[tip: x86/mm] x86/mm: Enable 5-level paging support by default

[tip-bot2 for Kirill A. Shutemov]

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     18ec1eaf58fbf2d9009a752a102a3d8e0d905a0f
Gitweb:        https://git.kernel.org/tip/18ec1eaf58fbf2d9009a752a102a3d8e0d905a0f
Author:        Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
AuthorDate:    Fri, 13 Sep 2019 12:54:52 +03:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Mon, 16 Sep 2019 16:51:20 +02:00

x86/mm: Enable 5-level paging support by default

Support of boot-time switching between 4- and 5-level paging mode is
upstream since 4.17.

We run internal testing with 5-level paging support enabled for a while
and it doesn't not cause any functional or performance regression on
4-level paging hardware.

The only 5-level paging related regressions I saw were in early boot
code that runs independently from CONFIG_X86_5LEVEL.

The next major release of distributions expected to have
CONFIG_X86_5LEVEL=y.

Enable the option by default. It may help to catch obscure bugs early.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Acked-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Link: https://lkml.kernel.org/r/20190913095452.40592-1-kirill.shutemov@xxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 58eae28..d4bbebe 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1483,6 +1483,7 @@ config X86_PAE
 
 config X86_5LEVEL
 	bool "Enable 5-level page tables support"
+	default y
 	select DYNAMIC_MEMORY_LAYOUT
 	select SPARSEMEM_VMEMMAP
 	depends on X86_64