Commit 07868fc6 authored by Igor Mammedov's avatar Igor Mammedov Committed by Paolo Bonzini

x86: kvmclock: zero initialize pvclock shared memory area

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=59521Signed-off-by: default avatarIgor Mammedov <imammedo@redhat.com>
[See BZ for analysis.  We may want a different fix for 3.11, but
 this is the safest for now - Paolo]
Cc: <stable@vger.kernel.org> # 3.8
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent f8941fbe
......@@ -242,6 +242,7 @@ 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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