linux-kernel - Re: [PATCH v6 13/18] KVM: arm64: Support SDEI_EVENT_{COMPLETE,COMPLETE_AND

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Message-ID: <Ym4tzRL0iMxyumJe@google.com>
Date:   Sun, 1 May 2022 06:50:53 +0000
From:   Oliver Upton <oupton@...gle.com>
To:     Gavin Shan <gshan@...hat.com>
Cc:     kvmarm@...ts.cs.columbia.edu, linux-kernel@...r.kernel.org,
        eauger@...hat.com, Jonathan.Cameron@...wei.com,
        vkuznets@...hat.com, will@...nel.org, shannon.zhaosl@...il.com,
        james.morse@....com, mark.rutland@....com, maz@...nel.org,
        pbonzini@...hat.com, shan.gavin@...il.com
Subject: Re: [PATCH v6 13/18] KVM: arm64: Support
 SDEI_EVENT_{COMPLETE,COMPLETE_AND_RESUME} hypercall

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.

--
Thanks,
Oliver