x86/cpufeature, x86/mm/pkeys: Add protection keys related CPUID definitions

BugLink: https://bugs.launchpad.net/bugs/1790620

commit dfb4a70f upstream

There are two CPUID bits for protection keys.  One is for whether
the CPU contains the feature, and the other will appear set once
the OS enables protection keys.  Specifically:

	Bit 04: OSPKE. If 1, OS has set CR4.PKE to enable
	Protection keys (and the RDPKRU/WRPKRU instructions)

This is because userspace can not see CR4 contents, but it can
see CPUID contents.

X86_FEATURE_PKU is referred to as "PKU" in the hardware documentation:

	CPUID.(EAX=07H,ECX=0H):ECX.PKU [bit 3]

X86_FEATURE_OSPKE is "OSPKU":

	CPUID.(EAX=07H,ECX=0H):ECX.OSPKE [bit 4]

These are the first CPU features which need to look at the
ECX word in CPUID leaf 0x7, so this patch also includes
fetching that word in to the cpuinfo->x86_capability[] array.

Add it to the disabled-features mask when its config option is
off.  Even though we are not using it here, we also extend the
REQUIRED_MASK_BIT_SET() macro to keep it mirroring the
DISABLED_MASK_BIT_SET() version.

This means that in almost all code, you should use:

	cpu_has(c, X86_FEATURE_PKU)

and *not* the CONFIG option.
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/20160212210201.7714C250@viggo.jf.intel.comSigned-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Srivatsa S. Bhat <srivatsa@csail.mit.edu>
Reviewed-by: Matt Helsley (VMware) <matt.helsley@gmail.com>
Reviewed-by: Alexey Makhalov <amakhalov@vmware.com>
Reviewed-by: Bo Gan <ganb@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

arch/x86/include/asm/cpufeature.h

@@ -100,6 +100,10 @@ extern const char * const x86_bug_flags[NBUGINTS*32];
 	(__builtin_constant_p(bit) && REQUIRED_MASK_BIT_SET(bit) ? 1 : 	\
 	 x86_this_cpu_test_bit(bit, (unsigned long *)&cpu_info.x86_capability))
 
+/* Intel-defined CPU features, CPUID level 0x00000007:0 (ecx), word 16 */
+#define X86_FEATURE_PKU		(16*32+ 3) /* Protection Keys for Userspace */
+#define X86_FEATURE_OSPKE	(16*32+ 4) /* OS Protection Keys Enable */
+
 /*
  * This macro is for detection of features which need kernel
  * infrastructure to be used.  It may *not* directly test the CPU

arch/x86/include/asm/disabled-features.h

@@ -30,6 +30,14 @@
 # define DISABLE_PCID		(1<<(X86_FEATURE_PCID & 31))
 #endif /* CONFIG_X86_64 */
 
+#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
+# define DISABLE_PKU		(1<<(X86_FEATURE_PKU))
+# define DISABLE_OSPKE		(1<<(X86_FEATURE_OSPKE))
+#else
+# define DISABLE_PKU		0
+# define DISABLE_OSPKE		0
+#endif /* CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS */
+
 #ifdef CONFIG_PAGE_TABLE_ISOLATION
 # define DISABLE_KAISER		0
 #else

arch/x86/kernel/cpu/common.c

@@ -725,6 +725,7 @@ void get_cpu_cap(struct cpuinfo_x86 *c)
 	if (c->cpuid_level >= 0x00000007) {
 		cpuid_count(0x00000007, 0, &eax, &ebx, &ecx, &edx);
 		c->x86_capability[CPUID_7_0_EBX] = ebx;
+		c->x86_capability[CPUID_7_ECX] = ecx;
 		c->x86_capability[CPUID_7_EDX] = edx;
 	}