From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f72.google.com (mail-pg0-f72.google.com [74.125.83.72]) by kanga.kvack.org (Postfix) with ESMTP id 45B746B0261 for ; Mon, 18 Sep 2017 06:56:16 -0400 (EDT) Received: by mail-pg0-f72.google.com with SMTP id 188so163085pgb.3 for ; Mon, 18 Sep 2017 03:56:16 -0700 (PDT) Received: from mga14.intel.com (mga14.intel.com. [192.55.52.115]) by mx.google.com with ESMTPS id f6si4655269plf.94.2017.09.18.03.56.14 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 18 Sep 2017 03:56:14 -0700 (PDT) From: "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> In-Reply-To: <20170918105553.27914-1-kirill.shutemov@linux.intel.com> References: <20170918105553.27914-1-kirill.shutemov@linux.intel.com> Sender: owner-linux-mm@kvack.org List-ID: 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" 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 -- 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