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@xxxxxxxxxx>
> ---
> 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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