From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752498AbdA1WT0 (ORCPT ); Sat, 28 Jan 2017 17:19:26 -0500 Received: from terminus.zytor.com ([65.50.211.136]:55196 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752481AbdA1WTM (ORCPT ); Sat, 28 Jan 2017 17:19:12 -0500 Date: Sat, 28 Jan 2017 14:16:57 -0800 From: tip-bot for Jiri Kosina Message-ID: Cc: hanka@ucw.cz, linux-kernel@vger.kernel.org, waiman.long@hpe.com, matt@codeblueprint.co.uk, hpa@zytor.com, vojtech@ucw.cz, bp@suse.de, peterz@infradead.org, jkosina@suse.cz, ard.biesheuvel@linaro.org, tglx@linutronix.de, mingo@kernel.org, bp@alien8.de, torvalds@linux-foundation.org, labbott@redhat.com Reply-To: matt@codeblueprint.co.uk, hpa@zytor.com, waiman.long@hpe.com, hanka@ucw.cz, linux-kernel@vger.kernel.org, vojtech@ucw.cz, bp@suse.de, peterz@infradead.org, jkosina@suse.cz, bp@alien8.de, ard.biesheuvel@linaro.org, mingo@kernel.org, tglx@linutronix.de, labbott@redhat.com, torvalds@linux-foundation.org In-Reply-To: <20170127222552.22336-1-matt@codeblueprint.co.uk> References: <20170127222552.22336-1-matt@codeblueprint.co.uk> To: linux-tip-commits@vger.kernel.org Subject: [tip:efi/urgent] x86/efi: Always map the first physical page into the EFI pagetables Git-Commit-ID: bf29bddf0417a4783da3b24e8c9e017ac649326f 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: bf29bddf0417a4783da3b24e8c9e017ac649326f Gitweb: http://git.kernel.org/tip/bf29bddf0417a4783da3b24e8c9e017ac649326f Author: Jiri Kosina AuthorDate: Fri, 27 Jan 2017 22:25:52 +0000 Committer: Ingo Molnar CommitDate: Sat, 28 Jan 2017 09:18:56 +0100 x86/efi: Always map the first physical page into the EFI pagetables Commit: 129766708 ("x86/efi: Only map RAM into EFI page tables if in mixed-mode") stopped creating 1:1 mappings for all RAM, when running in native 64-bit mode. It turns out though that there are 64-bit EFI implementations in the wild (this particular problem has been reported on a Lenovo Yoga 710-11IKB), which still make use of the first physical page for their own private use, even though they explicitly mark it EFI_CONVENTIONAL_MEMORY in the memory map. In case there is no mapping for this particular frame in the EFI pagetables, as soon as firmware tries to make use of it, a triple fault occurs and the system reboots (in case of the Yoga 710-11IKB this is very early during bootup). Fix that by always mapping the first page of physical memory into the EFI pagetables. We're free to hand this page to the BIOS, as trim_bios_range() will reserve the first page and isolate it away from memory allocators anyway. Note that just reverting 129766708 alone is not enough on v4.9-rc1+ to fix the regression on affected hardware, as this commit: ab72a27da ("x86/efi: Consolidate region mapping logic") later made the first physical frame not to be mapped anyway. Reported-by: Hanka Pavlikova Signed-off-by: Jiri Kosina Signed-off-by: Matt Fleming Cc: Ard Biesheuvel Cc: Borislav Petkov Cc: Borislav Petkov Cc: Laura Abbott Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Vojtech Pavlik Cc: Waiman Long Cc: linux-efi@vger.kernel.org Cc: stable@kernel.org # v4.8+ Fixes: 129766708 ("x86/efi: Only map RAM into EFI page tables if in mixed-mode") Link: http://lkml.kernel.org/r/20170127222552.22336-1-matt@codeblueprint.co.uk [ Tidied up the changelog and the comment. ] Signed-off-by: Ingo Molnar --- arch/x86/platform/efi/efi_64.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c index 319148b..2f25a36 100644 --- a/arch/x86/platform/efi/efi_64.c +++ b/arch/x86/platform/efi/efi_64.c @@ -269,6 +269,22 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages) efi_scratch.use_pgd = true; /* + * Certain firmware versions are way too sentimential and still believe + * they are exclusive and unquestionable owners of the first physical page, + * even though they explicitly mark it as EFI_CONVENTIONAL_MEMORY + * (but then write-access it later during SetVirtualAddressMap()). + * + * Create a 1:1 mapping for this page, to avoid triple faults during early + * boot with such firmware. We are free to hand this page to the BIOS, + * as trim_bios_range() will reserve the first page and isolate it away + * from memory allocators anyway. + */ + if (kernel_map_pages_in_pgd(pgd, 0x0, 0x0, 1, _PAGE_RW)) { + pr_err("Failed to create 1:1 mapping for the first page!\n"); + return 1; + } + + /* * When making calls to the firmware everything needs to be 1:1 * mapped and addressable with 32-bit pointers. Map the kernel * text and allocate a new stack because we can't rely on the