From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E6A54C43381 for ; Fri, 1 Mar 2019 06:58:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BE4552084F for ; Fri, 1 Mar 2019 06:58:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729242AbfCAG6X (ORCPT ); Fri, 1 Mar 2019 01:58:23 -0500 Received: from foss.arm.com ([217.140.101.70]:58620 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726025AbfCAG6X (ORCPT ); Fri, 1 Mar 2019 01:58:23 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id DEF36EBD; Thu, 28 Feb 2019 22:58:22 -0800 (PST) Received: from [172.20.0.134] (usa-sjc-mx-foss1.foss.arm.com [217.140.101.70]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0D7653F5C1; Thu, 28 Feb 2019 22:58:21 -0800 (PST) Subject: Re: [PATCH v5 05/10] arm64: Use firmware to detect CPUs that are not affected by Spectre-v2 To: Jeremy Linton , linux-arm-kernel@lists.infradead.org Cc: catalin.marinas@arm.com, will.deacon@arm.com, marc.zyngier@arm.com, suzuki.poulose@arm.com, Dave.Martin@arm.com, shankerd@codeaurora.org, julien.thierry@arm.com, mlangsdo@redhat.com, stefan.wahren@i2e.com, linux-kernel@vger.kernel.org References: <20190227010544.597579-1-jeremy.linton@arm.com> <20190227010544.597579-6-jeremy.linton@arm.com> From: Andre Przywara Message-ID: Date: Fri, 1 Mar 2019 00:58:19 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <20190227010544.597579-6-jeremy.linton@arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 2/26/19 7:05 PM, Jeremy Linton wrote: > From: Marc Zyngier > > 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. Yes, that matches the firmware interface description. > Signed-off-by: Marc Zyngier > Signed-off-by: Jeremy Linton Reviewed-by: Andre Przywara 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 c8972255b365..77f021e78a28 100644 > --- a/arch/arm64/kernel/cpu_errata.c > +++ b/arch/arm64/kernel/cpu_errata.c > @@ -230,22 +230,36 @@ 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: >