From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f199.google.com (mail-pf0-f199.google.com [209.85.192.199]) by kanga.kvack.org (Postfix) with ESMTP id B44076B0253 for ; Fri, 20 Oct 2017 15:59:41 -0400 (EDT) Received: by mail-pf0-f199.google.com with SMTP id 76so11568777pfr.3 for ; Fri, 20 Oct 2017 12:59:41 -0700 (PDT) Received: from mga02.intel.com (mga02.intel.com. [134.134.136.20]) by mx.google.com with ESMTPS id m123si1110313pgm.712.2017.10.20.12.59.40 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 20 Oct 2017 12:59:40 -0700 (PDT) From: "Kirill A. Shutemov" Subject: [PATCH 2/4] x86/boot/compressed/64: Detect and handle 5-level paging at boot-time Date: Fri, 20 Oct 2017 22:59:32 +0300 Message-Id: <20171020195934.32108-3-kirill.shutemov@linux.intel.com> In-Reply-To: <20171020195934.32108-1-kirill.shutemov@linux.intel.com> References: <20171020195934.32108-1-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: Andy Lutomirski , Cyrill Gorcunov , Borislav Petkov , Andi Kleen , 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 | 16 ++++++++++++---- arch/x86/boot/compressed/pagetable.c | 19 +++++++++++++++++++ 2 files changed, 31 insertions(+), 4 deletions(-) diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index b4a5d284391c..6ac8239af2b6 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -288,10 +288,18 @@ ENTRY(startup_64) leaq boot_stack_end(%rbx), %rsp #ifdef CONFIG_X86_5LEVEL - /* Check if 5-level paging has already enabled */ - movq %cr4, %rax - testl $X86_CR4_LA57, %eax - jnz lvl5 + /* + * Check if we need to enable 5-level paging. + * RSI holds real mode data and need to be preserved across + * a function call. + */ + pushq %rsi + call need_to_enabled_l5 + popq %rsi + + /* If need_to_enabled_l5() returned zero, we're done here. */ + cmpq $0, %rax + je lvl5 /* * At this point we are in long mode with 4-level paging enabled, diff --git a/arch/x86/boot/compressed/pagetable.c b/arch/x86/boot/compressed/pagetable.c index f1aa43854bed..76d25a82e3ac 100644 --- a/arch/x86/boot/compressed/pagetable.c +++ b/arch/x86/boot/compressed/pagetable.c @@ -149,3 +149,22 @@ void finalize_identity_maps(void) { write_cr3(top_level_pgt); } + +#ifdef CONFIG_X86_5LEVEL +int need_to_enabled_l5(void) +{ + /* Check i leaf 7 is supported. */ + if (native_cpuid_eax(0) < 7) + return 0; + + /* Check if la57 is supported. */ + if (!(native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31)))) + return 0; + + /* Check if 5-level paging has already been enabled. */ + if (native_read_cr4() & X86_CR4_LA57) + return 0; + + return 1; +} +#endif -- 2.14.2 -- 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