x86/fpu, x86/mm/pkeys: Add PKRU xsave fields and data structures

The protection keys register (PKRU) is saved and restored using
xsave.  Define the data structure that we will use to access it
inside the xsave buffer.

Note that we also have to widen the printk of the xsave feature
masks since this is feature 0x200 and we only did two characters
before.

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/20160212210204.56DF8F7B@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/include/asm/fpu/types.h

@@ -109,6 +109,7 @@ enum xfeature {
 	XFEATURE_ZMM_Hi256,
 	XFEATURE_Hi16_ZMM,
 	XFEATURE_PT_UNIMPLEMENTED_SO_FAR,
+	XFEATURE_PKRU,
 
 	XFEATURE_MAX,
 };
@@ -121,6 +122,7 @@ enum xfeature {
 #define XFEATURE_MASK_OPMASK		(1 << XFEATURE_OPMASK)
 #define XFEATURE_MASK_ZMM_Hi256		(1 << XFEATURE_ZMM_Hi256)
 #define XFEATURE_MASK_Hi16_ZMM		(1 << XFEATURE_Hi16_ZMM)
+#define XFEATURE_MASK_PKRU		(1 << XFEATURE_PKRU)
 
 #define XFEATURE_MASK_FPSSE		(XFEATURE_MASK_FP | XFEATURE_MASK_SSE)
 #define XFEATURE_MASK_AVX512		(XFEATURE_MASK_OPMASK \
@@ -213,6 +215,15 @@ struct avx_512_hi16_state {
 	struct reg_512_bit		hi16_zmm[16];
 } __packed;
 
+/*
+ * State component 9: 32-bit PKRU register.  The state is
+ * 8 bytes long but only 4 bytes is used currently.
+ */
+struct pkru_state {
+	u32				pkru;
+	u32				pad;
+} __packed;
+
 struct xstate_header {
 	u64				xfeatures;
 	u64				xcomp_bv;

arch/x86/include/asm/fpu/xstate.h

@@ -28,7 +28,8 @@
 				 XFEATURE_MASK_YMM | \
 				 XFEATURE_MASK_OPMASK | \
 				 XFEATURE_MASK_ZMM_Hi256 | \
-				 XFEATURE_MASK_Hi16_ZMM)
+				 XFEATURE_MASK_Hi16_ZMM	 | \
+				 XFEATURE_MASK_PKRU)
 
 /* All currently supported features */
 #define XCNTXT_MASK	(XFEATURE_MASK_LAZY | XFEATURE_MASK_EAGER)

arch/x86/kernel/fpu/xstate.c

@@ -29,6 +29,8 @@ static const char *xfeature_names[] =
 	"AVX-512 Hi256"			,
 	"AVX-512 ZMM_Hi256"		,
 	"Processor Trace (unused)"	,
+	"Protection Keys User registers",
+	"unknown xstate feature"	,
 };
 
 /*
@@ -58,6 +60,7 @@ void fpu__xstate_clear_all_cpu_caps(void)
 	setup_clear_cpu_cap(X86_FEATURE_AVX512CD);
 	setup_clear_cpu_cap(X86_FEATURE_MPX);
 	setup_clear_cpu_cap(X86_FEATURE_XGETBV1);
+	setup_clear_cpu_cap(X86_FEATURE_PKU);
 }
 
 /*
@@ -236,7 +239,7 @@ static void __init print_xstate_feature(u64 xstate_mask)
 	const char *feature_name;
 
 	if (cpu_has_xfeatures(xstate_mask, &feature_name))
-		pr_info("x86/fpu: Supporting XSAVE feature 0x%02Lx: '%s'\n", xstate_mask, feature_name);
+		pr_info("x86/fpu: Supporting XSAVE feature 0x%03Lx: '%s'\n", xstate_mask, feature_name);
 }
 
 /*
@@ -252,6 +255,7 @@ static void __init print_xstate_features(void)
 	print_xstate_feature(XFEATURE_MASK_OPMASK);
 	print_xstate_feature(XFEATURE_MASK_ZMM_Hi256);
 	print_xstate_feature(XFEATURE_MASK_Hi16_ZMM);
+	print_xstate_feature(XFEATURE_MASK_PKRU);
 }
 
 /*
@@ -468,6 +472,7 @@ static void check_xstate_against_struct(int nr)
 	XCHECK_SZ(sz, nr, XFEATURE_OPMASK,    struct avx_512_opmask_state);
 	XCHECK_SZ(sz, nr, XFEATURE_ZMM_Hi256, struct avx_512_zmm_uppers_state);
 	XCHECK_SZ(sz, nr, XFEATURE_Hi16_ZMM,  struct avx_512_hi16_state);
+	XCHECK_SZ(sz, nr, XFEATURE_PKRU,      struct pkru_state);
 
 	/*
 	 * Make *SURE* to add any feature numbers in below if