3.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Igor Mammedov <imammedo@xxxxxxxxxx>
commit 07868fc6aaf57847b0f3a3d53086b7556eb83f4a upstream.
kernel might hung in pvclock_clocksource_read() due to
uninitialized memory might contain odd version value in
following cycle:
do {
version = __pvclock_read_cycles(src, &ret, &flags);
} while ((src->version & 1) || version != src->version);
if secondary kvmclock is accessed before it's registered with kvm.
Clear garbage in pvclock shared memory area right after it's
allocated to avoid this issue.
Ref: https://bugzilla.kernel.org/show_bug.cgi?id=59521
Signed-off-by: Igor Mammedov <imammedo@xxxxxxxxxx>
[See BZ for analysis. We may want a different fix for 3.11, but
this is the safest for now - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/kvmclock.c | 1 +
1 file changed, 1 insertion(+)
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -238,6 +238,7 @@ void __init kvmclock_init(void)
if (!mem)
return;
hv_clock = __va(mem);
+ memset(hv_clock, 0, size);
if (kvm_register_clock("boot clock")) {
hv_clock = NULL;
--
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