From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752656AbeDDXdA (ORCPT ); Wed, 4 Apr 2018 19:33:00 -0400 Received: from terminus.zytor.com ([198.137.202.136]:57665 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752395AbeDDXc5 (ORCPT ); Wed, 4 Apr 2018 19:32:57 -0400 Date: Wed, 4 Apr 2018 16:31:28 -0700 From: tip-bot for Sai Praneeth Message-ID: Cc: jlee@suse.com, ravi.v.shankar@intel.com, matt@codeblueprint.co.uk, a.p.zijlstra@chello.nl, luto@kernel.org, akpm@linux-foundation.org, tony.luck@intel.com, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, mingo@kernel.org, dave.hansen@intel.com, mst@redhat.com, ricardo.neri@intel.com, sai.praneeth.prakhya@intel.com, hpa@zytor.com, ard.biesheuvel@linaro.org, peterz@infradead.org, tglx@linutronix.de, bp@alien8.de Reply-To: hpa@zytor.com, ard.biesheuvel@linaro.org, tglx@linutronix.de, peterz@infradead.org, bp@alien8.de, a.p.zijlstra@chello.nl, matt@codeblueprint.co.uk, jlee@suse.com, ravi.v.shankar@intel.com, luto@kernel.org, tony.luck@intel.com, akpm@linux-foundation.org, mingo@kernel.org, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, sai.praneeth.prakhya@intel.com, ricardo.neri@intel.com, mst@redhat.com, dave.hansen@intel.com In-Reply-To: <1522870459-7432-1-git-send-email-sai.praneeth.prakhya@intel.com> References: <1522870459-7432-1-git-send-email-sai.praneeth.prakhya@intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:efi/urgent] x86/mm: Fix bogus warning during EFI bootup, use boot_cpu_has() instead of this_cpu_has() in build_cr3_noflush() Git-Commit-ID: 162ee5a8ab49be40d253f90e94aef712470a3a24 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: 162ee5a8ab49be40d253f90e94aef712470a3a24 Gitweb: https://git.kernel.org/tip/162ee5a8ab49be40d253f90e94aef712470a3a24 Author: Sai Praneeth AuthorDate: Wed, 4 Apr 2018 12:34:19 -0700 Committer: Ingo Molnar CommitDate: Thu, 5 Apr 2018 01:27:49 +0200 x86/mm: Fix bogus warning during EFI bootup, use boot_cpu_has() instead of this_cpu_has() in build_cr3_noflush() Linus reported the following boot warning: WARNING: CPU: 0 PID: 0 at arch/x86/include/asm/tlbflush.h:134 load_new_mm_cr3+0x114/0x170 [...] Call Trace: switch_mm_irqs_off+0x267/0x590 switch_mm+0xe/0x20 efi_switch_mm+0x3e/0x50 efi_enter_virtual_mode+0x43f/0x4da start_kernel+0x3bf/0x458 secondary_startup_64+0xa5/0xb0 ... after merging: 03781e40890c: x86/efi: Use efi_switch_mm() rather than manually twiddling with %cr3 When the platform supports PCID and if CONFIG_DEBUG_VM=y is enabled, build_cr3_noflush() (called via switch_mm()) does a sanity check to see if X86_FEATURE_PCID is set. Presently, build_cr3_noflush() uses "this_cpu_has(X86_FEATURE_PCID)" to perform the check but this_cpu_has() works only after SMP is initialized (i.e. per cpu cpu_info's should be populated) and this happens to be very late in the boot process (during rest_init()). As efi_runtime_services() are called during (early) kernel boot time and run time, modify build_cr3_noflush() to use boot_cpu_has() all the time. As suggested by Dave Hansen, this should be OK because all CPU's have same capabilities on x86. With this change the warning is fixed. ( Dave also suggested that we put a warning in this_cpu_has() if it's used early in the boot process. This is still work in progress as it affects MCE. ) Reported-by: Linus Torvalds Signed-off-by: Sai Praneeth Prakhya Cc: Andrew Morton Cc: Andy Lutomirski Cc: Ard Biesheuvel Cc: Borislav Petkov Cc: Dave Hansen Cc: Lee Chun-Yi Cc: Matt Fleming Cc: Michael S. Tsirkin Cc: Peter Zijlstra Cc: Peter Zijlstra Cc: Ravi Shankar Cc: Ricardo Neri Cc: Thomas Gleixner Cc: Tony Luck Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/1522870459-7432-1-git-send-email-sai.praneeth.prakhya@intel.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/tlbflush.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h index 84137c22fdfa..6690cd3fc8b1 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -131,7 +131,12 @@ static inline unsigned long build_cr3(pgd_t *pgd, u16 asid) static inline unsigned long build_cr3_noflush(pgd_t *pgd, u16 asid) { VM_WARN_ON_ONCE(asid > MAX_ASID_AVAILABLE); - VM_WARN_ON_ONCE(!this_cpu_has(X86_FEATURE_PCID)); + /* + * Use boot_cpu_has() instead of this_cpu_has() as this function + * might be called during early boot. This should work even after + * boot because all CPU's the have same capabilities: + */ + VM_WARN_ON_ONCE(!boot_cpu_has(X86_FEATURE_PCID)); return __sme_pa(pgd) | kern_pcid(asid) | CR3_NOFLUSH; }