Messages in this thread | | | Date | Mon, 10 Jun 2013 17:19:33 -0300 | From | Marcelo Tosatti <> | Subject | Re: [PATCH] x86: kvmclock: zero initialize pvclock shared memory area |
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On Mon, Jun 10, 2013 at 06:31:11PM +0200, Igor Mammedov wrote: > === > Could be the following an acceptable fix? > ===
Read of kvmclock should return proper value from hypervisor: system timestamp + tsc delta.
Should find the offender site and have it register MSR_KVM_SYSTEM_TIME before reading the 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=59521 > Signed-off-by: Igor Mammedov <imammedo@redhat.com> > --- > arch/x86/kernel/kvmclock.c | 1 + > 1 files changed, 1 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c > index d2c3812..3dd37eb 100644 > --- a/arch/x86/kernel/kvmclock.c > +++ b/arch/x86/kernel/kvmclock.c > @@ -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; > -- > 1.7.1
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