Commit d7e5117a authored by Guillaume Thouvenin's avatar Guillaume Thouvenin Committed by Avi Kivity
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KVM: x86 emulator: cmps instruction 



Add emulation for the cmps instruction.  This lets OpenBSD boot on kvm.

Signed-off-by: default avatarGuillaume Thouvenin <guillaume.thouvenin@ext.bull.net>
Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent e8d8d7fe

drivers/kvm/x86_emulate.c

+56 −2
Original line number Diff line number Diff line
@@ -1535,10 +1535,31 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops) 
		break;

	}

	if (c->rep_prefix) {

		/* All REP prefixes have the same first termination condition */

		if (c->regs[VCPU_REGS_RCX] == 0) {

			ctxt->vcpu->rip = c->eip;

			goto done;

		}

		/* The second termination condition only applies for REPE

		 * and REPNE. Test if the repeat string operation prefix is

		 * REPE/REPZ or REPNE/REPNZ and if it's the case it tests the

		 * corresponding termination condition according to:

		 * 	- if REPE/REPZ and ZF = 0 then done

		 * 	- if REPNE/REPNZ and ZF = 1 then done

		 */

		if ((c->b == 0xa6) || (c->b == 0xa7) ||

				(c->b == 0xae) || (c->b == 0xaf)) {

			if ((c->rep_prefix == REPE_PREFIX) &&

				((ctxt->eflags & EFLG_ZF) == 0)) {

					ctxt->vcpu->rip = c->eip;

					goto done;

			}

			if ((c->rep_prefix == REPNE_PREFIX) &&

				((ctxt->eflags & EFLG_ZF) == EFLG_ZF)) {

				ctxt->vcpu->rip = c->eip;

				goto done;

			}

		}

		c->regs[VCPU_REGS_RCX]--;

		c->eip = ctxt->vcpu->rip;

	}
@@ -1564,8 +1585,41 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops) 
							   : c->dst.bytes);

		break;

	case 0xa6 ... 0xa7:	/* cmps */

		DPRINTF("Urk! I don't handle CMPS.\n");

		goto cannot_emulate;

		c->src.type = OP_NONE; /* Disable writeback. */

		c->src.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;

		c->src.ptr = (unsigned long *)register_address(

				c->override_base ? *c->override_base :

						   ctxt->ds_base,

						   c->regs[VCPU_REGS_RSI]);

		if ((rc = ops->read_emulated((unsigned long)c->src.ptr,

						&c->src.val,

						c->src.bytes,

						ctxt->vcpu)) != 0)

			goto done;



		c->dst.type = OP_NONE; /* Disable writeback. */

		c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;

		c->dst.ptr = (unsigned long *)register_address(

						   ctxt->es_base,

						   c->regs[VCPU_REGS_RDI]);

		if ((rc = ops->read_emulated((unsigned long)c->dst.ptr,

						&c->dst.val,

						c->dst.bytes,

						ctxt->vcpu)) != 0)

			goto done;



		DPRINTF("cmps: mem1=0x%p mem2=0x%p\n", c->src.ptr, c->dst.ptr);



		emulate_2op_SrcV("cmp", c->src, c->dst, ctxt->eflags);



		register_address_increment(c->regs[VCPU_REGS_RSI],

				       (ctxt->eflags & EFLG_DF) ? -c->src.bytes

								  : c->src.bytes);

		register_address_increment(c->regs[VCPU_REGS_RDI],

				       (ctxt->eflags & EFLG_DF) ? -c->dst.bytes

								  : c->dst.bytes);



		break;

	case 0xaa ... 0xab:	/* stos */

		c->dst.type = OP_MEM;

		c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;