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=-9.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 C5581ECDE46 for ; Thu, 25 Oct 2018 14:19:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 83A262147A for ; Thu, 25 Oct 2018 14:19:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="D3P+Kthz" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 83A262147A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730310AbeJYWwB (ORCPT ); Thu, 25 Oct 2018 18:52:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:33828 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730290AbeJYWwA (ORCPT ); Thu, 25 Oct 2018 18:52:00 -0400 Received: from sasha-vm.mshome.net (unknown [167.98.65.38]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 76E2720834; Thu, 25 Oct 2018 14:19:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1540477143; bh=r9FnCF9sHqjrsaxJ/g4EVS1Ym7RknKTb5922kl9Mg00=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=D3P+Kthz+aidTd4Le490SJM79N7fDhgbDSKxDXJijvqKazWvAyYeWsGiM/96cKO+G sPH3zboUmmCCVro6zyFTrNMe6rh7K/gYGNkhDuGNK/PzYebS08uDYfRwfJRiugh4kf JSyNXAFDIgY3n7iLLUWc4ntWt3Ac13K7NviKpIMc= From: Sasha Levin To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Christian Borntraeger , Sasha Levin Subject: [PATCH AUTOSEL 3.18 03/98] s390/kvm: REPLACE barrier fixup with READ_ONCE Date: Thu, 25 Oct 2018 10:17:18 -0400 Message-Id: <20181025141853.214051-3-sashal@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181025141853.214051-1-sashal@kernel.org> References: <20181025141853.214051-1-sashal@kernel.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Christian Borntraeger [ Upstream commit 5de72a2247ac05bde7c89039631b3d0c6186fafb ] ACCESS_ONCE does not work reliably on non-scalar types. For example gcc 4.6 and 4.7 might remove the volatile tag for such accesses during the SRA (scalar replacement of aggregates) step (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145) Commit 1365039d0cb3 ("KVM: s390: Fix ipte locking") replace ACCESS_ONCE with barriers. Lets use READ_ONCE instead. Signed-off-by: Christian Borntraeger Acked-by: Paul E. McKenney Signed-off-by: Sasha Levin --- arch/s390/kvm/gaccess.c | 18 ++++++------------ 1 file changed, 6 insertions(+), 12 deletions(-) diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c index 6dc0ad9c7050..8f195fa904a1 100644 --- a/arch/s390/kvm/gaccess.c +++ b/arch/s390/kvm/gaccess.c @@ -229,12 +229,10 @@ static void ipte_lock_simple(struct kvm_vcpu *vcpu) goto out; ic = &vcpu->kvm->arch.sca->ipte_control; do { - old = *ic; - barrier(); + old = READ_ONCE(*ic); while (old.k) { cond_resched(); - old = *ic; - barrier(); + old = READ_ONCE(*ic); } new = old; new.k = 1; @@ -253,8 +251,7 @@ static void ipte_unlock_simple(struct kvm_vcpu *vcpu) goto out; ic = &vcpu->kvm->arch.sca->ipte_control; do { - old = *ic; - barrier(); + old = READ_ONCE(*ic); new = old; new.k = 0; } while (cmpxchg(&ic->val, old.val, new.val) != old.val); @@ -269,12 +266,10 @@ static void ipte_lock_siif(struct kvm_vcpu *vcpu) ic = &vcpu->kvm->arch.sca->ipte_control; do { - old = *ic; - barrier(); + old = READ_ONCE(*ic); while (old.kg) { cond_resched(); - old = *ic; - barrier(); + old = READ_ONCE(*ic); } new = old; new.k = 1; @@ -288,8 +283,7 @@ static void ipte_unlock_siif(struct kvm_vcpu *vcpu) ic = &vcpu->kvm->arch.sca->ipte_control; do { - old = *ic; - barrier(); + old = READ_ONCE(*ic); new = old; new.kh--; if (!new.kh) -- 2.17.1