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: Gleb Natapov <gleb@xxxxxxxxxx>
---
arch/x86/include/asm/kvm_emulate.h | 4 +++-
arch/x86/kvm/emulate.c | 33 ++++++++++++++++++++++++++++-----
2 files changed, 31 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index 8d0fe8f..d1777f8 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -200,8 +200,9 @@ 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;
@@ -221,6 +222,7 @@ struct operand {
char valptr[sizeof(unsigned long) + 2];
sse128_t vec_val;
u64 mm_val;
+ void *data;
};
};
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index c22762d..c74bce8 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1251,8 +1251,15 @@ static int pio_in_emulated(struct x86_emulate_ctxt *ctxt,
rc->end = n * size;
}
- memcpy(dest, rc->data + rc->pos, size);
- rc->pos += 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;
}
@@ -1500,6 +1507,14 @@ 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;
@@ -2732,7 +2747,7 @@ 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, &ctxt->regs[reg], df * op->bytes);
op->addr.mem.ea = register_address(ctxt, ctxt->regs[reg]);
@@ -3672,7 +3687,7 @@ static 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)),
@@ -3930,6 +3945,7 @@ static int decode_operand(struct x86_emulate_ctxt *ctxt, struct operand *op,
register_address(ctxt, ctxt->regs[VCPU_REGS_RDI]);
op->addr.mem.seg = VCPU_SREG_ES;
op->val = 0;
+ op->count = 1;
break;
case OpDX:
op->type = OP_REG;
@@ -3973,6 +3989,7 @@ static int decode_operand(struct x86_emulate_ctxt *ctxt, struct operand *op,
register_address(ctxt, ctxt->regs[VCPU_REGS_RSI]);
op->addr.mem.seg = seg_override(ctxt);
op->val = 0;
+ op->count = 1;
break;
case OpImmFAddr:
op->type = OP_IMM;
@@ -4513,8 +4530,14 @@ 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, &ctxt->regs[VCPU_REGS_RCX], -1);
+ if ((ctxt->d & SrcMask) == SrcSI)
+ count = ctxt->src.count;
+ else
+ count = ctxt->dst.count;
+ register_address_increment(ctxt, &ctxt->regs[VCPU_REGS_RCX],
+ -count);
if (!string_insn_completed(ctxt)) {
/*
--
1.7.10
--
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