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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 37B1FC64EAD for ; Sat, 29 Sep 2018 21:56:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 02C792087A for ; Sat, 29 Sep 2018 21:56:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 02C792087A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk 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 S1728522AbeI3ES2 (ORCPT ); Sun, 30 Sep 2018 00:18:28 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:51629 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727997AbeI3ESX (ORCPT ); Sun, 30 Sep 2018 00:18:23 -0400 Received: from [2a02:8011:400e:2:cbab:f00:c93f:614] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1g6N63-0000H2-Co; Sat, 29 Sep 2018 22:48:19 +0100 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1g6N5z-0006yb-JK; Sat, 29 Sep 2018 22:48:15 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Thomas Gleixner" , "Andi Kleen" Date: Sat, 29 Sep 2018 22:43:07 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 121/131] x86/mm/kmmio: Make the tracer robust against L1TF In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:cbab:f00:c93f:614 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.59-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Andi Kleen commit 1063711b57393c1999248cccb57bebfaf16739e7 upstream. The mmio tracer sets io mapping PTEs and PMDs to non present when enabled without inverting the address bits, which makes the PTE entry vulnerable for L1TF. Make it use the right low level macros to actually invert the address bits to protect against L1TF. In principle this could be avoided because MMIO tracing is not likely to be enabled on production machines, but the fix is straigt forward and for consistency sake it's better to get rid of the open coded PTE manipulation. Signed-off-by: Andi Kleen Signed-off-by: Thomas Gleixner Signed-off-by: Ben Hutchings --- arch/x86/mm/kmmio.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-) --- a/arch/x86/mm/kmmio.c +++ b/arch/x86/mm/kmmio.c @@ -114,24 +114,29 @@ static struct kmmio_fault_page *get_kmmi static void clear_pmd_presence(pmd_t *pmd, bool clear, pmdval_t *old) { + pmd_t new_pmd; pmdval_t v = pmd_val(*pmd); if (clear) { - *old = v & _PAGE_PRESENT; - v &= ~_PAGE_PRESENT; - } else /* presume this has been called with clear==true previously */ - v |= *old; - set_pmd(pmd, __pmd(v)); + *old = v; + new_pmd = pmd_mknotpresent(*pmd); + } else { + /* Presume this has been called with clear==true previously */ + new_pmd = __pmd(*old); + } + set_pmd(pmd, new_pmd); } static void clear_pte_presence(pte_t *pte, bool clear, pteval_t *old) { pteval_t v = pte_val(*pte); if (clear) { - *old = v & _PAGE_PRESENT; - v &= ~_PAGE_PRESENT; - } else /* presume this has been called with clear==true previously */ - v |= *old; - set_pte_atomic(pte, __pte(v)); + *old = v; + /* Nothing should care about address */ + pte_clear(&init_mm, 0, pte); + } else { + /* Presume this has been called with clear==true previously */ + set_pte_atomic(pte, __pte(*old)); + } } static int clear_page_presence(struct kmmio_fault_page *f, bool clear)