From: Jon Masters <jcm@jonmasters.org>
To: Marc Zyngier <marc.zyngier@arm.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu
Cc: Will Deacon <will.deacon@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Andy Lutomirski <luto@kernel.org>,
Kees Cook <keescook@chromium.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Christoffer Dall <christoffer.dall@arm.com>,
Randy Dunlap <rdunlap@infradead.org>,
Dominik Brodowski <linux@dominikbrodowski.net>,
Julien Grall <julien.grall@arm.com>,
Mark Rutland <mark.rutland@arm.com>
Subject: Re: [PATCH v2 00/17] arm64 SSBD (aka Spectre-v4) mitigation
Date: Sat, 9 Jun 2018 09:16:03 -0400 [thread overview]
Message-ID: <3f90aca2-d693-5f3e-4f2b-51e9509af8fe@jonmasters.org> (raw)
In-Reply-To: <20180529121121.24927-1-marc.zyngier@arm.com>
On 05/29/2018 08:11 AM, Marc Zyngier wrote:
> This patch series implements the Linux kernel side of the "Spectre-v4"
> (CVE-2018-3639) mitigation known as "Speculative Store Bypass Disable"
> (SSBD).
Looks good, with the exception of the naming in patch 5, and a question
about how you're handling live migration of VMs (which needs to preserve
mitigation state). Once those are answered I think it's good.
> For all released Arm Cortex-A CPUs that are affected by this issue, then
> the preferred mitigation is simply to set a chicken bit in the firmware
> during CPU initialisation and therefore no change to Linux is required.
> Other CPUs may require the chicken bit to be toggled dynamically (for
> example, when switching between user-mode and kernel-mode) and this is
> achieved by calling into EL3 via an SMC which has been published as part
> of the latest SMCCC specification:
We're asking (server) silicon vendors that can do so inexpensively to
implement both a firmware knob to control the chicken bit and the ATF
interface. This allows some users to disable the mitigation if they want
to, for example in closed lab environments doing CONFIG_BENCHMARKING
comparisons to other arches which might have mitigations disabled. Not
that I like that, but I want Arm to be on an equal footing at least ;)
Jon.
prev parent reply other threads:[~2018-06-09 13:17 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-29 12:11 [PATCH v2 00/17] arm64 SSBD (aka Spectre-v4) mitigation Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 01/17] arm/arm64: smccc: Add SMCCC-specific return codes Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 02/17] arm64: Call ARCH_WORKAROUND_2 on transitions between EL0 and EL1 Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 03/17] arm64: Add per-cpu infrastructure to call ARCH_WORKAROUND_2 Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 04/17] arm64: Add ARCH_WORKAROUND_2 probing Marc Zyngier
2018-05-29 13:39 ` Suzuki K Poulose
2018-05-29 12:11 ` [PATCH v2 05/17] arm64: Add 'ssbd' command-line option Marc Zyngier
2018-06-09 12:53 ` Jon Masters
2018-06-09 13:19 ` Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 06/17] arm64: ssbd: Add global mitigation state accessor Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 07/17] arm64: ssbd: Skip apply_ssbd if not using dynamic mitigation Marc Zyngier
2018-06-09 13:03 ` Jon Masters
2018-06-09 13:21 ` Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 08/17] arm64: ssbd: Restore mitigation status on CPU resume Marc Zyngier
2018-05-29 13:35 ` Mark Rutland
2018-05-29 12:11 ` [PATCH v2 09/17] arm64: ssbd: Introduce thread flag to control userspace mitigation Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 10/17] arm64: ssbd: Add prctl interface for per-thread mitigation Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 11/17] arm64: KVM: Add HYP per-cpu accessors Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 12/17] arm64: KVM: Add ARCH_WORKAROUND_2 support for guests Marc Zyngier
2018-06-09 13:09 ` Jon Masters
2018-06-09 13:21 ` Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 13/17] arm64: KVM: Handle guest's ARCH_WORKAROUND_2 requests Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 14/17] arm64: KVM: Add ARCH_WORKAROUND_2 discovery through ARCH_FEATURES_FUNC_ID Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 15/17] arm64: Add test_and_clear_flag and set_flag atomic assembler primitives Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 16/17] arm64: ssbd: Enable delayed setting of TIF_SSBD Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 17/17] arm64: ssbd: Implement arch_seccomp_spec_mitigate Marc Zyngier
2018-05-30 15:58 ` [PATCH v2 00/17] arm64 SSBD (aka Spectre-v4) mitigation Will Deacon
2018-05-31 16:41 ` Catalin Marinas
2018-05-31 16:55 ` Marc Zyngier
2018-06-09 13:16 ` Jon Masters [this message]
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