linux-imx

s390: vfio-ap: sysfs interfaces to configure adapters

Introduces two new sysfs attributes for the VFIO mediated
matrix device for assigning AP adapters to and unassigning
AP adapters from a mediated matrix device. The IDs of the
AP adapters assigned to the mediated matrix device will be
stored in an AP mask (APM).

The bits in the APM, from most significant to least significant
bit, correspond to AP adapter IDs (APID) 0 to 255. On
some systems, the maximum allowable adapter number may be less
than 255 - depending upon the host's AP configuration - and
assignment may be rejected if the input adapter ID exceeds the
limit.

When an adapter is assigned, the bit corresponding to the APID
will be set in the APM. Likewise, when an adapter is
unassigned, the bit corresponding to the APID will be cleared
from the APM.

In order to successfully assign an adapter, the APQNs derived from
the adapter ID being assigned and the queue indexes of all domains
previously assigned:

1. Must be bound to the vfio_ap device driver.

2. Must not be assigned to any other mediated matrix device

If there are no domains assigned to the mdev, then there must
be an AP queue bound to the vfio_ap device driver with an
APQN containing the APID, otherwise all domains
subsequently assigned will fail because there will be no
AP queues bound with an APQN containing the adapter ID.

Assigning or un-assigning an AP adapter will be rejected if
a guest using the mediated matrix device is running.

The relevant sysfs structures are:

/sys/devices/vfio_ap/matrix/
...... [mdev_supported_types]
......... [vfio_ap-passthrough]
............ [devices]
...............[$uuid]
.................. assign_adapter
.................. unassign_adapter

To assign an adapter to the $uuid mediated matrix device's APM,
write the APID to the assign_adapter file. To unassign an adapter,
write the APID to the unassign_adapter file. The APID is specified
using conventional semantics: If it begins with 0x the number will
be parsed as a hexadecimal number; if it begins with a 0 the number
will be parsed as an octal number; otherwise, it will be parsed as a
decimal number.

For example, to assign adapter 173 (0xad) to the mediated matrix
device $uuid:

	echo 173 > assign_adapter

	or

	echo 0xad > assign_adapter

	or

	echo 0255 > assign_adapter

To unassign adapter 173 (0xad):

	echo 173 > unassign_adapter

	or

	echo 0xad > unassign_adapter

	or

	echo 0255 > unassign_adapter

Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Tested-by: Michael Mueller <mimu@linux.ibm.com>
Tested-by: Farhan Ali <alifm@linux.ibm.com>
Tested-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <20180925231641.4954-7-akrowiak@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>