[PATCH] x86/hyperv: Disable preemption while setting reenlightenment vector

Vitaly Kuznetsov vkuznets at redhat.com
Fri Jun 14 21:44:36 UTC 2019


Peter Zijlstra <peterz at infradead.org> writes:

>
> I know you probably can't change the HV interface, but I'm thinking its
> rather daft you have to specify a CPU at all for this. The HV can just
> pick one and send the notification there, who cares.

Generally speaking, hypervisor can't know if the CPU is offline (or
e.g. 'isolated') from guest's perspective so I think having an option to
specify affinity for reenlightenment notification is rather a good
thing, not bad.

(Actually, I don't remember if I tried specifying 'HV_ANY' (U32_MAX-1)
here to see what happens. But then I doubt it'll notice the fact that we 
offlined some CPU so we may get a totally unexpected IRQ there).

-- 
Vitaly


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