KVM: x86 emulator: check io permissions only once for string pio

Do not recheck io permission on every iteration.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 3cbe803..35c0f4e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3997,6 +3997,7 @@
 		memcpy(c->regs, vcpu->arch.regs, sizeof c->regs);
 		vcpu->arch.emulate_ctxt.interruptibility = 0;
 		vcpu->arch.emulate_ctxt.exception = -1;
+		vcpu->arch.emulate_ctxt.perm_ok = false;
 
 		r = x86_decode_insn(&vcpu->arch.emulate_ctxt);
 		trace_kvm_emulate_insn_start(vcpu);