From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1423520AbeE1LIB (ORCPT ); Mon, 28 May 2018 07:08:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:54606 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1423463AbeE1LHk (ORCPT ); Mon, 28 May 2018 07:07:40 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "David H. Gutteridge" , Joerg Roedel , Thomas Gleixner , Andrea Arcangeli , Andy Lutomirski , Boris Ostrovsky , Borislav Petkov , Brian Gerst , Dave Hansen , David Laight , Denys Vlasenko , Eduardo Valentin , Jiri Kosina , Josh Poimboeuf , Juergen Gross , Linus Torvalds , Pavel Machek , Peter Zijlstra , Waiman Long , Will Deacon , aliguori@amazon.com, daniel.gruss@iaik.tugraz.at, hughd@google.com, keescook@google.com, linux-mm@kvack.org, Ingo Molnar , Sasha Levin Subject: [PATCH 4.16 050/272] x86/pgtable: Dont set huge PUD/PMD on non-leaf entries Date: Mon, 28 May 2018 12:01:23 +0200 Message-Id: <20180528100245.071626281@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180528100240.256525891@linuxfoundation.org> References: <20180528100240.256525891@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 List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Joerg Roedel [ Upstream commit e3e288121408c3abeed5af60b87b95c847143845 ] The pmd_set_huge() and pud_set_huge() functions are used from the generic ioremap() code to establish large mappings where this is possible. But the generic ioremap() code does not check whether the PMD/PUD entries are already populated with a non-leaf entry, so that any page-table pages these entries point to will be lost. Further, on x86-32 with SHARED_KERNEL_PMD=0, this causes a BUG_ON() in vmalloc_sync_one() when PMD entries are synced from swapper_pg_dir to the current page-table. This happens because the PMD entry from swapper_pg_dir was promoted to a huge-page entry while the current PGD still contains the non-leaf entry. Because both entries are present and point to a different page, the BUG_ON() triggers. This was actually triggered with pti-x32 enabled in a KVM virtual machine by the graphics driver. A real and better fix for that would be to improve the page-table handling in the generic ioremap() code. But that is out-of-scope for this patch-set and left for later work. Reported-by: David H. Gutteridge Signed-off-by: Joerg Roedel Reviewed-by: Thomas Gleixner Cc: Andrea Arcangeli Cc: Andy Lutomirski Cc: Boris Ostrovsky Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: David Laight Cc: Denys Vlasenko Cc: Eduardo Valentin Cc: Greg KH Cc: Jiri Kosina Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Linus Torvalds Cc: Pavel Machek Cc: Peter Zijlstra Cc: Waiman Long Cc: Will Deacon Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20180411152437.GC15462@8bytes.org Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- arch/x86/mm/pgtable.c | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -1,6 +1,7 @@ // SPDX-License-Identifier: GPL-2.0 #include #include +#include #include #include #include @@ -636,6 +637,10 @@ int pud_set_huge(pud_t *pud, phys_addr_t (mtrr != MTRR_TYPE_WRBACK)) return 0; + /* Bail out if we are we on a populated non-leaf entry: */ + if (pud_present(*pud) && !pud_huge(*pud)) + return 0; + prot = pgprot_4k_2_large(prot); set_pte((pte_t *)pud, pfn_pte( @@ -664,6 +669,10 @@ int pmd_set_huge(pmd_t *pmd, phys_addr_t return 0; } + /* Bail out if we are we on a populated non-leaf entry: */ + if (pmd_present(*pmd) && !pmd_huge(*pmd)) + return 0; + prot = pgprot_4k_2_large(prot); set_pte((pte_t *)pmd, pfn_pte(