From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752753AbcHKL73 (ORCPT ); Thu, 11 Aug 2016 07:59:29 -0400 Received: from terminus.zytor.com ([198.137.202.10]:53422 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752257AbcHKL7Z (ORCPT ); Thu, 11 Aug 2016 07:59:25 -0400 Date: Thu, 11 Aug 2016 04:58:20 -0700 From: tip-bot for Andy Lutomirski Message-ID: Cc: torvalds@linux-foundation.org, hpa@zytor.com, linux-kernel@vger.kernel.org, jpoimboe@redhat.com, brgerst@gmail.com, mingo@kernel.org, tglx@linutronix.de, dvlasenk@redhat.com, peterz@infradead.org, bp@alien8.de, mfleming@suse.de, luto@kernel.org, mjg59@srcf.ucam.org, mario_limonciello@dell.com Reply-To: mingo@kernel.org, tglx@linutronix.de, hpa@zytor.com, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, jpoimboe@redhat.com, brgerst@gmail.com, mfleming@suse.de, peterz@infradead.org, bp@alien8.de, luto@kernel.org, mario_limonciello@dell.com, mjg59@srcf.ucam.org, dvlasenk@redhat.com In-Reply-To: References: To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/urgent] x86/boot: Synchronize trampoline_cr4_features and mmu_cr4_features directly Git-Commit-ID: 18bc7bd523e0fc5be8d76bf84bde733a97a8c375 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 18bc7bd523e0fc5be8d76bf84bde733a97a8c375 Gitweb: http://git.kernel.org/tip/18bc7bd523e0fc5be8d76bf84bde733a97a8c375 Author: Andy Lutomirski AuthorDate: Wed, 10 Aug 2016 02:29:14 -0700 Committer: Ingo Molnar CommitDate: Thu, 11 Aug 2016 11:15:00 +0200 x86/boot: Synchronize trampoline_cr4_features and mmu_cr4_features directly The initialization process for trampoline_cr4_features and mmu_cr4_features was confusing. The intent is for mmu_cr4_features and *trampoline_cr4_features to stay in sync, but trampoline_cr4_features is NULL until setup_real_mode() runs. The old code synchronized *trampoline_cr4_features *twice*, once in setup_real_mode() and once in setup_arch(). It also initialized mmu_cr4_features in setup_real_mode(), which causes the actual value of mmu_cr4_features to potentially depend on when setup_real_mode() is called. With this patch, mmu_cr4_features is initialized directly in setup_arch(), and *trampoline_cr4_features is synchronized to mmu_cr4_features when the trampoline is set up. After this patch, it should be safe to defer setup_real_mode(). Signed-off-by: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Mario Limonciello Cc: Matt Fleming Cc: Matthew Garrett Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/d48a263f9912389b957dd495a7127b009259ffe0.1470821230.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/kernel/setup.c | 17 ++++++++++------- arch/x86/realmode/init.c | 3 ++- 2 files changed, 12 insertions(+), 8 deletions(-) diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index bf780e0..95c8c9c 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -1131,6 +1131,16 @@ void __init setup_arch(char **cmdline_p) early_trap_pf_init(); + /* + * Update mmu_cr4_features (and, indirectly, trampoline_cr4_features) + * with the current CR4 value. This may not be necessary, but + * auditing all the early-boot CR4 manipulation would be needed to + * rule it out. + */ + if (boot_cpu_data.cpuid_level >= 0) + /* A CPU has %cr4 if and only if it has CPUID. */ + mmu_cr4_features = __read_cr4(); + setup_real_mode(); memblock_set_current_limit(get_max_mapped()); @@ -1180,13 +1190,6 @@ void __init setup_arch(char **cmdline_p) kasan_init(); - if (boot_cpu_data.cpuid_level >= 0) { - /* A CPU has %cr4 if and only if it has CPUID */ - mmu_cr4_features = __read_cr4(); - if (trampoline_cr4_features) - *trampoline_cr4_features = mmu_cr4_features; - } - #ifdef CONFIG_X86_32 /* sync back kernel address range */ clone_pgd_range(initial_page_table + KERNEL_PGD_BOUNDARY, diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c index 705e3ff..c5bdc4e 100644 --- a/arch/x86/realmode/init.c +++ b/arch/x86/realmode/init.c @@ -4,6 +4,7 @@ #include #include #include +#include struct real_mode_header *real_mode_header; u32 *trampoline_cr4_features; @@ -84,7 +85,7 @@ void __init setup_real_mode(void) trampoline_header->start = (u64) secondary_startup_64; trampoline_cr4_features = &trampoline_header->cr4; - *trampoline_cr4_features = __read_cr4(); + *trampoline_cr4_features = mmu_cr4_features; trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd); trampoline_pgd[0] = trampoline_pgd_entry.pgd;