linux-kernel - Re: [PATCH 3.16 045/305] x86/speculation: Apply IBPB more strictly to avoid cross-process data leak

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Message-ID: <b6c5883015ae25b2e87576b6295c328f5903ce5a.camel@decadent.org.uk>
Date:   Tue, 05 Feb 2019 01:13:25 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     Andi Kleen <ak@...ux.intel.com>, Jiri Kosina <jikos@...nel.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        WoodhouseDavid <dwmw@...zon.co.uk>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        SchauflerCasey <casey.schaufler@...el.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH 3.16 045/305] x86/speculation: Apply IBPB more strictly
 to avoid cross-process data leak

On Sun, 2019-02-03 at 13:37 -0800, Andi Kleen wrote:
> On Sun, Feb 03, 2019 at 08:05:53PM +0100, Jiri Kosina wrote:
> > On Sun, 3 Feb 2019, Ben Hutchings wrote:
> > 
> > > 3.16.63-rc1 review patch.  If anyone has any objections, please let me know.
> > > 
> > > ------------------
> > > 
> > > From: Jiri Kosina <jkosina@...e.cz>
> > > 
> > > commit dbfe2953f63c640463c630746cd5d9de8b2f63ae upstream.
> > 
> > You really want the whole IBPB+STIBP revamp from upstream, otherwise 
> > you're going to get noticeable performance penalties on some workloads 
> > with some microcodes.
> 
> Yes, we would need the opt-in/opt-out support too.
> 
> Please don't merge it just as is.

Thanks, I've now dropped this.

Ben.

-- 
Ben Hutchings
It is impossible to make anything foolproof
because fools are so ingenious.



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