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=-9.8 required=3.0 tests=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 20D33C73C41 for ; Tue, 9 Jul 2019 12:25:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EC7A8216E3 for ; Tue, 9 Jul 2019 12:25:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726523AbfGIMZX (ORCPT ); Tue, 9 Jul 2019 08:25:23 -0400 Received: from foss.arm.com ([217.140.110.172]:42644 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726025AbfGIMZW (ORCPT ); Tue, 9 Jul 2019 08:25:22 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 2A4B7344; Tue, 9 Jul 2019 05:25:22 -0700 (PDT) Received: from filthy-habits.cambridge.arm.com (unknown [10.1.197.61]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5E0143F59C; Tue, 9 Jul 2019 05:25:20 -0700 (PDT) From: Marc Zyngier To: Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= Cc: Andre Przywara , Andrew Murray , Dave Martin , Eric Auger , James Morse , Julien Thierry , Steven Price , Sudeep Holla , Suzuki K Poulose , kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH 01/18] arm64: assembler: Switch ESB-instruction with a vanilla nop if !ARM64_HAS_RAS Date: Tue, 9 Jul 2019 13:24:50 +0100 Message-Id: <20190709122507.214494-2-marc.zyngier@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190709122507.214494-1-marc.zyngier@arm.com> References: <20190709122507.214494-1-marc.zyngier@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: James Morse The ESB-instruction is a nop on CPUs that don't implement the RAS extensions. This lets us use it in places like the vectors without having to use alternatives. If someone disables CONFIG_ARM64_RAS_EXTN, this instruction still has its RAS extensions behaviour, but we no longer read DISR_EL1 as this register does depend on alternatives. This could go wrong if we want to synchronize an SError from a KVM guest. On a CPU that has the RAS extensions, but the KConfig option was disabled, we consume the pending SError with no chance of ever reading it. Hide the ESB-instruction behind the CONFIG_ARM64_RAS_EXTN option, outputting a regular nop if the feature has been disabled. Reported-by: Julien Thierry Signed-off-by: James Morse Signed-off-by: Marc Zyngier --- arch/arm64/include/asm/assembler.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h index 570d195a184d..e3a15c751b13 100644 --- a/arch/arm64/include/asm/assembler.h +++ b/arch/arm64/include/asm/assembler.h @@ -96,7 +96,11 @@ * RAS Error Synchronization barrier */ .macro esb +#ifdef CONFIG_ARM64_RAS_EXTN hint #16 +#else + nop +#endif .endm /* -- 2.20.1