From 1ce19dc16ce9136cccb6087e4a383ec9321980d9 Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Sun, 22 Sep 2013 16:44:51 +0200 Subject: [PATCH] kvm, emulator: Use opcode length Add a field to the current emulation context which contains the instruction opcode length. This will streamline handling of opcodes of different length. Signed-off-by: Borislav Petkov Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm_emulate.h | 8 ++++++-- arch/x86/kvm/emulate.c | 5 +++-- arch/x86/kvm/x86.c | 4 ++-- 3 files changed, 11 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h index 15f960c06ff7..92a176ad456c 100644 --- a/arch/x86/include/asm/kvm_emulate.h +++ b/arch/x86/include/asm/kvm_emulate.h @@ -279,8 +279,12 @@ struct x86_emulate_ctxt { bool have_exception; struct x86_exception exception; - /* decode cache */ - u8 twobyte; + /* + * decode cache + */ + + /* current opcode length in bytes */ + u8 opcode_len; u8 b; u8 intercept; u8 lock_prefix; diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index ddc3f3d2afdb..d554d96afbca 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -4126,6 +4126,7 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len) ctxt->_eip = ctxt->eip; ctxt->fetch.start = ctxt->_eip; ctxt->fetch.end = ctxt->fetch.start + insn_len; + ctxt->opcode_len = 1; if (insn_len > 0) memcpy(ctxt->fetch.data, insn, insn_len); @@ -4208,7 +4209,7 @@ done_prefixes: opcode = opcode_table[ctxt->b]; /* Two-byte opcode? */ if (ctxt->b == 0x0f) { - ctxt->twobyte = 1; + ctxt->opcode_len = 2; ctxt->b = insn_fetch(u8, ctxt); opcode = twobyte_table[ctxt->b]; } @@ -4540,7 +4541,7 @@ special_insn: goto writeback; } - if (ctxt->twobyte) + if (ctxt->opcode_len == 2) goto twobyte_insn; switch (ctxt->b) { diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 3d1e3ee8b39e..d00d88455fef 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4789,8 +4789,8 @@ static void inject_emulated_exception(struct kvm_vcpu *vcpu) static void init_decode_cache(struct x86_emulate_ctxt *ctxt) { - memset(&ctxt->twobyte, 0, - (void *)&ctxt->_regs - (void *)&ctxt->twobyte); + memset(&ctxt->opcode_len, 0, + (void *)&ctxt->_regs - (void *)&ctxt->opcode_len); ctxt->fetch.start = 0; ctxt->fetch.end = 0; -- 2.11.0