From: Andi Kleen <ak@linux.intel.com>
To: "Gonglei (Arei)" <arei.gonglei@huawei.com>
Cc: Wei Wang <wei.w.wang@intel.com>,
"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: Mon, 17 Sep 2018 19:56:16 -0700 [thread overview]
Message-ID: <20180918025616.GA10360@tassilo.jf.intel.com> (raw)
In-Reply-To: <33183CC9F5247A488A2544077AF19020DB0F1D5F@dggeml511-mbx.china.huawei.com>
> > 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.
-Andi
next prev parent reply other threads:[~2018-09-18 2:56 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 [this message]
2018-09-18 9:57 ` Wei Wang
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180918025616.GA10360@tassilo.jf.intel.com \
--to=ak@linux.intel.com \
--cc=arei.gonglei@huawei.com \
--cc=kan.liang@intel.com \
--cc=kvm@vger.kernel.org \
--cc=like.xu@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=pbonzini@redhat.com \
--cc=peterz@infradead.org \
--cc=rkrcmar@redhat.com \
--cc=wei.w.wang@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
Powered by JetHome