To optimize "rep ins" instruction do IO in big chunks ahead of time instead of doing it only when required during instruction emulation.
Signed-off-by: Gleb Natapov <[email protected]> --- arch/x86/include/asm/kvm_emulate.h | 7 ++++++ arch/x86/kvm/emulate.c | 43 +++++++++++++++++++++++++++++++---- 2 files changed, 45 insertions(+), 5 deletions(-) diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h index 7fda16f..b5e12c5 100644 --- a/arch/x86/include/asm/kvm_emulate.h +++ b/arch/x86/include/asm/kvm_emulate.h @@ -151,6 +151,12 @@ struct fetch_cache { unsigned long end; }; +struct read_cache { + u8 data[1024]; + unsigned long pos; + unsigned long end; +}; + struct decode_cache { u8 twobyte; u8 b; @@ -178,6 +184,7 @@ struct decode_cache { void *modrm_ptr; unsigned long modrm_val; struct fetch_cache fetch; + struct read_cache io_read; }; struct x86_emulate_ctxt { diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index c4da60e..d9cf93b 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -1257,6 +1257,34 @@ done: return (rc == X86EMUL_UNHANDLEABLE) ? -1 : 0; } +static int pio_in_emulated(struct x86_emulate_ctxt *ctxt, + struct x86_emulate_ops *ops, + unsigned int size, unsigned short port, + void *dest) +{ + struct read_cache *rc = &ctxt->decode.io_read; + + if (rc->pos == rc->end) { /* refill pio read ahead */ + struct decode_cache *c = &ctxt->decode; + unsigned int in_page, n; + unsigned int count = c->rep_prefix ? + address_mask(c, c->regs[VCPU_REGS_RCX]) : 1; + in_page = (ctxt->eflags & EFLG_DF) ? + offset_in_page(c->regs[VCPU_REGS_RDI]) : + PAGE_SIZE - offset_in_page(c->regs[VCPU_REGS_RDI]); + n = min(min(in_page, (unsigned int)sizeof(rc->data)) / size, + count); + rc->pos = rc->end = 0; + if (!ops->pio_in_emulated(size, port, rc->data, n, ctxt->vcpu)) + return 0; + rc->end = n * size; + } + + memcpy(dest, rc->data + rc->pos, size); + rc->pos += size; + return 1; +} + static u32 desc_limit_scaled(struct desc_struct *desc) { u32 limit = get_desc_limit(desc); @@ -2618,8 +2646,8 @@ special_insn: kvm_inject_gp(ctxt->vcpu, 0); goto done; } - if (!ops->pio_in_emulated(c->dst.bytes, c->regs[VCPU_REGS_RDX], - &c->dst.val, 1, ctxt->vcpu)) + if (!pio_in_emulated(ctxt, ops, c->dst.bytes, + c->regs[VCPU_REGS_RDX], &c->dst.val)) goto done; /* IO is needed, skip writeback */ break; case 0x6e: /* outsb */ @@ -2835,8 +2863,7 @@ special_insn: kvm_inject_gp(ctxt->vcpu, 0); goto done; } - ops->pio_in_emulated(c->dst.bytes, c->src.val, &c->dst.val, 1, - ctxt->vcpu); + pio_in_emulated(ctxt, ops, c->dst.bytes, c->src.val, &c->dst.val); break; case 0xee: /* out al,dx */ case 0xef: /* out (e/r)ax,dx */ @@ -2923,8 +2950,14 @@ writeback: string_addr_inc(ctxt, es_base(ctxt), VCPU_REGS_RDI, &c->dst); if (c->rep_prefix && (c->d & String)) { + struct read_cache *rc = &ctxt->decode.io_read; register_address_increment(c, &c->regs[VCPU_REGS_RCX], -1); - if (!(c->regs[VCPU_REGS_RCX] & 0x3ff)) + /* + * Re-enter guest when pio read ahead buffer is empty or, + * if it is not used, after each 1024 iteration. + */ + if ((rc->end == 0 && !(c->regs[VCPU_REGS_RCX] & 0x3ff)) || + (rc->end != 0 && rc->end == rc->pos)) ctxt->restart = false; } -- 1.6.5 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
