[PATCH 10/13] KVM: x86 emulator: mix decode bits from opcode and group decode tables

[Avi Kivity <avi@redhat.com>]

Allow bits that are common to all members of a group to be specified in the
opcode table instead of the group table.  This allows some simplification
of the decode tables.

Signed-off-by: Avi Kivity <avi@redhat.com>
---
 arch/x86/kvm/emulate.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 9a2db88..8834672 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -955,7 +955,7 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
 	struct decode_cache *c = &ctxt->decode;
 	int rc = X86EMUL_CONTINUE;
 	int mode = ctxt->mode;
-	int def_op_bytes, def_ad_bytes, group;
+	int def_op_bytes, def_ad_bytes, group, dual;
 
 
 	/* we cannot decode insn before we complete previous rep insn */
@@ -1055,14 +1055,16 @@ done_prefixes:
 
 	if (c->d & Group) {
 		group = c->d & GroupMask;
+		dual = c->d & GroupDual;
 		c->modrm = insn_fetch(u8, 1, c->eip);
 		--c->eip;
 
 		group = (group << 3) + ((c->modrm >> 3) & 7);
-		if ((c->d & GroupDual) && (c->modrm >> 6) == 3)
-			c->d = group2_table[group];
+		c->d &= ~(Group | GroupDual | GroupMask);
+		if (dual && (c->modrm >> 6) == 3)
+			c->d |= group2_table[group];
 		else
-			c->d = group_table[group];
+			c->d |= group_table[group];
 	}
 
 	/* Unrecognised? */
-- 
1.7.1