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>

1 files changed, 2 insertions, 2 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ac24889c8bc3..0b58b9397098 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3197,7 +3197,7 @@ static int kvm_vcpu_ioctl_x86_set_debugregs(struct kvm_vcpu *vcpu,
 static void fill_xsave(u8 *dest, struct kvm_vcpu *vcpu)
 {
 	struct xsave_struct *xsave = &vcpu->arch.guest_fpu.state->xsave;
-	u64 xstate_bv = xsave->header.xstate_bv;
+	u64 xstate_bv = xsave->header.xfeatures;
 	u64 valid;
 
 	/*
@@ -3243,7 +3243,7 @@ static void load_xsave(struct kvm_vcpu *vcpu, u8 *src)
 	memcpy(xsave, src, XSAVE_HDR_OFFSET);
 
 	/* Set XSTATE_BV and possibly XCOMP_BV.  */
-	xsave->header.xstate_bv = xstate_bv;
+	xsave->header.xfeatures = xstate_bv;
 	if (cpu_has_xsaves)
 		xsave->header.xcomp_bv = host_xcr0 | XSTATE_COMPACTION_ENABLED;