linux-kernel - Re: [PATCH v3 2/3] s390/vfio-ap: set status response code to 06 on gisc registration failure

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Date:   Fri, 27 Oct 2023 13:19:04 +0200
From:   Halil Pasic <pasic@...ux.ibm.com>
To:     Tony Krowiak <akrowiak@...ux.ibm.com>
Cc:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, jjherne@...ux.ibm.com,
        borntraeger@...ux.ibm.com, frankja@...ux.ibm.com,
        imbrenda@...ux.ibm.com, david@...hat.com, mjrosato@...ux.ibm.com,
        Halil Pasic <pasic@...ux.ibm.com>
Subject: Re: [PATCH v3 2/3] s390/vfio-ap: set status response code to 06 on
 gisc registration failure

On Thu, 26 Oct 2023 14:32:44 -0400
Tony Krowiak <akrowiak@...ux.ibm.com> wrote:

> Since this scenario is very unlikely to happen and there is no status
> response code to indicate an invalid ISC value, let's set the

Again invalid ISC won't happen except for hypervisor messes up.

> response code to 06 indicating 'Invalid address of AP-queue notification
> byte'. While this is not entirely accurate, it is better than indicating
> that the ZONE/GISA designation is invalid which is something the guest
> can do nothing about since those values are set by the hypervisor.

And more importantly AP_RESPONSE_INVALID_GISA is not valid for G2 in
the given scenario, since G2 is not trying to set up interrupts on behalf
of the G3 with a G3 GISA, but G2 is trying to set up interrupts for
itself. And then AP_RESPONSE_INVALID_GISA is architecturally simply not
a valid RC!

> 
> Signed-off-by: Anthony Krowiak <akrowiak@...ux.ibm.com>
> Suggested-by: Halil Pasic <pasic@...ux.ibm.com>

Except for the explanation in the commit message, the patch is good. It
is up to you if you want to fix the commit message or not.

Reviewed-by: Halil Pasic <pasic@...ux.ibm.com>