Re: [KVM timekeeping 03/35] Move TSC offset writes to common code

[Glauber Costa]

On Thu, Aug 19, 2010 at 10:07:17PM -1000, Zachary Amsden wrote:
> Also, ensure that the storing of the offset and the reading of the TSC
> are never preempted by taking a spinlock.  While the lock is overkill
> now, it is useful later in this patch series.
> 
> +	spinlock_t tsc_write_lock;
Forgive my utter ignorance, specially if it is to become
obvious in a latter patch: This is a vcpu-local operation,
uses rdtscl, so pcpu-local too, and we don't expect
multiple writers to it at the same time.

Why do we need this lock?

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