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Commit b3356bf0 authored by Gleb Natapov's avatar Gleb Natapov Committed by Avi Kivity
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KVM: emulator: optimize "rep ins" handling 



Optimize "rep ins" by allowing emulator to write back more than one
datum at a time. Introduce new operand type OP_MEM_STR which tells
writeback() that dst contains pointer to an array that should be written
back as opposite to just one data element.

Signed-off-by: default avatarGleb Natapov <gleb@redhat.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent f3bd64c6

arch/x86/include/asm/kvm_emulate.h

+3 −1
Original line number Diff line number Diff line
@@ -213,8 +213,9 @@ typedef u32 __attribute__((vector_size(16))) sse128_t; 


/* Type, address-of, and value of an instruction's operand. */

struct operand {

	enum { OP_REG, OP_MEM, OP_IMM, OP_XMM, OP_MM, OP_NONE } type;

	enum { OP_REG, OP_MEM, OP_MEM_STR, OP_IMM, OP_XMM, OP_MM, OP_NONE } type;

	unsigned int bytes;

	unsigned int count;

	union {

		unsigned long orig_val;

		u64 orig_val64;
@@ -234,6 +235,7 @@ struct operand { 
		char valptr[sizeof(unsigned long) + 2];

		sse128_t vec_val;

		u64 mm_val;

		void *data;

	};

};

arch/x86/kvm/emulate.c

+28 −5
Original line number Diff line number Diff line
@@ -1301,8 +1301,15 @@ static int pio_in_emulated(struct x86_emulate_ctxt *ctxt, 
		rc->end = n * size;

	}



	if (ctxt->rep_prefix && !(ctxt->eflags & EFLG_DF)) {

		ctxt->dst.data = rc->data + rc->pos;

		ctxt->dst.type = OP_MEM_STR;

		ctxt->dst.count = (rc->end - rc->pos) / size;

		rc->pos = rc->end;

	} else {

		memcpy(dest, rc->data + rc->pos, size);

		rc->pos += size;

	}

	return 1;

}
@@ -1546,6 +1553,14 @@ static int writeback(struct x86_emulate_ctxt *ctxt) 
		if (rc != X86EMUL_CONTINUE)

			return rc;

		break;

	case OP_MEM_STR:

		rc = segmented_write(ctxt,

				ctxt->dst.addr.mem,

				ctxt->dst.data,

				ctxt->dst.bytes * ctxt->dst.count);

		if (rc != X86EMUL_CONTINUE)

			return rc;

		break;

	case OP_XMM:

		write_sse_reg(ctxt, &ctxt->dst.vec_val, ctxt->dst.addr.xmm);

		break;
@@ -2793,7 +2808,7 @@ int emulator_task_switch(struct x86_emulate_ctxt *ctxt, 
static void string_addr_inc(struct x86_emulate_ctxt *ctxt, int reg,

		struct operand *op)

{

	int df = (ctxt->eflags & EFLG_DF) ? -1 : 1;

	int df = (ctxt->eflags & EFLG_DF) ? -op->count : op->count;



	register_address_increment(ctxt, reg_rmw(ctxt, reg), df * op->bytes);

	op->addr.mem.ea = register_address(ctxt, reg_read(ctxt, reg));
@@ -3733,7 +3748,7 @@ static const struct opcode opcode_table[256] = { 
	I(DstReg | SrcMem | ModRM | Src2Imm, em_imul_3op),

	I(SrcImmByte | Mov | Stack, em_push),

	I(DstReg | SrcMem | ModRM | Src2ImmByte, em_imul_3op),

	I2bvIP(DstDI | SrcDX | Mov | String, em_in, ins, check_perm_in), /* insb, insw/insd */

	I2bvIP(DstDI | SrcDX | Mov | String | Unaligned, em_in, ins, check_perm_in), /* insb, insw/insd */

	I2bvIP(SrcSI | DstDX | String, em_out, outs, check_perm_out), /* outsb, outsw/outsd */

	/* 0x70 - 0x7F */

	X16(D(SrcImmByte)),
@@ -3991,6 +4006,7 @@ static int decode_operand(struct x86_emulate_ctxt *ctxt, struct operand *op, 
			register_address(ctxt, reg_read(ctxt, VCPU_REGS_RDI));

		op->addr.mem.seg = VCPU_SREG_ES;

		op->val = 0;

		op->count = 1;

		break;

	case OpDX:

		op->type = OP_REG;
@@ -4034,6 +4050,7 @@ static int decode_operand(struct x86_emulate_ctxt *ctxt, struct operand *op, 
			register_address(ctxt, reg_read(ctxt, VCPU_REGS_RSI));

		op->addr.mem.seg = seg_override(ctxt);

		op->val = 0;

		op->count = 1;

		break;

	case OpImmFAddr:

		op->type = OP_IMM;
@@ -4575,8 +4592,14 @@ writeback: 
		string_addr_inc(ctxt, VCPU_REGS_RDI, &ctxt->dst);



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

		unsigned int count;

		struct read_cache *r = &ctxt->io_read;

		register_address_increment(ctxt, reg_rmw(ctxt, VCPU_REGS_RCX), -1);

		if ((ctxt->d & SrcMask) == SrcSI)

			count = ctxt->src.count;

		else

			count = ctxt->dst.count;

		register_address_increment(ctxt, reg_rmw(ctxt, VCPU_REGS_RCX),

				-count);



		if (!string_insn_completed(ctxt)) {

			/*