" <mingo@redhat.com>,
"rkrcmar@redhat.com" <rkrcmar@redhat.com>,
"like.xu@intel.com" <like.xu@intel.com>
Subject: Re: [PATCH v2 7/8] KVM: PMU: support to save/restore the guest lbr stack on vCPU switching
Date: Tue, 18 Sep 2018 17:57:50 +0800 [thread overview]
Message-ID: <5BA0CC1E.6030202@intel.com> (raw)
In-Reply-To: <20180918025616.GA10360@tassilo.jf.intel.com>
On 09/18/2018 10:56 AM, Andi Kleen wrote:
>>> From: Like Xu <like.xu@intel.com>
>>>
>>> This patch adds support to KVM to save/restore the lbr stack on vCPU
>>> context switching.
>>>
>>> When the guest sets the ACTIVE bit of MSR_KVM_PV_LBR_CTRL, a perf event
>>> is created on the host for the related vCPU. This perf event ensures the
>>> LBR stack to be saved/restored when the vCPU thread is scheduled out/in.
>>> The perf event is removed and freed when the guest clears the ACTIVE
>>> bit.
>>>
>> What about live migration? Does LBR stack need to be saved on the source side and
>> restored on the dest side with the passthrough mode?
> Yes it should. Either for call stack LBR, or when it is frozen/disabled.
>
> When it's not frozen/disabled and not in call stack LBR mode it likely doesn't
> hurt either, but it's not strictly needed because it will
> be replaced so quickly.
Yes, should be supported. We are working on v3 with the suggested lazy
save approach, and will send it out shortly.
Best,
Wei
next prev parent reply other threads:[~2018-09-18 9:53 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-06 11:30 [PATCH v2 0/8] Guest LBR Enabling Wei Wang
2018-09-06 11:30 ` [PATCH v2 1/8] perf/x86: add a function to get the lbr stack Wei Wang
2018-09-07 3:28 ` Andi Kleen
2018-09-07 6:45 ` Wei Wang
2018-09-06 11:30 ` [PATCH v2 2/8] KVM/x86: KVM_CAP_X86_GUEST_LBR Wei Wang
2018-09-06 11:30 ` [PATCH v2 3/8] KVM/vmx: Pass through the lbr stack to a guest Wei Wang
2018-09-06 11:30 ` [PATCH v2 4/8] KVM/x86: expose MSR_IA32_PERF_CAPABILITIES to the guest Wei Wang
2018-09-06 11:30 ` [PATCH v2 5/8] KVM/x86: enable the guest to access the debugctl msr Wei Wang
2018-09-06 11:30 ` [PATCH v2 6/8] perf/x86/intel/lbr: guest requesting KVM for lbr stack save/restore Wei Wang
2018-09-07 3:27 ` Andi Kleen
2018-09-07 5:24 ` Wei Wang
2018-09-07 14:10 ` Andi Kleen
2018-09-07 15:20 ` Wang, Wei W
2018-09-07 20:05 ` Andi Kleen
2018-09-08 1:34 ` Wang, Wei W
2018-09-06 11:30 ` [PATCH v2 7/8] KVM: PMU: support to save/restore the guest lbr stack on vCPU switching Wei Wang
2018-09-07 14:36 ` Jann Horn
2018-09-07 15:21 ` Wang, Wei W
2018-09-18 0:58 ` Gonglei (Arei)
2018-09-18 2:56 ` Andi Kleen
2018-09-18 9:57 ` Wei Wang [this message]
2018-09-18 10:34 ` Gonglei (Arei)
2018-09-06 11:30 ` [PATCH v2 8/8] perf/x86/intel/lbr: add the guest_lbr boolean to cpuc Wei Wang
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