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

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Date:   Fri, 02 Mar 2018 10:29:56 +0000
From:   Marc Zyngier <marc.zyngier@....com>
To:     Alex Shi <alex.shi@...aro.org>
Cc:     Greg KH <greg@...ah.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 Fri, 02 Mar 2018 09:02:32 +0000,
Alex Shi wrote:
> 
> 
> 
> 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

Did you try QEMU in conjunction with KVM? Or just in emulation?

> 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...

What are you talking about? What's that story about NOPs? There are
clear mitigation guidelines for ARM cores, please don't make things
up.

	M.

-- 
Jazz is not dead, it just smell funny.