Xen (and others Hypervisors) how do they handle IPIs?
Julian Elischer
julian at freebsd.org
Thu Sep 26 14:51:32 UTC 2013
On 9/26/13 4:16 PM, Peter Grehan wrote:
> Hi Julian,
>
>> If CPUs are mapped around, how are IPIs handled? I assume they must be
>> emulated?
>
> For bhyve, if the target vCPU of an IPI is running, a null IPI is
> sent on the host to force it to exit so the IPI can be injected
> (vmm.c:vm_interrupt_hostcpu()).
>
> If the target is asleep due to being idle, it is woken up. And, if
> the target is running but not in vCPU context, an interrupt is
> queued up so it will be injected on the next vmenter (subject to the
> emulated local APIC interrupt priority)
>
>> Does anyone know if BHyVe or HyperV also have this problem?
>
> Hmmm, hard to say. Would you be able to try your workload out on a
> bhyve system ?
possibly in a few weeks.. I'll try remember when the time is right.
>
> later,
>
> Peter.
>
>
>
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