From mboxrd@z Thu Jan 1 00:00:00 1970 From: jcm@jonmasters.org (Jon Masters) Date: Sat, 9 Jun 2018 08:53:08 -0400 Subject: [PATCH v2 05/17] arm64: Add 'ssbd' command-line option In-Reply-To: <20180529121121.24927-6-marc.zyngier@arm.com> References: <20180529121121.24927-1-marc.zyngier@arm.com> <20180529121121.24927-6-marc.zyngier@arm.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 05/29/2018 08:11 AM, Marc Zyngier wrote: > + ssbd= [ARM64,HW] > + Speculative Store Bypass Disable control > + > + On CPUs that are vulnerable to the Speculative > + Store Bypass vulnerability and offer a > + firmware based mitigation, this parameter > + indicates how the mitigation should be used: > + > + force-on: Unconditionally enable mitigation for > + for both kernel and userspace > + force-off: Unconditionally disable mitigation for > + for both kernel and userspace > + kernel: Always enable mitigation in the > + kernel, and offer a prctl interface > + to allow userspace to register its > + interest in being mitigated too. This should be "spec_store_bypass_disable" and it should have the same parameters as on x86: "on", "off", "auto". Why not just add "kernel"? (we had a "kernel" early on for x86 as well, and it might still end up coming back anyway). If there's a /compelling/ reason to have the Arm parameter differ, then it should still recognize the x86 parameter, similarly to how POWER also does that for cross-arch consistency. We'll add the x86 parameter way of doing it to RHEL anyway. Jon.