From: Sean Christopherson <seanjc@google.com>
To: Sean Christopherson <seanjc@google.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org, Mingwei Zhang <mizhang@google.com>,
Jim Mattson <jmattson@google.com>
Subject: Re: [PATCH 0/3] KVM: VMX: Disable LBRs if CPU doesn't have callstacks
Date: Mon, 8 Apr 2024 19:01:33 -0700 [thread overview]
Message-ID: <171262750089.1420807.14858434543826601467.b4-ty@google.com> (raw)
In-Reply-To: <20240307011344.835640-1-seanjc@google.com>
On Wed, 06 Mar 2024 17:13:41 -0800, Sean Christopherson wrote:
> Disable LBR virtualization if the CPU (or I guess perf) doesn't support
> LBR callstacks, as KVM unconditionally creates the associated perf LBR
> event with PERF_SAMPLE_BRANCH_CALL_STACK. That results in perf rejecting
> the event, and cause LBR virtualization to silently fail.
>
> This was detected by running vmx_pmu_caps_test on older hardware. I didn't
> tag it for stable because I can't imagine anyone is trying to use KVM's LBR
> virtualization on pre-HSW.
>
> [...]
Applied to kvm-x86 fixes, as I can't imagine anyone objecting to patch 2.
[1/3] KVM: VMX: Snapshot LBR capabilities during module initialization
https://github.com/kvm-x86/linux/commit/2a94a2761236
[2/3] perf/x86/intel: Expose existence of callback support to KVM
https://github.com/kvm-x86/linux/commit/0c0241c12332
[3/3] KVM: VMX: Disable LBR virtualization if the CPU doesn't support LBR callstacks
https://github.com/kvm-x86/linux/commit/0eb2416c8111
--
https://github.com/kvm-x86/linux/tree/next
prev parent reply other threads:[~2024-04-09 2:02 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-07 1:13 [PATCH 0/3] KVM: VMX: Disable LBRs if CPU doesn't have callstacks Sean Christopherson
2024-03-07 1:13 ` [PATCH 1/3] KVM: VMX: Snapshot LBR capabilities during module initialization Sean Christopherson
2024-03-18 22:50 ` Mingwei Zhang
2024-03-07 1:13 ` [PATCH 2/3] perf/x86/intel: Expose existence of callback support to KVM Sean Christopherson
2024-03-18 22:50 ` Mingwei Zhang
2024-03-07 1:13 ` [PATCH 3/3] KVM: VMX: Disable LBR virtualization if the CPU doesn't support LBR callstacks Sean Christopherson
2024-03-18 22:51 ` Mingwei Zhang
2024-04-09 2:01 ` Sean Christopherson [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=171262750089.1420807.14858434543826601467.b4-ty@google.com \
--to=seanjc@google.com \
--cc=acme@kernel.org \
--cc=jmattson@google.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-perf-users@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=mizhang@google.com \
--cc=namhyung@kernel.org \
--cc=pbonzini@redhat.com \
--cc=peterz@infradead.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.