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Commit f21b8bf4 authored by Avi Kivity's avatar Avi Kivity
Browse files

KVM: x86 emulator: address size and operand size overrides are sticky 



Current implementation is to toggle, which is incorrect.  Patch ported from
corresponding Xen code.

Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent 90e0a28f

drivers/kvm/x86_emulate.c

+12 −7
Original line number Diff line number Diff line
@@ -758,6 +758,7 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops) 
	struct decode_cache *c = &ctxt->decode;

	int rc = 0;

	int mode = ctxt->mode;

	int def_op_bytes, def_ad_bytes;



	/* Shadow copy of register state. Committed on successful emulation. */
@@ -768,34 +769,38 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops) 
	switch (mode) {

	case X86EMUL_MODE_REAL:

	case X86EMUL_MODE_PROT16:

		c->op_bytes = c->ad_bytes = 2;

		def_op_bytes = def_ad_bytes = 2;

		break;

	case X86EMUL_MODE_PROT32:

		c->op_bytes = c->ad_bytes = 4;

		def_op_bytes = def_ad_bytes = 4;

		break;

#ifdef CONFIG_X86_64

	case X86EMUL_MODE_PROT64:

		c->op_bytes = 4;

		c->ad_bytes = 8;

		def_op_bytes = 4;

		def_ad_bytes = 8;

		break;

#endif

	default:

		return -1;

	}



	c->op_bytes = def_op_bytes;

	c->ad_bytes = def_ad_bytes;



	/* Legacy prefixes. */

	for (;;) {

		switch (c->b = insn_fetch(u8, 1, c->eip)) {

		case 0x66:	/* operand-size override */

			c->op_bytes ^= 6;	/* switch between 2/4 bytes */

			/* switch between 2/4 bytes */

			c->op_bytes = def_op_bytes ^ 6;

			break;

		case 0x67:	/* address-size override */

			if (mode == X86EMUL_MODE_PROT64)

				/* switch between 4/8 bytes */

				c->ad_bytes ^= 12;

				c->ad_bytes = def_ad_bytes ^ 12;

			else

				/* switch between 2/4 bytes */

				c->ad_bytes ^= 6;

				c->ad_bytes = def_ad_bytes ^ 6;

			break;

		case 0x2e:	/* CS override */

			c->override_base = &ctxt->cs_base;