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

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Date:   Thu, 8 Mar 2018 13:35:49 +0000
From:   Marc Zyngier <marc.zyngier@....com>
To:     Pali Rohár <pali.rohar@...il.com>,
        Pavel Machek <pavel@....cz>
Cc:     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 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.
> 
> 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.

	M.
-- 
Jazz is not dead. It just smells funny...