[43/93] KVM: PIT: control word is write-only

From: Greg KH
Date: Fri Feb 19 2010 - 12:11:53 EST


2.6.32-stable review patch. If anyone has any objections, please let us know.

------------------

From: Marcelo Tosatti <mtosatti@xxxxxxxxxx>

commit ee73f656a604d5aa9df86a97102e4e462dd79924 upstream.

PIT control word (address 0x43) is write-only, reads are undefined.

Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
arch/x86/kvm/i8254.c | 3 +++
1 file changed, 3 insertions(+)

--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -465,6 +465,9 @@ static int pit_ioport_read(struct kvm_io
return -EOPNOTSUPP;

addr &= KVM_PIT_CHANNEL_MASK;
+ if (addr == 3)
+ return 0;
+
s = &pit_state->channels[addr];

mutex_lock(&pit_state->lock);


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