Messages in this thread |  | | Subject | Re: [PATCH v6 13/18] KVM: arm64: Support SDEI_EVENT_{COMPLETE,COMPLETE_AND_RESUME} hypercall | From | Gavin Shan <> | Date | Mon, 2 May 2022 14:19:30 +0800 |
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Hi Oliver,
On 5/1/22 2:50 PM, Oliver Upton wrote: > On Sun, Apr 03, 2022 at 11:39:06PM +0800, Gavin Shan wrote: >> This supports SDEI_EVENT_{COMPLETE, COMPLETE_AND_RESUME} hypercall. >> They are used by guest to notify the completion of event in its >> handler. The previously interrupted or preempted context is restored >> like below. >> >> * x0 - x17, PC and PState are restored to what values we had in >> the interrupted or preempted context. >> >> * If it's SDEI_EVENT_COMPLETE_AND_RESUME hypercall, IRQ exception >> is injected. > > I don't think that's how COMPLETE_AND_RESUME works. The caller specifies an > address at which it would like to begin execution within the client > exception level. > > SDEI spec suggests this behaves like a synchronous exception. DEN 0054C > 5.2.2 'Event Resume Context' speaks more about how it is supposed to > work. >
It's actually the linux convention. If the event handler, which was specified in previous hypercall to EVENT_REGISTER, returns success, the (linux) client calls into COMPLETE_AND_RESUME and the resume address is specified with FIQ vector offset. More details can be found from arch/arm64/kernel::sdei.c::do_sdei_event().
Thanks, Gavin
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