From 9f4260e73ac43aaa91eb5de95950e1de7002f467 Mon Sep 17 00:00:00 2001 From: Takuya Yoshikawa Date: Mon, 30 Apr 2012 17:48:25 +0900 Subject: [PATCH] KVM: x86 emulator: Avoid pushing back ModRM byte fetched for group decoding Although ModRM byte is fetched for group decoding, it is soon pushed back to make decode_modrm() fetch it later again. Now that ModRM flag can be found in the top level opcode tables, fetch ModRM byte before group decoding to make the code simpler. Signed-off-by: Takuya Yoshikawa Signed-off-by: Avi Kivity --- arch/x86/kvm/emulate.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 8d2c3d04cfec..7fd25763b0e0 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -972,7 +972,6 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt, ctxt->modrm_rm = base_reg = (ctxt->rex_prefix & 1) << 3; /* REG.B */ } - ctxt->modrm = insn_fetch(u8, ctxt); ctxt->modrm_mod |= (ctxt->modrm & 0xc0) >> 6; ctxt->modrm_reg |= (ctxt->modrm & 0x38) >> 3; ctxt->modrm_rm |= (ctxt->modrm & 0x07); @@ -3976,17 +3975,16 @@ done_prefixes: } ctxt->d = opcode.flags; + if (ctxt->d & ModRM) + ctxt->modrm = insn_fetch(u8, ctxt); + while (ctxt->d & GroupMask) { switch (ctxt->d & GroupMask) { case Group: - ctxt->modrm = insn_fetch(u8, ctxt); - --ctxt->_eip; goffset = (ctxt->modrm >> 3) & 7; opcode = opcode.u.group[goffset]; break; case GroupDual: - ctxt->modrm = insn_fetch(u8, ctxt); - --ctxt->_eip; goffset = (ctxt->modrm >> 3) & 7; if ((ctxt->modrm >> 6) == 3) opcode = opcode.u.gdual->mod3[goffset]; -- 2.34.1