From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
To: Jon Kohler <jon@nutanix.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@alien8.de>,
Peter Zijlstra <peterz@infradead.org>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
X86 ML <x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
LKML <linux-kernel@vger.kernel.org>,
"kvm @ vger . kernel . org" <kvm@vger.kernel.org>,
chao.gao@intel.com
Subject: Re: [PATCH] x86/bhi: avoid hardware mitigation for 'spectre_bhi=vmexit'
Date: Thu, 12 Sep 2024 09:24:40 -0700 [thread overview]
Message-ID: <20240912162440.be23sgv5v5ojtf3q@desk> (raw)
In-Reply-To: <070B4F7E-5103-4C1B-B901-01CE7191EB9A@nutanix.com>
On Thu, Sep 12, 2024 at 03:44:38PM +0000, Jon Kohler wrote:
> > It is only worth implementing the long sequence in VMEXIT_ONLY mode if it is
> > significantly better than toggling the MSR.
>
> Thanks for the pointer! I hadn’t seen that second sequence. I’ll do measurements on
> three cases and come back with data from an SPR system.
> 1. as-is (wrmsr on entry and exit)
> 2. Short sequence (as a baseline)
> 3. Long sequence
I wonder if virtual SPEC_CTRL feature introduced in below series can
provide speedup, as it can replace the MSR toggling with faster VMCS
operations:
https://lore.kernel.org/kvm/20240410143446.797262-1-chao.gao@intel.com/
Adding Chao for their opinion.
next prev parent reply other threads:[~2024-09-12 16:24 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-12 14:11 Jon Kohler
2024-09-12 15:14 ` Pawan Gupta
2024-09-12 15:44 ` Jon Kohler
2024-09-12 16:24 ` Pawan Gupta [this message]
2024-09-13 5:28 ` Chao Gao
2024-09-13 15:51 ` Jon Kohler
2024-09-13 17:33 ` Pawan Gupta
2024-09-13 18:01 ` Jon Kohler
2024-09-13 18:39 ` Jim Mattson
2024-09-13 23:04 ` Jim Mattson
2024-09-14 0:16 ` Pawan Gupta
2024-09-14 2:35 ` Jim Mattson
2024-09-13 5:39 ` Chao Gao
2024-09-13 15:52 ` Jon Kohler
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=20240912162440.be23sgv5v5ojtf3q@desk \
--to=pawan.kumar.gupta@linux.intel.com \
--cc=bp@alien8.de \
--cc=chao.gao@intel.com \
--cc=dave.hansen@linux.intel.com \
--cc=hpa@zytor.com \
--cc=jon@nutanix.com \
--cc=jpoimboe@kernel.org \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®