From patchwork Fri Oct 23 15:47:50 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stephen Boyd X-Patchwork-Id: 290230 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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT 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 8366CC4363A for ; Fri, 23 Oct 2020 15:47:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 241FC21D47 for ; Fri, 23 Oct 2020 15:47:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="M/GS969E" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S463306AbgJWPry (ORCPT ); Fri, 23 Oct 2020 11:47:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41762 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S463578AbgJWPry (ORCPT ); Fri, 23 Oct 2020 11:47:54 -0400 Received: from mail-pf1-x444.google.com (mail-pf1-x444.google.com [IPv6:2607:f8b0:4864:20::444]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B3A45C0613CE for ; Fri, 23 Oct 2020 08:47:53 -0700 (PDT) Received: by mail-pf1-x444.google.com with SMTP id a200so1631799pfa.10 for ; Fri, 23 Oct 2020 08:47:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=Euid2rOIqVxU7BCKc29LGBrOY7GyDm6FtEEpwHglGRU=; b=M/GS969E9V3i09GCuC41mYN/VDUOQUKzlMSMBpISUGxrl8e0AnBOu62xTbAgpXkzbS 5NLXBjzluFLSNZyvQWzcBuXc9alqLSImvHEoFLme/j0k89U1z+qsRc2m0IB+PsXamJf5 k1wezWUJ+yz+ead4BL9mEB0rQpouYI/1056Hk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=Euid2rOIqVxU7BCKc29LGBrOY7GyDm6FtEEpwHglGRU=; b=HRJGuL2ZM1liBD9drasdBPdpTLiZS3zlZAlNSmas81STRP6jf8oqeJrFhbPUt9X+Kk CDMfK/msZKCfJs25nje97U662/13YQp/bp+Z3MUke06mpKDIt2ldfMSAjSsGtiKqXu5g tlhmAM5y/sYY53MM+7T00xpson8z/+MF0dUnlzE+pJKdkpd6XMfHISyzDTCKwVC46+Fe oxluMAtKC2bkxvaHRhJOWGAy3uzrZaWwpqghqBxBtee2ZeIIecMoJVaPwsAS4kJ/O3Mf tuA6Ba2C4qU+MR+EvdeJ08W4hcDaSTXJTTg843cmNF9bclWhMwYg+IqWoDDq9GMiT6tA kHLQ== X-Gm-Message-State: AOAM531I3VF9/DHc/uPS/MaiZj5bvu8v1eJ77XE7/5lWHRlKOV+utAsA jsFDdD2/lXRNtg1TyOJePlsRpw== X-Google-Smtp-Source: ABdhPJzYLUg/ViEmI70rBqC4Esx7lIduLkcNso4qinU5LfKpUejh1bMzhBnu8IwRnHgAqpvsWGhV+A== X-Received: by 2002:a62:7cd4:0:b029:154:f9ee:320b with SMTP id x203-20020a627cd40000b0290154f9ee320bmr2955753pfc.26.1603468073137; Fri, 23 Oct 2020 08:47:53 -0700 (PDT) Received: from smtp.gmail.com ([2620:15c:202:201:3e52:82ff:fe6c:83ab]) by smtp.gmail.com with ESMTPSA id t6sm2532576pfl.50.2020.10.23.08.47.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 23 Oct 2020 08:47:52 -0700 (PDT) From: Stephen Boyd To: Will Deacon , Catalin Marinas Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Andre Przywara , Steven Price , Marc Zyngier , stable@vger.kernel.org Subject: [PATCH v3] KVM: arm64: ARM_SMCCC_ARCH_WORKAROUND_1 doesn't return SMCCC_RET_NOT_REQUIRED Date: Fri, 23 Oct 2020 08:47:50 -0700 Message-Id: <20201023154751.1973872-1-swboyd@chromium.org> X-Mailer: git-send-email 2.29.0.rc1.297.gfa9743e501-goog MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org According to the SMCCC spec[1](7.5.2 Discovery) the ARM_SMCCC_ARCH_WORKAROUND_1 function id only returns 0, 1, and SMCCC_RET_NOT_SUPPORTED. 