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 8E1EDC43387 for ; Wed, 26 Dec 2018 22:40:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5A73B218EA for ; Wed, 26 Dec 2018 22:40:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1545864033; bh=u1iOgiWVnk6QY6n1+11h6CjOOFRYGt3kiupOh2ZXYKI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=YHtcMwuUH0xYcP/QdiRsnc1CgiD1OBJVM0H8KAkZQmmDqGTGeUK5LqW6GOjw5qpJ0 d8mgA1a4253+jazCzBATgVLGd3w7lNnPUJIGJpnl6aU1+UOp/uqARJJeGrEWNy1tEl 8CtJuaNUA5IW2MpgiO7yctc39hQSFi2YapQP7LJA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729071AbeLZWkc (ORCPT ); Wed, 26 Dec 2018 17:40:32 -0500 Received: from mail.kernel.org ([198.145.29.99]:40558 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729040AbeLZWkZ (ORCPT ); Wed, 26 Dec 2018 17:40:25 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (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 07109218E2; Wed, 26 Dec 2018 22:40:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1545864024; bh=u1iOgiWVnk6QY6n1+11h6CjOOFRYGt3kiupOh2ZXYKI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MwPAUht2kUwNYDcY1SThzpqbiQH1o6xkjQgWJYEp7Lmlbfo/Z3A6jgu9/fKwrxGuE MNCnc4je/T5CADpzUBFXl3OUaKPe4/xcanXTj9oLV/nNEZOdQ8zF8aH7j21395bdtc OxCOyMBrKAtQ2Xzr4Tz+n/pEh3SUxSjtWMvQqngU= From: Sasha Levin To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: "Kirill A. Shutemov" , Thomas Gleixner , bp@alien8.de, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, boris.ostrovsky@oracle.com, bhe@redhat.com, linux-mm@kvack.org, xen-devel@lists.xenproject.org, Sasha Levin Subject: [PATCH AUTOSEL 4.14 18/59] x86/mm: Fix guard hole handling Date: Wed, 26 Dec 2018 17:37:58 -0500 Message-Id: <20181226223839.150262-18-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20181226223839.150262-1-sashal@kernel.org> References: <20181226223839.150262-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Kirill A. Shutemov" [ Upstream commit 16877a5570e0c5f4270d5b17f9bab427bcae9514 ] There is a guard hole at the beginning of the kernel address space, also used by hypervisors. It occupies 16 PGD entries. This reserved range is not defined explicitely, it is calculated relative to other entities: direct mapping and user space ranges. The calculation got broken by recent changes of the kernel memory layout: LDT remap range is now mapped before direct mapping and makes the calculation invalid. The breakage leads to crash on Xen dom0 boot[1]. Define the reserved range explicitely. It's part of kernel ABI (hypervisors expect it to be stable) and must not depend on changes in the rest of kernel memory layout. [1] https://lists.xenproject.org/archives/html/xen-devel/2018-11/msg03313.html Fixes: d52888aa2753 ("x86/mm: Move LDT remap out of KASLR region on 5-level paging") Reported-by: Hans van Kranenburg Signed-off-by: Kirill A. Shutemov Signed-off-by: Thomas Gleixner Tested-by: Hans van Kranenburg Reviewed-by: Juergen Gross Cc: bp@alien8.de Cc: hpa@zytor.com Cc: dave.hansen@linux.intel.com Cc: luto@kernel.org Cc: peterz@infradead.org Cc: boris.ostrovsky@oracle.com Cc: bhe@redhat.com Cc: linux-mm@kvack.org Cc: xen-devel@lists.xenproject.org Link: https://lkml.kernel.org/r/20181130202328.65359-2-kirill.shutemov@linux.intel.com Signed-off-by: Sasha Levin --- arch/x86/include/asm/pgtable_64_types.h | 5 +++++ arch/x86/mm/dump_pagetables.c | 8 ++++---- arch/x86/xen/mmu_pv.c | 11 ++++++----- 3 files changed, 15 insertions(+), 9 deletions(-) diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h index 7764617b8f9c..bf6d2692fc60 100644 --- a/arch/x86/include/asm/pgtable_64_types.h +++ b/arch/x86/include/asm/pgtable_64_types.h @@ -94,6 +94,11 @@ typedef struct { pteval_t pte; } pte_t; # define __VMEMMAP_BASE _AC(0xffffea0000000000, UL) #endif +#define GUARD_HOLE_PGD_ENTRY -256UL +#define GUARD_HOLE_SIZE (16UL << PGDIR_SHIFT) +#define GUARD_HOLE_BASE_ADDR (GUARD_HOLE_PGD_ENTRY << PGDIR_SHIFT) +#define GUARD_HOLE_END_ADDR (GUARD_HOLE_BASE_ADDR + GUARD_HOLE_SIZE) + #define LDT_PGD_ENTRY -240UL #define LDT_BASE_ADDR (LDT_PGD_ENTRY << PGDIR_SHIFT) diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c index 2a4849e92831..cf403e057f3f 100644 --- a/arch/x86/mm/dump_pagetables.c +++ b/arch/x86/mm/dump_pagetables.c @@ -465,11 +465,11 @@ static inline bool is_hypervisor_range(int idx) { #ifdef CONFIG_X86_64 /* - * ffff800000000000 - ffff87ffffffffff is reserved for - * the hypervisor. + * A hole in the beginning of kernel address space reserved + * for a hypervisor. */ - return (idx >= pgd_index(__PAGE_OFFSET) - 16) && - (idx < pgd_index(__PAGE_OFFSET)); + return (idx >= pgd_index(GUARD_HOLE_BASE_ADDR)) && + (idx < pgd_index(GUARD_HOLE_END_ADDR)); #else return false; #endif diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c index b33fa127a613..7631e6130d44 100644 --- a/arch/x86/xen/mmu_pv.c +++ b/arch/x86/xen/mmu_pv.c @@ -614,19 +614,20 @@ static int __xen_pgd_walk(struct mm_struct *mm, pgd_t *pgd, unsigned long limit) { int i, nr, flush = 0; - unsigned hole_low, hole_high; + unsigned hole_low = 0, hole_high = 0; /* The limit is the last byte to be touched */ limit--; BUG_ON(limit >= FIXADDR_TOP); +#ifdef CONFIG_X86_64 /* * 64-bit has a great big hole in the middle of the address - * space, which contains the Xen mappings. On 32-bit these - * will end up making a zero-sized hole and so is a no-op. + * space, which contains the Xen mappings. */ - hole_low = pgd_index(USER_LIMIT); - hole_high = pgd_index(PAGE_OFFSET); + hole_low = pgd_index(GUARD_HOLE_BASE_ADDR); + hole_high = pgd_index(GUARD_HOLE_END_ADDR); +#endif nr = pgd_index(limit) + 1; for (i = 0; i < nr; i++) { -- 2.19.1