All of lore.kernel.org
 help / color / mirror / Atom feed
From: Jim Mattson <jmattson@google.com>
To: Like Xu <like.xu.linux@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Sean Christopherson <seanjc@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Joerg Roedel <joro@8bytes.org>,
	ak@linux.intel.com, wei.w.wang@intel.com, kan.liang@intel.com,
	alex.shi@linux.alibaba.com, kvm@vger.kernel.org, x86@kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v14 00/11] KVM: x86/pmu: Guest Last Branch Recording Enabling
Date: Mon, 19 Sep 2022 11:08:28 -0700	[thread overview]
Message-ID: <CALMp9eRAv_7UOL8K+15_UsV9ML5M3rnh-Rz2C1GtTkZCHt4Yjg@mail.gmail.com> (raw)
In-Reply-To: <ec0f97e9-33b7-61d8-25b8-50175544dbdd@gmail.com>

On Mon, Sep 19, 2022 at 12:26 AM Like Xu <like.xu.linux@gmail.com> wrote:
>
> On 14/9/2022 7:42 am, Jim Mattson wrote:
> > How does live migration work? I don't see any mechanism for recording
> > the current LBR MSRs on suspend or restoring them on resume.
>
> Considering that LBR is still a model specific feature, migration is less
> valuable unless
> both LBR_FMT values of the migration side are the same, the compatibility check
> (based on cpu models) is required (gathering dust in my to-do list);

This seems like a problem best solved in the control plane.

> and there is another dusty missing piece is how to ensure that vcpu can get LBR
> hardware in
> vmx transition when KVM lbr event fails in host lbr event competition, the
> complexity here is
> that the host and guest may have different LBR filtering options.

In case of a conflict, who currently wins? The host or the guest? I'd
like the guest to win, but others may feel differently. Maybe we need
a configuration knob?

> The good news is the Architecture LBR will add save/restore support since Paolo
> is not averse to
> putting more msr's into msrs_to_save_all[], perhaps a dynamic addition mechanism
> is a prerequisite.
>
> Please let me know what your priority preferences are for these tasks above.

      reply	other threads:[~2022-09-19 18:10 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-01  5:10 [PATCH v14 00/11] KVM: x86/pmu: Guest Last Branch Recording Enabling Like Xu
2021-02-01  5:10 ` [PATCH v14 01/11] KVM: x86/vmx: Make vmx_set_intercept_for_msr() non-static Like Xu
2021-02-01  5:10 ` [PATCH v14 02/11] KVM: x86/pmu: Set up IA32_PERF_CAPABILITIES if PDCM bit is available Like Xu
2021-02-02 11:48   ` Paolo Bonzini
2021-02-01  5:10 ` [PATCH v14 03/11] KVM: vmx/pmu: Add PMU_CAP_LBR_FMT check when guest LBR is enabled Like Xu
2021-02-02 12:00   ` Paolo Bonzini
2021-02-01  5:10 ` [PATCH v14 04/11] KVM: vmx/pmu: Expose DEBUGCTLMSR_LBR in the MSR_IA32_DEBUGCTLMSR Like Xu
2021-02-01  5:10 ` [PATCH v14 05/11] KVM: vmx/pmu: Create a guest LBR event when vcpu sets DEBUGCTLMSR_LBR Like Xu
2021-02-01  5:10 ` [PATCH v14 06/11] KVM: vmx/pmu: Pass-through LBR msrs when the guest LBR event is ACTIVE Like Xu
2021-02-01  5:10 ` [PATCH v14 07/11] KVM: vmx/pmu: Reduce the overhead of LBR pass-through or cancellation Like Xu
2021-02-01  5:10 ` [PATCH v14 08/11] KVM: vmx/pmu: Emulate legacy freezing LBRs on virtual PMI Like Xu
2021-02-01  5:10 ` [PATCH v14 09/11] KVM: vmx/pmu: Release guest LBR event via lazy release mechanism Like Xu
2021-02-01  5:10 ` [PATCH v14 10/11] KVM: vmx/pmu: Expose LBR_FMT in the MSR_IA32_PERF_CAPABILITIES Like Xu
2021-02-01  5:10 ` [PATCH v14 11/11] selftests: kvm/x86: add test for pmu msr MSR_IA32_PERF_CAPABILITIES Like Xu
2021-02-01  6:01 ` [PATCH v14 07/11] KVM: vmx/pmu: Reduce the overhead of LBR pass-through or cancellation Like Xu
2021-02-01  6:01   ` [PATCH v14 08/11] KVM: vmx/pmu: Emulate legacy freezing LBRs on virtual PMI Like Xu
2021-02-01  6:01   ` [PATCH v14 09/11] KVM: vmx/pmu: Release guest LBR event via lazy release mechanism Like Xu
2021-02-01  6:01   ` [PATCH v14 10/11] KVM: vmx/pmu: Expose LBR_FMT in the MSR_IA32_PERF_CAPABILITIES Like Xu
2021-02-01  6:01   ` [PATCH v14 11/11] selftests: kvm/x86: add test for pmu msr MSR_IA32_PERF_CAPABILITIES Like Xu
2021-02-02 14:53     ` Paolo Bonzini
2021-02-02 12:37 ` [PATCH v14 00/11] KVM: x86/pmu: Guest Last Branch Recording Enabling Paolo Bonzini
2021-07-29 12:40 ` Liuxiangdong
2021-07-30  3:15   ` Liuxiangdong
2021-07-30  3:28     ` Like Xu
2022-09-13 23:42 ` Jim Mattson
2022-09-19  7:26   ` Like Xu
2022-09-19 18:08     ` Jim Mattson [this message]

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=CALMp9eRAv_7UOL8K+15_UsV9ML5M3rnh-Rz2C1GtTkZCHt4Yjg@mail.gmail.com \
    --to=jmattson@google.com \
    --cc=ak@linux.intel.com \
    --cc=alex.shi@linux.alibaba.com \
    --cc=joro@8bytes.org \
    --cc=kan.liang@intel.com \
    --cc=kvm@vger.kernel.org \
    --cc=like.xu.linux@gmail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=pbonzini@redhat.com \
    --cc=seanjc@google.com \
    --cc=vkuznets@redhat.com \
    --cc=wanpengli@tencent.com \
    --cc=wei.w.wang@intel.com \
    --cc=x86@kernel.org \
    /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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.