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/emulate.c b/arch/x86/kvm/emulate.c
index 4d49514..760e2b0 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1621,9 +1621,15 @@
struct x86_emulate_ops *ops,
u16 port, u16 len)
{
+ if (ctxt->perm_ok)
+ return true;
+
if (emulator_bad_iopl(ctxt, ops))
if (!emulator_io_port_access_allowed(ctxt, ops, port, len))
return false;
+
+ ctxt->perm_ok = true;
+
return true;
}