From: Greg KH <greg@kroah.com>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Alex Shi <alex.shi@linaro.org>,
Marc Zyngier <marc.zyngier@arm.com>,
Will Deacon <will.deacon@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
stable@vger.kernel.org,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/29] arm meltdown fix backporting review for lts 4.9
Date: Tue, 13 Mar 2018 14:25:10 +0100 [thread overview]
Message-ID: <20180313132510.GA3629@kroah.com> (raw)
In-Reply-To: <CAKv+Gu8ratRYnGzNm5qppUetEFt4Dief_3_Dj6yaW==DJemeHQ@mail.gmail.com>
On Tue, Mar 13, 2018 at 01:01:43PM +0000, Ard Biesheuvel wrote:
> On 13 March 2018 at 10:38, Greg KH <greg@kroah.com> wrote:
> > On Tue, Mar 13, 2018 at 10:13:26AM +0000, Ard Biesheuvel wrote:
> >> On 13 March 2018 at 10:04, Greg KH <greg@kroah.com> wrote:
> >> > On Wed, Mar 07, 2018 at 06:24:09PM +0000, Ard Biesheuvel wrote:
> >> >> On 2 March 2018 at 16:54, Greg KH <greg@kroah.com> wrote:
> ...
> >> >> > Please test on the hardware that is affected, otherwise you do not know
> >> >> > if your patches do anything or not.
> >> >> >
> >> >>
> >> >> I don't think it is feasible to test these backports by confirming
> >> >> that they make the fundamental issue go away. We simply don't have the
> >> >> code to reproduce all the variants, and we have to rely on the
> >> >> information provided by ARM Ltd. regarding which cores are affected
> >> >> and which aren't.
> >> >
> >> > You really don't have the reproducers? Please work with ARM to resolve
> >> > that, this should not be a non-tested set of patches. That's really
> >> > worse than no patches at all, as if they were applied, that would
> >> > provide a false-sense of "all is fixed".
> >> >
> >>
> >> I know that on x86, the line between architecture and platform is
> >> blurry. That is not the case on ARM, though.
> >>
> >> Unlike platform firmware, the OS is built on top of an abstracted
> >> platform which is described by ARM's Architecture Reference Manual. If
> >> ARM Ltd. issues recommendations regarding what firmware PSCI methods
> >> to call when doing a context switch, or which barrier instruction to
> >> issue in certain circumstances, they do so because a certain class of
> >> hardware may require it in some cases. It is really not up to me to go
> >> find some exploit code on GitHub, run it before and after applying the
> >> patch and conclude that the problem is fixed. Instead, what I should
> >> do is confirm that the changes result in the recommended actions to be
> >> taken at the appropriate times.
> >
> > To _not_ take that exploit code and run it to _verify_ that your patches
> > work, would be foolish, right?
> >
>
> Oh, absolutely. But that presupposes access to both the affected
> hardware and the exploit code.
If you all don't have access to both, then someone is doing something
seriously wrong. Go complain to ARM please, we all know they have both.
I just got done yelling at a whole bunch of vendors last week about this
whole mess at a very large meeting of a lot of different Linux-based
companies. It's crazy that the disfunction is still happening.
