From patchwork Tue Nov 3 20:37:42 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 316939 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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 9FA02C388F9 for ; Tue, 3 Nov 2020 21:27:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6969F20757 for ; Tue, 3 Nov 2020 21:27:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604438839; bh=l8T1BxpdWMGORtkMch0zBnZHthm9bcp8z4QUo4Yj+JU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=rLOw7k1EbL9xPaHkN3ElfyhUBroLXXHxDkB8tu759d7k5huIvUlupp66vACqaMQ91 OMvY3Y52l18c+suCrlW/BrjqqJUhNPecQmrTIS574ConHIULKtYO7TNqWjXYesjWjG 5G68sNSHTZqH3AAFN+qkJEIWZU6li8LiqEtqBIPA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732548AbgKCVBB (ORCPT ); Tue, 3 Nov 2020 16:01:01 -0500 Received: from mail.kernel.org ([198.145.29.99]:37176 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733294AbgKCVBA (ORCPT ); Tue, 3 Nov 2020 16:01:00 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D1F8321534; Tue, 3 Nov 2020 21:00:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604437259; bh=l8T1BxpdWMGORtkMch0zBnZHthm9bcp8z4QUo4Yj+JU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0J/ccn2M+gwHxMebd1g851iCiBOscm04EfsmPCZPMNC2iU88GT2uTFe7WjHqiXJwr u1gYlhErJ38dTrtlSLCc3K4PnsKEDJwsKQxcwskm54DJGgPjsjjW1c+itwySHypEoR GxVf8yuo8DvXCXB8jG5bn1zYR99LG9Hxsw/eUIC4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Stephen Boyd , Marc Zyngier , Will Deacon , Andre Przywara , Steven Price Subject: [PATCH 5.4 214/214] KVM: arm64: ARM_SMCCC_ARCH_WORKAROUND_1 doesnt return SMCCC_RET_NOT_REQUIRED Date: Tue, 3 Nov 2020 21:37:42 +0100 Message-Id: <20201103203310.638169023@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201103203249.448706377@linuxfoundation.org> References: <20201103203249.448706377@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Stephen Boyd commit 1de111b51b829bcf01d2e57971f8fd07a665fa3f upstream. 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 Fixes: c118bbb52743 ("arm64: KVM: Propagate full Spectre v2 workaround state to KVM guests") Signed-off-by: Stephen Boyd Acked-by: Marc Zyngier Acked-by: Will Deacon Cc: Andre Przywara Cc: Steven Price Cc: Marc Zyngier Cc: stable@vger.kernel.org Link: https://developer.arm.com/documentation/den0028/latest [1] Link: https://lore.kernel.org/r/20201023154751.1973872-1-swboyd@chromium.org Signed-off-by: Will Deacon Signed-off-by: Stephen Boyd Signed-off-by: Greg Kroah-Hartman --- include/linux/arm-smccc.h | 2 ++ virt/kvm/arm/psci.c | 2 +- 2 files changed, 3 insertions(+), 1 deletion(-) --- a/include/linux/arm-smccc.h +++ b/include/linux/arm-smccc.h @@ -76,6 +76,8 @@ ARM_SMCCC_SMC_32, \ 0, 0x7fff) +#define SMCCC_ARCH_WORKAROUND_RET_UNAFFECTED 1 + #ifndef __ASSEMBLY__ #include --- a/virt/kvm/arm/psci.c +++ b/virt/kvm/arm/psci.c @@ -408,7 +408,7 @@ int kvm_hvc_call_handler(struct kvm_vcpu val = SMCCC_RET_SUCCESS; break; case KVM_BP_HARDEN_NOT_REQUIRED: - val = SMCCC_RET_NOT_REQUIRED; + val = SMCCC_ARCH_WORKAROUND_RET_UNAFFECTED; break; } break;