From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f199.google.com (mail-wr0-f199.google.com [209.85.128.199]) by kanga.kvack.org (Postfix) with ESMTP id A5D726B0003 for ; Wed, 21 Feb 2018 08:01:12 -0500 (EST) Received: by mail-wr0-f199.google.com with SMTP id 17so1363195wrm.10 for ; Wed, 21 Feb 2018 05:01:12 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id r141si16965906wmb.155.2018.02.21.05.01.10 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 21 Feb 2018 05:01:11 -0800 (PST) From: Greg Kroah-Hartman Subject: [PATCH 4.14 037/167] x86/kexec: Make kexec (mostly) work in 5-level paging mode Date: Wed, 21 Feb 2018 13:47:28 +0100 Message-Id: <20180221124526.630792321@linuxfoundation.org> In-Reply-To: <20180221124524.639039577@linuxfoundation.org> References: <20180221124524.639039577@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Baoquan He , "Kirill A. Shutemov" , Borislav Petkov , Linus Torvalds , Peter Zijlstra , Thomas Gleixner , linux-mm@kvack.org, Ingo Molnar 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kirill A. Shutemov commit 5bf30316991d5bcda046343ee77d823cf16fdd03 upstream. 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 Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/relocate_kernel_64.S | 8 ++++++++ 1 file changed, 8 insertions(+) --- 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org