From: Paolo Bonzini <pbonzini@redhat.com>
To: Gavin Shan <gshan@redhat.com>, James Morse <james.morse@arm.com>
Cc: mark.rutland@arm.com, maz@kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [Question] How to testing SDEI client driver
Date: Fri, 10 Jul 2020 11:38:12 +0200 [thread overview]
Message-ID: <098f56da-bcb9-42e6-10cc-f1df90f28ec1@redhat.com> (raw)
In-Reply-To: <0698199d-c84c-c923-e665-e09d5b83ba66@redhat.com>
On 10/07/20 11:08, Gavin Shan wrote:
> Ok, thanks for the information, which makes thing much more clear.
> So SDEI_EVENT_COMPLETE/AND_RESUME is issued depending if current
> process can be rescheduled. I think it's Paolo's idea?
Yes. :)
>> The problem is invoking this whole thing when the guest can't do
>> anything about it, because it can't schedule(). You can't know this
>> from outside the guest.
>
> Yes, the interrupted process can't call schedule() before
> SDEI_EVENT_COMPLETE at least because the SDEI event handler has to
> finish as quick as possible.
>
> [...] we might figure out one
> way to insert the schedule() by the SDEI event handler.
I think you could do smp_send_reschedule(smp_processor_id()) before
invoking SDEI_EVENT_COMPLETE_AND_RESUME. As James said, after the
hypervisor processes SDEI_EVENT_COMPLETE_AND_RESUME the exit will be
through the reschedule interrupt.
Instead if the hypervisor sees SDEI_EVENT_COMPLETE it will wait for
synchronous page-in to complete, remove the async page fault from its
data structures, and resume execution.
Paolo
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next prev parent reply other threads:[~2020-07-10 9:39 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-30 5:17 [Question] How to testing SDEI client driver Gavin Shan
2020-07-01 11:57 ` James Morse
2020-07-03 0:26 ` Gavin Shan
2020-07-08 16:11 ` James Morse
2020-07-08 16:49 ` Paolo Bonzini
2020-07-09 5:33 ` Gavin Shan
2020-07-09 18:31 ` James Morse
2020-07-10 9:08 ` Gavin Shan
2020-07-10 9:38 ` Paolo Bonzini [this message]
2020-07-09 18:30 ` James Morse
2020-07-09 18:50 ` Paolo Bonzini
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