0 is "workaround required and safe to call this function" 1 is "workaround not required but safe to call this function" SMCCC_RET_NOT_SUPPORTED is "might be vulnerable or might not be, who knows, I give up!" SMCCC_RET_NOT_SUPPORTED might as well mean "workaround required, except calling this function may not work because it isn't implemented in some cases". Wonderful. We map this SMC call to 0 is SPECTRE_MITIGATED 1 is SPECTRE_UNAFFECTED SMCCC_RET_NOT_SUPPORTED is SPECTRE_VULNERABLE For KVM hypercalls (hvc), we've implemented this function id to return SMCCC_RET_NOT_SUPPORTED, 0, and SMCCC_RET_NOT_REQUIRED. One of those isn't supposed to be there. Per the code we call arm64_get_spectre_v2_state() to figure out what to return for this feature discovery call. 0 is SPECTRE_MITIGATED SMCCC_RET_NOT_REQUIRED is SPECTRE_UNAFFECTED SMCCC_RET_NOT_SUPPORTED is SPECTRE_VULNERABLE Let's clean this up so that KVM tells the guest this mapping: 0 is SPECTRE_MITIGATED 1 is SPECTRE_UNAFFECTED SMCCC_RET_NOT_SUPPORTED is SPECTRE_VULNERABLE Note: SMCCC_RET_NOT_AFFECTED is 1 but isn't part of the SMCCC spec Cc: Andre Przywara Cc: Steven Price Cc: Marc Zyngier Cc: stable@vger.kernel.org Link: https://developer.arm.com/documentation/den0028/latest [1] Fixes: c118bbb52743 ("arm64: KVM: Propagate full Spectre v2 workaround state to KVM guests") Signed-off-by: Stephen Boyd Acked-by: Will Deacon Acked-by: Marc Zyngier --- I see that before commit c118bbb52743 ("arm64: KVM: Propagate full Spectre v2 workaround state to KVM guests") we had this mapping: 0 is SPECTRE_MITIGATED SMCCC_RET_NOT_SUPPORTED is SPECTRE_VULNERABLE so the return value '1' wasn't there then. Once the commit was merged we introduced the notion of NOT_REQUIRED here when it shouldn't have been introduced. Changes from v2: * Moved define to header file and used it Changes from v1: * Way longer commit text, more background (sorry) * Dropped proton-pack part because it was wrong * Rebased onto other patch accepted upstream arch/arm64/kernel/proton-pack.c | 2 -- arch/arm64/kvm/hypercalls.c | 2 +- include/linux/arm-smccc.h | 2 ++ 3 files changed, 3 insertions(+), 3 deletions(-) base-commit: 66dd3474702aa98d5844367e1577cdad78ef7c65 diff --git a/arch/arm64/kernel/proton-pack.c b/arch/arm64/kernel/proton-pack.c index 25f3c80b5ffe..c18eb7d41274 100644 --- a/arch/arm64/kernel/proton-pack.c +++ b/arch/arm64/kernel/proton-pack.c @@ -135,8 +135,6 @@ static enum mitigation_state spectre_v2_get_cpu_hw_mitigation_state(void) return SPECTRE_VULNERABLE; } -#define SMCCC_ARCH_WORKAROUND_RET_UNAFFECTED (1) - static enum mitigation_state spectre_v2_get_cpu_fw_mitigation_state(void) { int ret; diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c index 9824025ccc5c..25ea4ecb6449 100644 --- a/arch/arm64/kvm/hypercalls.c +++ b/arch/arm64/kvm/hypercalls.c @@ -31,7 +31,7 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu) val = SMCCC_RET_SUCCESS; break; case SPECTRE_UNAFFECTED: - val = SMCCC_RET_NOT_REQUIRED; + val = SMCCC_ARCH_WORKAROUND_RET_UNAFFECTED; break; } break; diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h index 15c706fb0a37..0e50ba3e88d7 100644 --- a/include/linux/arm-smccc.h +++ b/include/linux/arm-smccc.h @@ -86,6 +86,8 @@ ARM_SMCCC_SMC_32, \ 0, 0x7fff) +#define SMCCC_ARCH_WORKAROUND_RET_UNAFFECTED 1 + /* Paravirtualised time calls (defined by ARM DEN0057A) */ #define ARM_SMCCC_HV_PV_TIME_FEATURES \ ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \