KVM: PIT: control word is write-only

Commit Message

Marcelo Tosatti Jan. 29, 2010, 7:28 p.m. UTC

None

Patch

diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index caad189..6a74246 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -467,6 +467,9 @@  static int pit_ioport_read(struct kvm_io_device *this,
 		return -EOPNOTSUPP;
 
 	addr &= KVM_PIT_CHANNEL_MASK;
+	if (addr == 3)
+		return 0;
+
 	s = &pit_state->channels[addr];
 
 	mutex_lock(&pit_state->lock);