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Commit 1ce19dc1 authored by Borislav Petkov's avatar Borislav Petkov Committed by Paolo Bonzini
Browse files

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: default avatarBorislav Petkov <bp@suse.de>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 9c15bb1d

arch/x86/include/asm/kvm_emulate.h

+6 −2
Original line number Diff line number Diff line
@@ -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;

arch/x86/kvm/emulate.c

+3 −2
Original line number Diff line number Diff line
@@ -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 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len) 
	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 @@ int x86_emulate_insn(struct x86_emulate_ctxt *ctxt) 
		goto writeback;

	}



	if (ctxt->twobyte)

	if (ctxt->opcode_len == 2)

		goto twobyte_insn;



	switch (ctxt->b) {

arch/x86/kvm/x86.c

+2 −2
Original line number Diff line number Diff line
@@ -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;