Re: [PATCH v9 17/22] s390: vfio-ap: zeroize the AP queues.

[Tony Krowiak]

On 08/15/2018 12:24 PM, Cornelia Huck wrote:
> On Mon, 13 Aug 2018 17:48:14 -0400
> Tony Krowiak <akrowiak@xxxxxxxxxxxxxxxxxx> wrote:
>
> Nit: please drop the leading period in the subject.

I assume you mean the ending period?

> > From: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
> >
> > Let's call PAPQ(ZAPQ) to zeroize a queue:
> >
> > * For each queue configured for a mediated matrix device
> >    when it is released.
> >
> > Zeroizing a queue resets the queue, clears all pending
> > messages for the queue entries and disables adapter interruptions
> > associated with the queue.
> >
> > Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
> > Reviewed-by: Halil Pasic <pasic@xxxxxxxxxxxxx>
> > Tested-by: Michael Mueller <mimu@xxxxxxxxxxxxx>
> > Tested-by: Farhan Ali <alifm@xxxxxxxxxxxxx>
> > Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
> > ---
> >   drivers/s390/crypto/vfio_ap_ops.c     |   25 +++++++++++++++++++++++++
> >   drivers/s390/crypto/vfio_ap_private.h |   25 +++++++++++++++++++++++++
> >   2 files changed, 50 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
> > index 3e8534b..34f982a 100644
> > --- a/drivers/s390/crypto/vfio_ap_private.h
> > +++ b/drivers/s390/crypto/vfio_ap_private.h
> > @@ -74,4 +74,29 @@ struct ap_matrix_mdev {
> >   extern int vfio_ap_mdev_register(void);
> >   extern void vfio_ap_mdev_unregister(void);
> >   
> > +static inline int vfio_ap_reset_queue(unsigned int apid, unsigned int apqi,
> > +				      unsigned int retry)
> > +{
> > +	struct ap_queue_status status;
> > +
> > +	do {
> > +		status = ap_zapq(AP_MKQID(apid, apqi));
> > +		switch (status.response_code) {
> > +		case AP_RESPONSE_NORMAL:
> > +			return 0;
> > +		case AP_RESPONSE_RESET_IN_PROGRESS:
> > +		case AP_RESPONSE_BUSY:
> > +			msleep(20);
> > +			break;
> > +		default:
> > +			pr_warn("%s: error zeroizing %02x.%04x: response code %d\n",
> > +				VFIO_AP_MODULE_NAME, apid, apqi,
> > +				status.response_code);
> How can we end up here? Does this mean that we just don't know what to
> do with this response, or is this something that should never happen?
> (How much sense does it make to print an error?)

There are additional response codes that could be returned; for example,
in the case of a catastrophic failure such as: The function can not be
performed because the AP was somehow deconfigured or the functiona
cannot be performed due to a machine check failure that caused the AP
path to be removed. It shouldn't happen, but all are possibilities.
I can get rid of the message and just return -EIO if you prefer.

> > +			return -EIO;
> > +		}
> > +	} while (retry--);
> > +
> > +	return -EBUSY;
> > +}
> > +
> >   #endif /* _VFIO_AP_PRIVATE_H_ */