linux-kernel - [PATCH 2/2] KVM: x86: save one bit in ctxt->d

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Message-Id: <20161026205014.19801-3-rkrcmar@redhat.com>
Date:   Wed, 26 Oct 2016 22:50:14 +0200
From:   Radim Krčmář <rkrcmar@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Laszlo Ersek <lersek@...hat.com>
Subject: [PATCH 2/2] KVM: x86: save one bit in ctxt->d

Alignments are exclusive, so 5 modes can be expressed in 3 bits.

Signed-off-by: Radim Krčmář <rkrcmar@...hat.com>
---
 arch/x86/kvm/emulate.c | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index f360876d6b7f..8fe2dbfb6338 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -158,9 +158,11 @@
 #define Src2GS      (OpGS << Src2Shift)
 #define Src2Mask    (OpMask << Src2Shift)
 #define Mmx         ((u64)1 << 40)  /* MMX Vector instruction */
+#define AlignMask   ((u64)7 << 41)
 #define Aligned     ((u64)1 << 41)  /* Explicitly aligned (e.g. MOVDQA) */
-#define Unaligned   ((u64)1 << 42)  /* Explicitly unaligned (e.g. MOVDQU) */
-#define Avx         ((u64)1 << 43)  /* Advanced Vector Extensions */
+#define Unaligned   ((u64)2 << 41)  /* Explicitly unaligned (e.g. MOVDQU) */
+#define Avx         ((u64)3 << 41)  /* Advanced Vector Extensions */
+#define Aligned16   ((u64)4 << 41)  /* Aligned to 16 byte boundary (e.g. FXSAVE) */
 #define Fastop      ((u64)1 << 44)  /* Use opcode::u.fastop */
 #define NoWrite     ((u64)1 << 45)  /* No writeback */
 #define SrcWrite    ((u64)1 << 46)  /* Write back src operand */
@@ -171,7 +173,6 @@
 #define NearBranch  ((u64)1 << 52)  /* Near branches */
 #define No16	    ((u64)1 << 53)  /* No 16 bit operand */
 #define IncSP       ((u64)1 << 54)  /* SP is incremented before ModRM calc */
-#define Aligned16   ((u64)1 << 55)  /* Aligned to 16 byte boundary (e.g. FXSAVE) */
 
 #define DstXacc     (DstAccLo | SrcAccHi | SrcWrite)
 
@@ -638,19 +639,21 @@ static void set_segment_selector(struct x86_emulate_ctxt *ctxt, u16 selector,
  */
 static unsigned insn_alignment(struct x86_emulate_ctxt *ctxt, unsigned size)
 {
+	u64 alignment = ctxt->d & AlignMask;
+
 	if (likely(size < 16))
 		return 1;
 
-	if (ctxt->d & Aligned)
-		return size;
-	else if (ctxt->d & Unaligned)
+	switch (alignment) {
+	case Unaligned:
+	case Avx:
 		return 1;
-	else if (ctxt->d & Avx)
-		return 1;
-	else if (ctxt->d & Aligned16)
+	case Aligned16:
 		return 16;
-	else
+	case Aligned:
+	default:
 		return size;
+	}
 }
 
 static __always_inline int __linearize(struct x86_emulate_ctxt *ctxt,
-- 
2.10.1