Commit b9fa9d6b authored by Avi Kivity's avatar Avi Kivity
Browse files

KVM: x86 emulator: Move rep processing before instruction execution 



Currently rep processing is handled somewhere in the middle of instruction
processing.  Move it to a sensible place.

Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent 51e29625

drivers/kvm/x86_emulate.c

+36 −34
Original line number Diff line number Diff line
@@ -64,6 +64,7 @@ 
#define Mov         (1<<7)

#define BitOp       (1<<8)

#define MemAbs      (1<<9)      /* Memory operand is absolute displacement */

#define String      (1<<10)     /* String instruction (rep capable) */



static u16 opcode_table[256] = {

	/* 0x00 - 0x07 */
@@ -133,12 +134,12 @@ static u16 opcode_table[256] = { 
	/* 0xA0 - 0xA7 */

	ByteOp | DstReg | SrcMem | Mov | MemAbs, DstReg | SrcMem | Mov | MemAbs,

	ByteOp | DstMem | SrcReg | Mov | MemAbs, DstMem | SrcReg | Mov | MemAbs,

	ByteOp | ImplicitOps | Mov, ImplicitOps | Mov,

	ByteOp | ImplicitOps, ImplicitOps,

	ByteOp | ImplicitOps | Mov | String, ImplicitOps | Mov | String,

	ByteOp | ImplicitOps | String, ImplicitOps | String,

	/* 0xA8 - 0xAF */

	0, 0, ByteOp | ImplicitOps | Mov, ImplicitOps | Mov,

	ByteOp | ImplicitOps | Mov, ImplicitOps | Mov,

	ByteOp | ImplicitOps, ImplicitOps,

	0, 0, ByteOp | ImplicitOps | Mov | String, ImplicitOps | Mov | String,

	ByteOp | ImplicitOps | Mov | String, ImplicitOps | Mov | String,

	ByteOp | ImplicitOps | String, ImplicitOps | String,

	/* 0xB0 - 0xBF */

	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,

	/* 0xC0 - 0xC7 */
@@ -1228,6 +1229,36 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops) 
	if (((c->d & ModRM) && (c->modrm_mod != 3)) || (c->d & MemAbs))

		memop = c->modrm_ea;



	if (c->rep_prefix && (c->d & String)) {

		/* 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;

	}



	if (c->src.type == OP_MEM) {

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

		c->src.val = 0;
@@ -1534,35 +1565,6 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops) 
		c->dst.type = OP_NONE;	/* Disable writeback. */

		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;

	}

	switch (c->b) {

	case 0xa4 ... 0xa5:	/* movs */

		c->dst.type = OP_MEM;