Re: [PATCH] s390/vfio-ap: handle response code 01 on queue reset
From: Tony Krowiak
Date: Mon Dec 04 2023 - 12:05:34 EST
On 12/4/23 11:15, Halil Pasic wrote:
On Mon, 4 Dec 2023 16:16:31 +0100
Christian Borntraeger <borntraeger@xxxxxxxxxxxxx> wrote:
Am 04.12.23 um 15:53 schrieb Tony Krowiak:
On 11/29/23 12:12, Christian Borntraeger wrote:
Am 29.11.23 um 15:35 schrieb Tony Krowiak:
In the current implementation, response code 01 (AP queue number not valid)
is handled as a default case along with other response codes returned from
a queue reset operation that are not handled specifically. Barring a bug,
response code 01 will occur only when a queue has been externally removed
from the host's AP configuration; nn this case, the queue must
be reset by the machine in order to avoid leaking crypto data if/when the
queue is returned to the host's configuration. The response code 01 case
will be handled specifically by logging a WARN message followed by cleaning
up the IRQ resources.
To me it looks like this can be triggered by the LPAR admin, correct? So it
is not desireable but possible.
In that case I prefer to not use WARN, maybe use dev_warn or dev_err instead.
WARN can be a disruptive event if panic_on_warn is set.
Yes, it can be triggered by the LPAR admin. I can't use dev_warn here because we don't have a reference to any device, but I can use pr_warn if that suffices.
Ok, please use pr_warn then.
Shouldn't we rather make this an 'info'. I mean we probably do not want
people complaining about this condition. Yes it should be a best practice
to coordinate such things with the guest, and ideally remove the resource
from the guest first. But AFAIU our stack is supposed to be able to
handle something like this. IMHO issuing a warning is excessive measure.
I know Reinhard and Tony probably disagree with the last sentence
though.
I don't feel strongly one way or the other. Anybody else?
Regards,
Halil