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Date:   Mon, 14 Aug 2023 14:37:13 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Cc:     Borislav Petkov <bp@alien8.de>,
        Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
        x86@kernel.org
Subject: Re: [regression/bisected] Add IBPB decreases performance in two times
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On Mon, Aug 14, 2023 at 03:30:51AM +0500, Mikhail Gavrilov wrote:
> On Sun, Aug 13, 2023 at 7:19 PM Borislav Petkov <bp@alien8.de> wrote:
> > Nah, most people search the net and usually find the documentation, as
> > past experience shows. In this case, they will find:
> >
> > https://kernel.org/doc/html/latest/admin-guide/hw-vuln/srso.html
> >
> > It will be there next week but here's the source:
> >
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/admin-guide/hw-vuln/srso.rst
> >
> > --
> > Regards/Gruss,
> >     Boris.
> >
> > https://people.kernel.org/tglx/notes-about-netiquette
> 
> I am figure out why I noticed lage impact of safe RET on my system.
> safe-ret + KASAN = decrease performance for 50% in all scenarios
> I use KASAN on a daily basis to catch bugs.
> Is it possible for systems with KASAN to make a more optimal approach of SRSO?

Why do you care about speculation things on a dev box?