From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753319AbeAaJSI (ORCPT ); Wed, 31 Jan 2018 04:18:08 -0500 Received: from terminus.zytor.com ([65.50.211.136]:46135 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752089AbeAaJSE (ORCPT ); Wed, 31 Jan 2018 04:18:04 -0500 Date: Wed, 31 Jan 2018 01:13:40 -0800 From: "tip-bot for Kirill A. Shutemov" Message-ID: Cc: bp@suse.de, hpa@zytor.com, kirill.shutemov@linux.intel.com, linux-kernel@vger.kernel.org, peterz@infradead.org, bhe@redhat.com, tglx@linutronix.de, torvalds@linux-foundation.org, mingo@kernel.org Reply-To: kirill.shutemov@linux.intel.com, hpa@zytor.com, bp@suse.de, mingo@kernel.org, torvalds@linux-foundation.org, bhe@redhat.com, tglx@linutronix.de, peterz@infradead.org, linux-kernel@vger.kernel.org In-Reply-To: <20180129110845.26633-1-kirill.shutemov@linux.intel.com> References: <20180129110845.26633-1-kirill.shutemov@linux.intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/urgent] x86/kexec: Make kexec (mostly) work in 5-level paging mode Git-Commit-ID: 5bf30316991d5bcda046343ee77d823cf16fdd03 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: 5bf30316991d5bcda046343ee77d823cf16fdd03 Gitweb: https://git.kernel.org/tip/5bf30316991d5bcda046343ee77d823cf16fdd03 Author: Kirill A. Shutemov AuthorDate: Mon, 29 Jan 2018 14:08:45 +0300 Committer: Ingo Molnar CommitDate: Wed, 31 Jan 2018 08:39:40 +0100 x86/kexec: Make kexec (mostly) work in 5-level paging mode Currently kexec() will crash when switching into a 5-level paging enabled kernel. I missed that we need to change relocate_kernel() to set CR4.LA57 flag if the kernel has 5-level paging enabled. I avoided using #ifdef CONFIG_X86_5LEVEL here and inferred if we need to enable 5-level paging from previous CR4 value. This way the code is ready for boot-time switching between paging modes. With this patch applied, in addition to kexec 4-to-4 which always worked, we can kexec 4-to-5 and 5-to-5 - while 5-to-4 will need more work. Reported-by: Baoquan He Signed-off-by: Kirill A. Shutemov Tested-by: Baoquan He Cc: # v4.14+ Cc: Borislav Petkov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-mm@kvack.org Fixes: 77ef56e4f0fb ("x86: Enable 5-level paging support via CONFIG_X86_5LEVEL=y") Link: http://lkml.kernel.org/r/20180129110845.26633-1-kirill.shutemov@linux.intel.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/relocate_kernel_64.S | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S index 307d3ba..11eda21e 100644 --- a/arch/x86/kernel/relocate_kernel_64.S +++ b/arch/x86/kernel/relocate_kernel_64.S @@ -68,6 +68,9 @@ relocate_kernel: movq %cr4, %rax movq %rax, CR4(%r11) + /* Save CR4. Required to enable the right paging mode later. */ + movq %rax, %r13 + /* zero out flags, and disable interrupts */ pushq $0 popfq @@ -126,8 +129,13 @@ identity_mapped: /* * Set cr4 to a known state: * - physical address extension enabled + * - 5-level paging, if it was enabled before */ movl $X86_CR4_PAE, %eax + testq $X86_CR4_LA57, %r13 + jz 1f + orl $X86_CR4_LA57, %eax +1: movq %rax, %cr4 jmp 1f