greg k-h
prev parent reply other threads:[~2018-03-13 13:25 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-28 3:56 [PATCH 0/29] arm meltdown fix backporting review for lts 4.9 Alex Shi
2018-02-28 3:56 ` [PATCH 01/29] arm64: mm: Use non-global mappings for kernel space Alex Shi
2018-02-28 12:08 ` Greg KH
2018-03-01 11:53 ` Alex Shi
2018-02-28 3:56 ` [PATCH 02/29] arm64: mm: Move ASID from TTBR0 to TTBR1 Alex Shi
2018-02-28 3:56 ` [PATCH 03/29] arm64: mm: Allocate ASIDs in pairs Alex Shi
2018-02-28 3:56 ` [PATCH 04/29] arm64: mm: Add arm64_kernel_unmapped_at_el0 helper Alex Shi
2018-02-28 3:56 ` [PATCH 05/29] arm64: mm: Invalidate both kernel and user ASIDs when performing TLBI Alex Shi
2018-02-28 3:56 ` [PATCH 06/29] arm64: factor out entry stack manipulation Alex Shi
2018-02-28 3:56 ` [PATCH 07/29] arm64: entry.S: move SError handling into a C function for future expansion Alex Shi
2018-02-28 3:56 ` [PATCH 08/29] module: extend 'rodata=off' boot cmdline parameter to module mappings Alex Shi
2018-02-28 3:56 ` [PATCH 09/29] arm64: entry: Add exception trampoline page for exceptions from EL0 Alex Shi
2018-02-28 3:56 ` [PATCH 10/29] arm64: mm: Map entry trampoline into trampoline and kernel page tables Alex Shi
2018-02-28 3:56 ` [PATCH 11/29] arm64: entry: Explicitly pass exception level to kernel_ventry macro Alex Shi
2018-02-28 3:56 ` [PATCH 12/29] arm64: entry: Hook up entry trampoline to exception vectors Alex Shi
2018-02-28 3:56 ` [PATCH 13/29] arm64: tls: Avoid unconditional zeroing of tpidrro_el0 for native tasks Alex Shi
2018-02-28 3:56 ` [PATCH 14/29] arm64: entry: Add fake CPU feature for unmapping the kernel at EL0 Alex Shi
2018-02-28 3:56 ` [PATCH 15/29] arm64: kaslr: Put kernel vectors address in separate data page Alex Shi
2018-02-28 3:56 ` [PATCH 16/29] arm64: use RET instruction for exiting the trampoline Alex Shi
2018-02-28 3:56 ` [PATCH 17/29] arm64: Kconfig: Add CONFIG_UNMAP_KERNEL_AT_EL0 Alex Shi
2018-02-28 3:56 ` [PATCH 18/29] arm64: Kconfig: Reword UNMAP_KERNEL_AT_EL0 kconfig entry Alex Shi
2018-02-28 3:56 ` [PATCH 19/29] arm64: Take into account ID_AA64PFR0_EL1.CSV3 Alex Shi
2018-02-28 3:56 ` [PATCH 20/29] arm64: Allow checking of a CPU-local erratum Alex Shi
2018-02-28 3:56 ` [PATCH 21/29] arm64: capabilities: Handle duplicate entries for a capability Alex Shi
2018-02-28 3:56 ` [PATCH 22/29] arm64: cputype: Add missing MIDR values for Cortex-A72 and Cortex-A75 Alex Shi
2018-02-28 3:56 ` [PATCH 23/29] arm64: cputype: Add MIDR values for Cavium ThunderX2 CPUs Alex Shi
2018-02-28 3:56 ` [PATCH 24/29] arm64: Turn on KPTI only on CPUs that need it Alex Shi
2018-02-28 3:56 ` [PATCH 25/29] arm64: kpti: Make use of nG dependent on arm64_kernel_unmapped_at_el0() Alex Shi
2018-02-28 3:56 ` [PATCH 26/29] arm64: kpti: Add ->enable callback to remap swapper using nG mappings Alex Shi
2018-02-28 3:56 ` [PATCH 27/29] arm64: Force KPTI to be disabled on Cavium ThunderX Alex Shi
2018-02-28 3:56 ` [PATCH 28/29] arm64: entry: Reword comment about post_ttbr_update_workaround Alex Shi
2018-02-28 3:56 ` [PATCH 29/29] arm64: idmap: Use "awx" flags for .idmap.text .pushsection directives Alex Shi
2018-02-28 4:02 ` [PATCH 0/29] arm meltdown fix backporting review for lts 4.9 Alex Shi
2018-03-01 15:24 ` Greg KH
2018-03-02 9:14 ` Alex Shi
2018-03-02 10:32 ` Marc Zyngier
2018-03-02 16:54 ` Greg KH
2018-03-05 12:46 ` Mark Brown
2018-03-05 13:08 ` Greg KH
2018-03-06 14:26 ` Mark Brown
2018-03-06 17:25 ` Greg KH
2018-03-06 21:31 ` Mark Brown
2018-03-13 10:03 ` Greg KH
2018-03-07 4:43 ` Alex Shi
2018-03-07 3:27 ` Alex Shi
2018-03-07 18:24 ` Ard Biesheuvel
2018-03-13 10:04 ` Greg KH
2018-03-13 10:13 ` Ard Biesheuvel
2018-03-13 10:38 ` Greg KH
2018-03-13 13:01 ` Ard Biesheuvel
2018-03-13 13:25 ` Greg KH [this message]
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