linux-kernel - Re: [PATCH 00/45] arm Spectre fix backport review for LTS 4.9

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Message-ID: <20180308170153.376gcwwudwkq3gs7@pali>
Date:   Thu, 8 Mar 2018 18:01:53 +0100
From:   Pali Rohár <pali.rohar@...il.com>
To:     Marc Zyngier <marc.zyngier@....com>
Cc:     Pavel Machek <pavel@....cz>, Alex Shi <alex.shi@...aro.org>,
        sre@...nel.org, linux-omap@...r.kernel.org, tony@...mide.com,
        khilman@...nel.org, aaro.koskinen@....fi,
        ivo.g.dimitrov.75@...il.com, patrikbachan@...il.com,
        serge@...lyn.com, abcloriens@...il.com, clayton@...ftyguy.net,
        martijn@...xit.nl, sakari.ailus@...ux.intel.com,
        Filip Matijević <filip.matijevic.pz@...il.com>,
        Will Deacon <will.deacon@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Catalin Marinas <catalin.marinas@....com>,
        stable@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 00/45] arm Spectre fix backport review for LTS 4.9

On Thursday 08 March 2018 13:35:49 Marc Zyngier wrote:
> On 08/03/18 13:21, Pali Rohár wrote:
> > On Thursday 08 March 2018 13:27:15 Pavel Machek wrote:
> >> Hi!
> >>
> >>> Resent without non-upstream patches.
> >>>
> >>> This backport patchset fixed the spectre issue, it's original branch:
> >>> https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git/log/?h=kpti
> >>> A few dependency or fixingpatches are also picked up, if they are necessary
> >>>  and no functional changes.
> >>>
> >>> No bug found from kernelci.org and lkft testing. It also could be gotten from:
> >>>
> >>> git://git.linaro.org/kernel/linux-linaro-stable.git v4.9-spectre-upstream-only
> >>>
> >>> Comments are appreciated!
> >>
> >> Not entirely related to this patched, but... I have few older ARM
> >> boards here, and Nokia N9000 I really care about.
> >>
> >> AFAICT Meltdown is arm64 only?
> > 
> > IIRC ARMv7 is not affected by meltdown.
> > 
> >> Spectre affects the older boards, too, right? Was there any work done
> >> on that? cpuinfo says "ARMv7" for N900.
> > 
> > I remember that I saw some spectre patches for ARMv7 on LKML.

This is that patch series:
https://www.spinics.net/lists/arm-kernel/msg632065.html

> > In general for ARMv7 it is problematic as mitigation needs to change IBE
> 
> Not quite. IBE is part of ACTLR, which is an implementation defined
> register, so generalizing this statement to "ARMv7" is plain wrong. Case
> in point: A9, A12/A17 do not need any bit to be set. A8 needs IBE to
> allow BPIALL to work, A15 needs it for ICIALLUI to perform a BP
> invalidation.

Ok, Nokia N900 has Cortex A8.

-- 
Pali Rohár
pali.rohar@...il.com

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