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

From: Tony Krowiak
Date: Wed Aug 15 2018 - 16:36:48 EST

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) {
+ return 0;
+ 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_ */