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 <yoshikawa.takuya@oss.ntt.co.jp> Signed-off-by: Avi Kivity <avi@redhat.com>
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@ -972,7 +972,6 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
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ctxt->modrm_rm = base_reg = (ctxt->rex_prefix & 1) << 3; /* REG.B */
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}
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ctxt->modrm = insn_fetch(u8, ctxt);
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ctxt->modrm_mod |= (ctxt->modrm & 0xc0) >> 6;
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ctxt->modrm_reg |= (ctxt->modrm & 0x38) >> 3;
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ctxt->modrm_rm |= (ctxt->modrm & 0x07);
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@ -3976,17 +3975,16 @@ done_prefixes:
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}
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ctxt->d = opcode.flags;
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if (ctxt->d & ModRM)
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ctxt->modrm = insn_fetch(u8, ctxt);
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while (ctxt->d & GroupMask) {
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switch (ctxt->d & GroupMask) {
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case Group:
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ctxt->modrm = insn_fetch(u8, ctxt);
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--ctxt->_eip;
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goffset = (ctxt->modrm >> 3) & 7;
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opcode = opcode.u.group[goffset];
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break;
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case GroupDual:
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ctxt->modrm = insn_fetch(u8, ctxt);
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--ctxt->_eip;
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goffset = (ctxt->modrm >> 3) & 7;
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if ((ctxt->modrm >> 6) == 3)
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opcode = opcode.u.gdual->mod3[goffset];
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