x86/cpufeature: Add User-Mode Instruction Prevention definitions

[ Note, this is a Git cherry-pick of the following commit: (limited to the cpufeatures.h file)

    3522c2a ("x86/cpufeature: Add User-Mode Instruction Prevention definitions")

  ... for easier x86 PTI code testing and back-porting. ]

User-Mode Instruction Prevention is a security feature present in new
Intel processors that, when set, prevents the execution of a subset of
instructions if such instructions are executed in user mode (CPL > 0).
Attempting to execute such instructions causes a general protection
exception.

The subset of instructions comprises:

 * SGDT - Store Global Descriptor Table
 * SIDT - Store Interrupt Descriptor Table
 * SLDT - Store Local Descriptor Table
 * SMSW - Store Machine Status Word
 * STR  - Store Task Register

This feature is also added to the list of disabled-features to allow
a cleaner handling of build-time configuration.

Signed-off-by: Ricardo Neri <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Reviewed-by: Borislav Petkov <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Chen Yucong <[email protected]>
Cc: Chris Metcalf <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: Fenghua Yu <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Huang Rui <[email protected]>
Cc: Jiri Slaby <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Michael S. Tsirkin <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Cc: Paul Gortmaker <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Ravi V. Shankar <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/1509935277-22138-7-git-send-email-ricardo.neri-calderon@linux.intel.com
Signed-off-by: Ingo Molnar <[email protected]>

Author: ricardon

arch/x86/include/asm/cpufeatures.h

@@ -296,6 +296,7 @@
 
 /* Intel-defined CPU features, CPUID level 0x00000007:0 (ECX), word 16 */
 #define X86_FEATURE_AVX512VBMI		(16*32+ 1) /* AVX512 Vector Bit Manipulation instructions*/
+#define X86_FEATURE_UMIP		(16*32+ 2) /* User Mode Instruction Protection */
 #define X86_FEATURE_PKU			(16*32+ 3) /* Protection Keys for Userspace */
 #define X86_FEATURE_OSPKE		(16*32+ 4) /* OS Protection Keys Enable */
 #define X86_FEATURE_AVX512_VBMI2	(16*32+ 6) /* Additional AVX512 Vector Bit Manipulation Instructions */