From: Catalin Marinas <catalin.marinas@arm.com>
To: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: mlangsdo@redhat.com, linux-doc@vger.kernel.org,
julien.thierry@arm.com, marc.zyngier@arm.com,
andre.przywara@arm.com, corbet@lwn.net, will.deacon@arm.com,
linux-kernel@vger.kernel.org, jeremy.linton@arm.com,
stefan.wahren@i2e.com, linux-arm-kernel@lists.infradead.org,
dave.martin@arm.com, shankerd@codeaurora.org
Subject: Re: [PATCH v5 01/10] arm64: Provide a command line to disable spectre_v2 mitigation
Date: Thu, 28 Feb 2019 18:21:27 +0000 [thread overview]
Message-ID: <20190228182126.GA252518@arrakis.emea.arm.com> (raw)
In-Reply-To: <a0524741-e17a-a4b1-9d7c-3d001b2b581f@arm.com>
On Thu, Feb 28, 2019 at 06:14:34PM +0000, Suzuki K Poulose wrote:
> On 27/02/2019 01:05, Jeremy Linton wrote:
> > There are various reasons, including bencmarking, to disable spectrev2
> > mitigation on a machine. Provide a command-line to do so.
> >
> > Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
> > Cc: Jonathan Corbet <corbet@lwn.net>
> > Cc: linux-doc@vger.kernel.org
>
>
> > diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
> > index 9950bb0cbd52..d2b2c69d31bb 100644
> > --- a/arch/arm64/kernel/cpu_errata.c
> > +++ b/arch/arm64/kernel/cpu_errata.c
> > @@ -220,6 +220,14 @@ static void qcom_link_stack_sanitization(void)
> > : "=&r" (tmp));
> > }
> > +static bool __nospectre_v2;
> > +static int __init parse_nospectre_v2(char *str)
> > +{
> > + __nospectre_v2 = true;
> > + return 0;
> > +}
> > +early_param("nospectre_v2", parse_nospectre_v2);
> > +
> > static void
> > enable_smccc_arch_workaround_1(const struct arm64_cpu_capabilities *entry)
> > {
> > @@ -231,6 +239,11 @@ enable_smccc_arch_workaround_1(const struct arm64_cpu_capabilities *entry)
> > if (!entry->matches(entry, SCOPE_LOCAL_CPU))
> > return;
> > + if (__nospectre_v2) {
> > + pr_info_once("spectrev2 mitigation disabled by command line option\n");
> > + return;
> > + }
> > +
>
> Could we not disable the "cap" altogether instead, rather than disabling the
> work around ? Or do we need that information ?
There are a few ideas here but I think we settled on always reporting in
sysfs even if the mitigation is disabled in .config. So I guess we need
the "cap" around for the reporting part.
--
Catalin
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next prev parent reply other threads:[~2019-02-28 18:21 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-27 1:05 [PATCH v5 00/10] arm64: add system vulnerability sysfs entries Jeremy Linton
2019-02-27 1:05 ` [PATCH v5 01/10] arm64: Provide a command line to disable spectre_v2 mitigation Jeremy Linton
2019-02-28 18:14 ` Suzuki K Poulose
2019-02-28 18:21 ` Catalin Marinas [this message]
2019-02-28 18:25 ` Suzuki K Poulose
2019-03-01 6:54 ` Andre Przywara
2019-02-27 1:05 ` [PATCH v5 02/10] arm64: add sysfs vulnerability show for spectre v1 Jeremy Linton
2019-02-28 18:29 ` Suzuki K Poulose
2019-03-01 6:54 ` Andre Przywara
2019-02-27 1:05 ` [PATCH v5 03/10] arm64: add sysfs vulnerability show for meltdown Jeremy Linton
2019-02-28 18:33 ` Suzuki K Poulose
2019-03-01 7:11 ` Andre Przywara
2019-03-01 16:12 ` Jeremy Linton
2019-03-01 16:20 ` Catalin Marinas
2019-03-01 16:53 ` Jeremy Linton
2019-03-01 17:15 ` Catalin Marinas
2019-03-01 17:30 ` Andre Przywara
2019-02-27 1:05 ` [PATCH v5 04/10] arm64: Advertise mitigation of Spectre-v2, or lack thereof Jeremy Linton
2019-03-01 6:57 ` Andre Przywara
2019-02-27 1:05 ` [PATCH v5 05/10] arm64: Use firmware to detect CPUs that are not affected by Spectre-v2 Jeremy Linton
2019-03-01 6:58 ` Andre Przywara
2019-02-27 1:05 ` [PATCH v5 06/10] arm64: Always enable spectrev2 vulnerability detection Jeremy Linton
2019-03-01 6:58 ` Andre Przywara
2019-02-27 1:05 ` [PATCH v5 07/10] arm64: add sysfs vulnerability show for spectre v2 Jeremy Linton
2019-03-01 6:59 ` Andre Przywara
2019-02-27 1:05 ` [PATCH v5 08/10] arm64: Always enable ssb vulnerability detection Jeremy Linton
2019-03-01 7:02 ` Andre Przywara
2019-03-01 16:16 ` Jeremy Linton
2019-02-27 1:05 ` [PATCH v5 09/10] arm64: add sysfs vulnerability show for speculative store bypass Jeremy Linton
2019-03-01 7:02 ` Andre Przywara
2019-03-01 16:41 ` Jeremy Linton
2019-02-27 1:05 ` [PATCH v5 10/10] arm64: enable generic CPU vulnerabilites support Jeremy Linton
2019-03-01 7:03 ` Andre Przywara
2019-02-28 12:01 ` [PATCH v5 00/10] arm64: add system vulnerability sysfs entries Catalin Marinas
2019-03-01 19:35 ` Stefan Wahren
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