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From: David Woodhouse <dwmw2@infradead.org>
To: Dexuan-Linux Cui <dexuan.linux@gmail.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>,
	pbonzini@redhat.com, rkrcmar@redhat.com, tglx@linutronix.de,
	mingo@redhat.com, hpa@zytor.com, dave.hansen@linux.intel.com,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	x86@kernel.org, arjan@linux.intel.com, decui@microsoft.com
Subject: Re: tip/master falls off NOP cliff with KPTI under KVM
Date: Thu, 25 Jan 2018 07:53:21 +0000	[thread overview]
Message-ID: <1516866801.30244.3.camel@infradead.org> (raw)
In-Reply-To: <CAA42JLZe+_dCcbam-_KE-kGYCHbZ2OCyJTHV02yznwrdJVJ2hg@mail.gmail.com>

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On Wed, 2018-01-24 at 16:53 -0800, Dexuan-Linux Cui wrote:
> On Wed, Jan 10, 2018 at 2:53 PM, Woodhouse, David <dwmw@amazon.co.uk> wrote:
> > 
> > On Thu, 2018-01-11 at 01:34 +0300, Alexey Dobriyan wrote:
> > > 
> > > 
> > > Bisection points to
> > > 
> > >         f3433c1010c6af61c9897f0f0447f81b991feac1 is the first bad commit
> > >         commit f3433c1010c6af61c9897f0f0447f81b991feac1
> > >         Author: David Woodhouse <dwmw@amazon.co.uk>
> > >         Date:   Tue Jan 9 14:43:11 2018 +0000
> > > 
> > >             x86/retpoline/entry: Convert entry assembler indirect jumps
> > Thanks. We've fixed the underlying problem with the alternatives
> > mechanism, *and* changed the retpoline code not to actually rely on
> > said fix.
> Hi David and all,
> It looks the latest upstream tree did fix the issue.
> Can you please specify the related commit(s) that fixed the issue?
> I need to cherry-pick the fix. I suppose a quick reply from you would save
>  me a lot of time. :-)

Hi Dexuan,

The above commit didn't ever make it into Linus' tree in that form; the
issues were fixed beforehand. So there isn't a subsequent commit that
fixes it. I think it might have just been removing some .align 16 from
nospec-branch.h?

The correct version has been backported to 4.9 and 4.4 releases
already; if you pulled in an early version directly from tip/x86/pti
then I'd recommend you drop it and pull in the real version instead.

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  reply	other threads:[~2018-01-25  7:53 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-10 22:08 Alexey Dobriyan
2018-01-10 22:34 ` Alexey Dobriyan
2018-01-10 22:53   ` Woodhouse, David
2018-01-25  0:53     ` Dexuan-Linux Cui
2018-01-25  7:53       ` David Woodhouse [this message]
2018-01-25 19:00         ` Dexuan Cui
2018-01-25 19:13           ` Thomas Gleixner
2018-01-25 19:35             ` Dexuan-Linux Cui

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