From: Michael Ellerman <mpe@ellerman.id.au>
To: "Michal Suchánek" <msuchanek@suse.de>
Cc: linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org, npiggin@gmail.com
Subject: Re: [PATCH 4/6] powerpc/64s: Enable barrier_nospec based on firmware settings
Date: Tue, 01 May 2018 21:11:06 +1000 [thread overview]
Message-ID: <87vac7r5px.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <20180426180258.04e6bee6@kitsune.suse.cz>
Michal Suchánek <msuchanek@suse.de> writes:
> Hello,
>
> On Tue, 24 Apr 2018 14:15:57 +1000
> Michael Ellerman <mpe@ellerman.id.au> wrote:
>
>> From: Michal Suchanek <msuchanek@suse.de>
>>
>> Check what firmware told us and enable/disable the barrier_nospec as
>> appropriate.
>>
>> We err on the side of enabling the barrier, as it's no-op on older
>> systems, see the comment for more detail.
>>
>> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
...
>
> I am missing the option for the barrier to be disabled by a kernel
> commandline argument here.
>
> It does make sense to add a kernel parameter that is checked on boot to
> be compatible with other platforms that implement one.
No other platforms have an option to disable variant 1 mitigations, so
there isn't an existing parameter we can use.
Which is not to say we can't add one, but I wasn't sure if it was really
worth it.
But I guess we should add one, I might do it as a follow-up patch.
cheers
next prev parent reply other threads:[~2018-05-01 11:11 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-24 4:15 [PATCH 1/6] powerpc/64s: Add barrier_nospec Michael Ellerman
2018-04-24 4:15 ` [PATCH 2/6] powerpc/64s: Add support for ori barrier_nospec patching Michael Ellerman
2018-04-26 16:10 ` Michal Suchánek
2018-05-01 12:25 ` Michael Ellerman
2018-04-24 4:15 ` [PATCH 3/6] powerpc/64s: Patch barrier_nospec in modules Michael Ellerman
2018-05-03 13:15 ` Michal Suchánek
2018-04-24 4:15 ` [PATCH 4/6] powerpc/64s: Enable barrier_nospec based on firmware settings Michael Ellerman
2018-04-26 16:02 ` Michal Suchánek
2018-05-01 11:11 ` Michael Ellerman [this message]
2018-05-02 11:41 ` Michal Suchánek
2018-05-04 0:58 ` Michael Ellerman
2018-04-24 4:15 ` [PATCH 5/6] powerpc: Use barrier_nospec in copy_from_user() Michael Ellerman
2018-04-24 4:15 ` [PATCH 6/6] powerpc/64: Use barrier_nospec in syscall entry Michael Ellerman
2018-04-24 5:44 ` [PATCH 1/6] powerpc/64s: Add barrier_nospec Nicholas Piggin
2018-05-28 13:19 ` [PATCH] powerpc/64s: Enhance the information in cpu_show_spectre_v1() Michal Suchanek
2018-05-29 14:03 ` kbuild test robot
2018-05-29 14:13 ` Christophe LEROY
2018-05-29 14:46 ` Michal Suchánek
2018-05-29 15:24 ` Christophe Leroy
2018-05-29 16:15 ` Joe Perches
2018-06-04 14:11 ` Michael Ellerman
2018-06-04 14:10 ` [1/6] powerpc/64s: Add barrier_nospec Michael Ellerman
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