From: Andre Przywara <andre.przywara@arm.com>
To: Jeremy Linton <jeremy.linton@arm.com>
Cc: stefan.wahren@i2se.com, mlangsdo@redhat.com,
suzuki.poulose@arm.com, marc.zyngier@arm.com,
catalin.marinas@arm.com, julien.thierry@arm.com,
will.deacon@arm.com, linux-kernel@vger.kernel.org,
steven.price@arm.com, shankerd@codeaurora.org, ykaukab@suse.de,
dave.martin@arm.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v4 09/12] arm64: Use firmware to detect CPUs that are not affected by Spectre-v2
Date: Thu, 31 Jan 2019 17:55:02 +0000 [thread overview]
Message-ID: <20190131175502.12bed0f0@donnerap.cambridge.arm.com> (raw)
In-Reply-To: <20190125180711.1970973-10-jeremy.linton@arm.com>
On Fri, 25 Jan 2019 12:07:08 -0600
Jeremy Linton <jeremy.linton@arm.com> wrote:
> From: Marc Zyngier <marc.zyngier@arm.com>
>
> The SMCCC ARCH_WORKAROUND_1 service can indicate that although the
> firmware knows about the Spectre-v2 mitigation, this particular
> CPU is not vulnerable, and it is thus not necessary to call
> the firmware on this CPU.
>
> Let's use this information to our benefit.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Yes, I stumbled over this in the firmware spec as well:
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Cheers,
Andre.
> ---
> arch/arm64/kernel/cpu_errata.c | 32 +++++++++++++++++++++++---------
> 1 file changed, 23 insertions(+), 9 deletions(-)
>
> diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
> index 4d23b4d4cfa8..024c83ffff99 100644
> --- a/arch/arm64/kernel/cpu_errata.c
> +++ b/arch/arm64/kernel/cpu_errata.c
> @@ -217,22 +217,36 @@ static int detect_harden_bp_fw(void)
> case PSCI_CONDUIT_HVC:
> arm_smccc_1_1_hvc(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
> ARM_SMCCC_ARCH_WORKAROUND_1, &res);
> - if ((int)res.a0 < 0)
> + switch ((int)res.a0) {
> + case 1:
> + /* Firmware says we're just fine */
> + return 0;
> + case 0:
> + cb = call_hvc_arch_workaround_1;
> + /* This is a guest, no need to patch KVM vectors */
> + smccc_start = NULL;
> + smccc_end = NULL;
> + break;
> + default:
> return -1;
> - cb = call_hvc_arch_workaround_1;
> - /* This is a guest, no need to patch KVM vectors */
> - smccc_start = NULL;
> - smccc_end = NULL;
> + }
> break;
>
> case PSCI_CONDUIT_SMC:
> arm_smccc_1_1_smc(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
> ARM_SMCCC_ARCH_WORKAROUND_1, &res);
> - if ((int)res.a0 < 0)
> + switch ((int)res.a0) {
> + case 1:
> + /* Firmware says we're just fine */
> + return 0;
> + case 0:
> + cb = call_smc_arch_workaround_1;
> + smccc_start = __smccc_workaround_1_smc_start;
> + smccc_end = __smccc_workaround_1_smc_end;
> + break;
> + default:
> return -1;
> - cb = call_smc_arch_workaround_1;
> - smccc_start = __smccc_workaround_1_smc_start;
> - smccc_end = __smccc_workaround_1_smc_end;
> + }
> break;
>
> default:
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next prev parent reply other threads:[~2019-01-31 17:55 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-25 18:06 [PATCH v4 00/12] arm64: add system vulnerability sysfs entries Jeremy Linton
2019-01-25 18:07 ` [PATCH v4 01/12] Documentation: Document arm64 kpti control Jeremy Linton
2019-01-30 18:02 ` Andre Przywara
2019-02-06 19:24 ` Jeremy Linton
2019-02-06 21:06 ` André Przywara
2019-01-31 17:58 ` Andre Przywara
2019-02-07 0:25 ` Jonathan Corbet
2019-01-25 18:07 ` [PATCH v4 02/12] arm64: Provide a command line to disable spectre_v2 mitigation Jeremy Linton
2019-01-30 18:03 ` Andre Przywara
2019-01-25 18:07 ` [PATCH v4 03/12] arm64: Remove the ability to build a kernel without ssbd Jeremy Linton
2019-01-30 18:04 ` Andre Przywara
2019-02-15 18:20 ` Catalin Marinas
2019-02-15 18:54 ` Jeremy Linton
2019-01-25 18:07 ` [PATCH v4 04/12] arm64: remove the ability to build a kernel without hardened branch predictors Jeremy Linton
2019-01-30 18:04 ` Andre Przywara
2019-01-25 18:07 ` [PATCH v4 05/12] arm64: remove the ability to build a kernel without kpti Jeremy Linton
2019-01-30 18:05 ` Andre Przywara
2019-01-25 18:07 ` [PATCH v4 06/12] arm64: add sysfs vulnerability show for spectre v1 Jeremy Linton
2019-01-31 17:52 ` Andre Przywara
2019-01-25 18:07 ` [PATCH v4 07/12] arm64: add sysfs vulnerability show for meltdown Jeremy Linton
2019-01-31 9:28 ` Julien Thierry
2019-01-31 21:48 ` Jeremy Linton
2019-01-31 17:54 ` Andre Przywara
2019-01-31 21:53 ` Jeremy Linton
2019-01-25 18:07 ` [PATCH v4 08/12] arm64: Advertise mitigation of Spectre-v2, or lack thereof Jeremy Linton
2019-01-31 17:54 ` Andre Przywara
2019-01-25 18:07 ` [PATCH v4 09/12] arm64: Use firmware to detect CPUs that are not affected by Spectre-v2 Jeremy Linton
2019-01-31 17:55 ` Andre Przywara [this message]
2019-01-25 18:07 ` [PATCH v4 10/12] arm64: add sysfs vulnerability show for spectre v2 Jeremy Linton
2019-01-31 17:55 ` Andre Przywara
2019-01-25 18:07 ` [PATCH v4 11/12] arm64: add sysfs vulnerability show for speculative store bypass Jeremy Linton
2019-01-31 17:55 ` Andre Przywara
2019-01-25 18:07 ` [PATCH v4 12/12] arm64: enable generic CPU vulnerabilites support Jeremy Linton
2019-01-31 17:56 ` Andre Przywara
2019-02-08 20:05 ` [PATCH v4 00/12] arm64: add system vulnerability sysfs entries Stefan Wahren
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