Date: Thu, 26 Sep 2013 22:51:18 +0800 From: Julian Elischer <julian@freebsd.org> To: Peter Grehan <grehan@freebsd.org> Cc: virtualization@FreeBSD.org Subject: Re: Xen (and others Hypervisors) how do they handle IPIs? Message-ID: <524449E6.4050102@freebsd.org> In-Reply-To: <5243ED47.8080001@freebsd.org> References: <5242F9B8.9090300@freebsd.org> <5243ED47.8080001@freebsd.org>
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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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