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@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20160212210200.DB7055E8@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index ab2ed5328f0a87c976a7fbbea31cc018d4a9c29d..3632cdd03201bf1b1b6fb50b95084917b09000da 100644 (file)
--- 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