On Wed, 14 Dec 2011, Avi Kivity wrote: > On 12/14/2011 07:11 PM, Eric B Munson wrote: > > > > > > > > > > If I understand (please correct me if this is wrong) because this is only > > > > > called from the watchdog, which disables preemption, we should be protected > > > > > from something else writing to these flags. > > > > > > > > The host can write, but in that case race is harmless. > > > > > > Why is it harmless? You don't know what's in those other flags. > > > > > > -- > > > error compiling committee.c: too many arguments to function > > > > > > > Currently there is only one other flag in this byte (PVCLOCK_TSC_STABLE_BIT) > > and it isset once in kvmclock_init(). It is highly unlikely that the vm will > > be stopped during this init and have the flag clobbered. After the tsc stable > > bit is written in the init, the field is read only outside of the guest paused > > code. > > Let's not lay minefields for us later to step into. Making this a > cpu-local atomic (irq safe but not smp safe) is simple and easy, > somehting like __this_cpu_and(). > > -- > error compiling committee.c: too many arguments to function > Fair enough, I will add this to V7.
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