x86/fpu: Rename xsave.header::xstate_bv to 'xfeatures'

'xsave.header::xstate_bv' is a misnomer - what does 'bv' stand for?

It probably comes from the 'XGETBV' instruction name, but I could
not find in the Intel documentation where that abbreviation comes
from. It could mean 'bit vector' - or something else?

But how about - instead of guessing about a weird name - we named
the field in an obvious and descriptive way that tells us exactly
what it does?

So rename it to 'xfeatures', which is a bitmask of the
xfeatures that are fpstate_active in that context structure.

Eyesore like:

           fpu->state->xsave.xsave_hdr.xstate_bv |= XSTATE_FP;

is now much more readable:

           fpu->state->xsave.header.xfeatures |= XSTATE_FP;

Which form is not just infinitely more readable, but is also
shorter as well.

Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 2 insertions, 2 deletions

diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index 3007df99833e..07c6adc02f68 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -261,7 +261,7 @@ static inline int fpu_save_init(struct fpu *fpu)
 		/*
 		 * xsave header may indicate the init state of the FP.
 		 */
-		if (!(fpu->state->xsave.header.xstate_bv & XSTATE_FP))
+		if (!(fpu->state->xsave.header.xfeatures & XSTATE_FP))
 			return 1;
 	} else if (use_fxsr()) {
 		fpu_fxsave(fpu);
diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h
index 33c0c7b782db..9bd2cd1a19fd 100644
--- a/arch/x86/include/asm/fpu/types.h
+++ b/arch/x86/include/asm/fpu/types.h
@@ -100,7 +100,7 @@ struct bndcsr {
 } __packed;
 
 struct xstate_header {
-	u64				xstate_bv;
+	u64				xfeatures;
 	u64				xcomp_bv;
 	u64				reserved[6];
 } __attribute__((packed));