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

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Date:   Fri, 2 Mar 2018 17:02:32 +0800
From:   Alex Shi <alex.shi@...aro.org>
To:     Greg KH <greg@...ah.com>
Cc:     Marc Zyngier <marc.zyngier@....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 03/02/2018 12:46 AM, Greg KH wrote:
> On Thu, Mar 01, 2018 at 08:53:37PM +0800, Alex Shi wrote:
>> Hi All,
>>
>> 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
> 
> Also, how did you test, what platforms did you test, and did you test
> that this actually did fix the spectre issue on your platforms?  If so,
> what test did you use?
> 

On the kernelci, there are 18 kinds of platoforms with different
configure tested booting, detailed info is here:
https://kernelci.org/boot/all/job/lsk/branch/linux-linaro-lsk-v4.9-test/kernel/lsk-v4.9-17.03-4844-g6f782cff6edb/

I also tested the qemu boot on hikey620. and normal boot on
hikey620/db410c/junor2. The other testing include the LKFT testing which
is reported by email, same as test for LTS. None of testing show
regressions.

As testing the spectre bug fix, that's a good question. I also asked
this question to original patch authors, like Marc. They said they just
figure out these patches could block spectre or meltdown issue. From my
side, I just reproduced the process internal spectre. But all fix on arm
can not resolve the user space internal spectre. It can block from user
to kernel or kernel to user spectre according the code purose. So I
believe these patch could do their job. And arm cpu would drop the
spectre branches if it has 20+ 'nop' instructions...

Regards
Alex