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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 7D44FC28CF6 for ; Wed, 1 Aug 2018 17:25:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 241D020844 for ; Wed, 1 Aug 2018 17:25:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 241D020844 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.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 S2406856AbeHATMU (ORCPT ); Wed, 1 Aug 2018 15:12:20 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:51374 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389883AbeHATMS (ORCPT ); Wed, 1 Aug 2018 15:12:18 -0400 Received: from localhost (D57E6652.static.ziggozakelijk.nl [213.126.102.82]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 85A0BD27; Wed, 1 Aug 2018 17:25:35 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nicholas Piggin , Michael Ellerman , Sasha Levin Subject: [PATCH 4.9 026/144] powerpc/64s: Fix compiler store ordering to SLB shadow area Date: Wed, 1 Aug 2018 18:50:53 +0200 Message-Id: <20180801164951.143983134@linuxfoundation.org> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180801164949.023217860@linuxfoundation.org> References: <20180801164949.023217860@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Nicholas Piggin [ Upstream commit 926bc2f100c24d4842b3064b5af44ae964c1d81c ] The stores to update the SLB shadow area must be made as they appear in the C code, so that the hypervisor does not see an entry with mismatched vsid and esid. Use WRITE_ONCE for this. GCC has been observed to elide the first store to esid in the update, which means that if the hypervisor interrupts the guest after storing to vsid, it could see an entry with old esid and new vsid, which may possibly result in memory corruption. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/mm/slb.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/arch/powerpc/mm/slb.c +++ b/arch/powerpc/mm/slb.c @@ -68,14 +68,14 @@ static inline void slb_shadow_update(uns * updating it. No write barriers are needed here, provided * we only update the current CPU's SLB shadow buffer. */ - p->save_area[index].esid = 0; - p->save_area[index].vsid = cpu_to_be64(mk_vsid_data(ea, ssize, flags)); - p->save_area[index].esid = cpu_to_be64(mk_esid_data(ea, ssize, index)); + WRITE_ONCE(p->save_area[index].esid, 0); + WRITE_ONCE(p->save_area[index].vsid, cpu_to_be64(mk_vsid_data(ea, ssize, flags))); + WRITE_ONCE(p->save_area[index].esid, cpu_to_be64(mk_esid_data(ea, ssize, index))); } static inline void slb_shadow_clear(enum slb_index index) { - get_slb_shadow()->save_area[index].esid = 0; + WRITE_ONCE(get_slb_shadow()->save_area[index].esid, 0); } static inline void create_shadowed_slbe(unsigned long ea, int ssize,