KVM: PIT: control word is write-only

PIT control word (address 0x43) is write-only, reads are undefined. Cc: stable@kernel.org Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
git-mirror · Feb 9, 2010 · ee73f65 · ee73f65
1 parent 923de3c
commit ee73f65
Showing 1 changed file with 3 additions and 0 deletions.
diff --git 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);