From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753925AbdIRK4R (ORCPT ); Mon, 18 Sep 2017 06:56:17 -0400 Received: from mga03.intel.com ([134.134.136.65]:48036 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752150AbdIRK4O (ORCPT ); Mon, 18 Sep 2017 06:56:14 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.42,412,1500966000"; d="scan'208";a="901293289" From: "Kirill A. Shutemov" To: Ingo Molnar , Linus Torvalds , x86@kernel.org, Thomas Gleixner , "H. Peter Anvin" Cc: Andrew Morton , Andy Lutomirski , Cyrill Gorcunov , Borislav Petkov , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCHv7 06/19] x86/boot/compressed/64: Detect and handle 5-level paging at boot-time Date: Mon, 18 Sep 2017 13:55:40 +0300 Message-Id: <20170918105553.27914-7-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20170918105553.27914-1-kirill.shutemov@linux.intel.com> References: <20170918105553.27914-1-kirill.shutemov@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch prepare decompression code to boot-time switching between 4- and 5-level paging. Signed-off-by: Kirill A. Shutemov --- arch/x86/boot/compressed/head_64.S | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index b4a5d284391c..09c85e8558eb 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -288,6 +288,28 @@ ENTRY(startup_64) leaq boot_stack_end(%rbx), %rsp #ifdef CONFIG_X86_5LEVEL + /* Preserve rbx across cpuid */ + movq %rbx, %r8 + + /* Check if leaf 7 is supported */ + xorl %eax, %eax + cpuid + cmpl $7, %eax + jb lvl5 + + /* + * Check if la57 is supported. + * The feature is enumerated with CPUID.(EAX=07H, ECX=0):ECX[bit 16] + */ + movl $7, %eax + xorl %ecx, %ecx + cpuid + andl $(1 << 16), %ecx + jz lvl5 + + /* Restore rbx */ + movq %r8, %rbx + /* Check if 5-level paging has already enabled */ movq %cr4, %rax testl $X86_CR4_LA57, %eax @@ -327,6 +349,8 @@ ENTRY(startup_64) pushq %rax lretq lvl5: + /* Restore rbx */ + movq %r8, %rbx #endif /* Zero EFLAGS */ -- 2.14.1