From: Suzuki K Poulose <suzuki.poulose@arm.com>
To: jeremy.linton@arm.com, linux-arm-kernel@lists.infradead.org
Cc: mlangsdo@redhat.com, linux-doc@vger.kernel.org,
julien.thierry@arm.com, marc.zyngier@arm.com,
catalin.marinas@arm.com, corbet@lwn.net, will.deacon@arm.com,
linux-kernel@vger.kernel.org, stefan.wahren@i2e.com,
andre.przywara@arm.com, 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 18:14:34 +0000 [thread overview]
Message-ID: <a0524741-e17a-a4b1-9d7c-3d001b2b581f@arm.com> (raw)
In-Reply-To: <20190227010544.597579-2-jeremy.linton@arm.com>
Hi Jeremy
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 ?
Cheers
Suzuki
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next prev parent reply other threads:[~2019-02-28 18:14 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 [this message]
2019-02-28 18:21 ` Catalin Marinas
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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