x86/fpu: Remove 'xfeature_nr'

xfeature_nr ended up being initialized too late for me to
use it in the "xsave size sanity check" patch which is
later in the series.  I tried to move around its initialization
but realized that it was just as easy to get rid of it.

We only have 9 XFEATURES.  Instead of dynamically calculating
and storing the last feature, just use the compile-time max:
XFEATURES_NR_MAX.  Note that even with 'xfeatures_nr' we can
had "holes" in the xfeatures_mask that we had to deal with.

We also change a 'leaf' variable to be a plain 'i'.  Although
it is used to grab a cpuid leaf in this one loop, all of the
other loops just use an 'i' and I find it much more obvious
to keep the naming consistent across all the similar loops.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: dave@sr71.net
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/20150902233128.3F30DF5A@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/fpu/xstate.c

@@ -35,9 +35,6 @@ static unsigned int xstate_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] =
 static unsigned int xstate_sizes[XFEATURE_MAX]   = { [ 0 ... XFEATURE_MAX - 1] = -1};
 static unsigned int xstate_comp_offsets[sizeof(xfeatures_mask)*8];
 
-/* The number of supported xfeatures in xfeatures_mask: */
-static unsigned int xfeatures_nr;
-
 /*
  * Clear all of the X86_FEATURE_* bits that are unavailable
  * when the CPU has no XSAVE support.
@@ -190,23 +187,18 @@ void fpu__init_cpu_xstate(void)
 /*
  * Record the offsets and sizes of various xstates contained
  * in the XSAVE state memory layout.
- *
- * ( Note that certain features might be non-present, for them
- *   we'll have 0 offset and 0 size. )
  */
 static void __init setup_xstate_features(void)
 {
-	u32 eax, ebx, ecx, edx, leaf;
+	u32 eax, ebx, ecx, edx, i;
 
-	xfeatures_nr = fls64(xfeatures_mask);
+	for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
+		cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
 
-	for (leaf = FIRST_EXTENDED_XFEATURE; leaf < xfeatures_nr; leaf++) {
-		cpuid_count(XSTATE_CPUID, leaf, &eax, &ebx, &ecx, &edx);
+		xstate_offsets[i] = ebx;
+		xstate_sizes[i] = eax;
 
-		xstate_offsets[leaf] = ebx;
-		xstate_sizes[leaf] = eax;
-
-		printk(KERN_INFO "x86/fpu: xstate_offset[%d]: %4d, xstate_sizes[%d]: %4d\n", leaf, ebx, leaf, eax);
+		printk(KERN_INFO "x86/fpu: xstate_offset[%d]: %4d, xstate_sizes[%d]: %4d\n", i, ebx, i, eax);
 	}
 }
 
@@ -252,7 +244,7 @@ static void __init setup_xstate_comp(void)
 	xstate_comp_offsets[1] = offsetof(struct fxregs_state, xmm_space);
 
 	if (!cpu_has_xsaves) {
-		for (i = FIRST_EXTENDED_XFEATURE; i < xfeatures_nr; i++) {
+		for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 			if (test_bit(i, (unsigned long *)&xfeatures_mask)) {
 				xstate_comp_offsets[i] = xstate_offsets[i];
 				xstate_comp_sizes[i] = xstate_sizes[i];
@@ -264,7 +256,7 @@ static void __init setup_xstate_comp(void)
 	xstate_comp_offsets[FIRST_EXTENDED_XFEATURE] =
 		FXSAVE_SIZE + XSAVE_HDR_SIZE;
 
-	for (i = FIRST_EXTENDED_XFEATURE; i < xfeatures_nr; i++) {
+	for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 		if (test_bit(i, (unsigned long *)&xfeatures_mask))
 			xstate_comp_sizes[i] = xstate_sizes[i];
 		else