[tip:mm/pkeys] x86/mm/pkeys: Add Kconfig option

[tip-bot for Dave Hansen]

Commit-ID:  35e97790f5f1e5cf2b5522c55e3e31d5c81bd226
Gitweb:     http://git.kernel.org/tip/35e97790f5f1e5cf2b5522c55e3e31d5c81bd226
Author:     Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
AuthorDate: Fri, 12 Feb 2016 13:02:00 -0800
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 16 Feb 2016 10:11:13 +0100

x86/mm/pkeys: Add Kconfig option

I don't have a strong opinion on whether we need a Kconfig prompt
or not.  Protection Keys has relatively little code associated
with it, and it is not a heavyweight feature to keep enabled.
However, I can imagine that folks would still appreciate being
able to disable it.

Note that, with disabled-features.h, the checks in the code
for protection keys are always the same:

	cpu_has(c, X86_FEATURE_PKU)

With the config option disabled, this essentially turns into an

We will hide the prompt for now.

Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Dave Hansen <dave@xxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Link: http://lkml.kernel.org/r/20160212210200.DB7055E8@xxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/Kconfig | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index ab2ed53..3632cdd 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1714,6 +1714,10 @@ config X86_INTEL_MPX
 
 	  If unsure, say N.
 
+config X86_INTEL_MEMORY_PROTECTION_KEYS
+	def_bool y
+	depends on CPU_SUP_INTEL && X86_64
+
 config EFI
 	bool "EFI runtime service support"
 	depends on ACPI