Re: [PATCH v6 11/21] s390: vfio-ap: sysfs interfaces to configure domains

From: Pierre Morel
Date: Mon Jul 09 2018 - 08:14:04 EST


On 29/06/2018 23:11, Tony Krowiak wrote:
Provides the sysfs interfaces for assigning AP domains to
and unassigning AP domains from a mediated matrix device.

An AP domain ID corresponds to an AP queue index (APQI). For
each domain assigned to the mediated matrix device, its
corresponging APQI is stored in an AP queue mask (AQM).
The bits in the AQM, from most significant to least
significant bit, correspond to AP domain numbers 0 to 255.
When a domain is assigned, the bit corresponding to its
APQI will be set in the AQM. Likewise, when a domain is
unassigned, the bit corresponding to its APQI will be
cleared from the AQM.

The relevant sysfs structures are:

/sys/devices/vfio_ap
... [matrix]
...... [mdev_supported_types]
......... [vfio_ap-passthrough]
............ [devices]
...............[$uuid]
.................. assign_domain
.................. unassign_domain

To assign a domain to the $uuid mediated matrix device,
write the domain's ID to the assign_domain file. To
unassign a domain, write the domain's ID to the
unassign_domain file. The ID is specified using
conventional semantics: If it begins with 0x, the number
will be parsed as a hexadecimal (case insensitive) number;
if it begins with 0, it will be parsed as an octal number;
otherwise, it will be parsed as a decimal number.

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

echo 173 > assign_domain

or

echo 0255 > assign_domain

or

echo 0xad > assign_domain

To unassign domain 173 (0xad):

echo 173 > unassign_domain

or

echo 0255 > unassign_domain

or

echo 0xad > unassign_domain

The assignment will be rejected:

* If the domain ID exceeds the maximum value for an AP domain:

* If the AP Extended Addressing (APXA) facility is installed,
the max value is 255

* Else the max value is 15

* If no AP adapters have yet been assigned and there are
no AP queues reserved by the VFIO AP driver that have an APQN
with an APQI matching that of the AP domain number being
assigned.

* If any of the APQNs that can be derived from the intersection
of the APQI being assigned and the AP adapter ID (APID) of
each of the AP adapters previously assigned can not be matched
with an APQN of an AP queue device reserved by the VFIO AP
driver.

Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
---
drivers/s390/crypto/vfio_ap_ops.c | 173 ++++++++++++++++++++++++++++++++++++-
1 files changed, 172 insertions(+), 1 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index a4351bd..a5b06e7 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -170,6 +170,27 @@ static int vfio_ap_queue_has_apid(struct device *dev, void *data)
}

/**
+ * vfio_ap_queue_has_apqi
+ *
+ * @dev: an AP queue device
+ * @data: an AP queue index
+ *
+ * Flags whether any AP queue device has a particular AP queue index
+ *
+ * Returns 0 to indicate the function succeeded
+ */
+static int vfio_ap_queue_has_apqi(struct device *dev, void *data)
+{
+ struct vfio_id_reserved *id_res = data;
+ struct ap_queue *ap_queue = to_ap_queue(dev);
+
+ if (id_res->id == AP_QID_QUEUE(ap_queue->qid))
+ id_res->reserved = true;
+
+ return 0;
+}
+
+/**
* vfio_ap_verify_qid_reserved
*
* @matrix_dev: a mediated matrix device
@@ -236,6 +257,42 @@ static int vfio_ap_verify_apid_reserved(struct ap_matrix_dev *matrix_dev,
return -EPERM;
}

+/**
+ * vfio_ap_verify_apqi_reserved
+ *
+ * @matrix_dev: a mediated matrix device
+ * @apqi: an AP queue index
+ *
+ * Verifies that an AP queue with @apqi is reserved by the VFIO AP device
+ * driver.
+ *
+ * Returns 0 if an AP queue with @apqi is reserved; otherwise, returns -ENODEV.
+ */
+static int vfio_ap_verify_apqi_reserved(struct ap_matrix_dev *matrix_dev,
+ const char *mdev_name,
+ unsigned long apqi)
+{
+ int ret;
+ struct vfio_id_reserved id_res;
+
+ id_res.id = apqi;
+ id_res.reserved = false;
+
+ ret = driver_for_each_device(matrix_dev->device.driver, NULL, &id_res,
+ vfio_ap_queue_has_apqi);
+ if (ret)
+ return ret;
+
+ if (id_res.reserved)
+ return 0;
+
+ pr_err("%s: mdev %s using queue %04lx not reserved by %s driver",
+ VFIO_AP_MODULE_NAME, mdev_name, apqi,
+ VFIO_AP_DRV_NAME);
+
+ return -EPERM;
+}
+
static int vfio_ap_verify_queues_reserved(struct ap_matrix_dev *matrix_dev,
const char *mdev_name,
struct ap_matrix *matrix)
@@ -417,10 +474,124 @@ static ssize_t unassign_adapter_store(struct device *dev,
}
DEVICE_ATTR_WO(unassign_adapter);

+/**
+ * vfio_ap_validate_apqi
+ *
+ * @matrix_mdev: the mediated matrix device
+ * @apqi: the APQI (domain ID) to validate
+ *
+ * Validates the value of @apqi:
+ * * If there are no AP adapters assigned, then there must be at least
+ * one AP queue device reserved by the VFIO AP device driver with an
+ * APQN containing @apqi.

Same as in preceding patch, I do not understand why you need this.

Pierre


--
Pierre Morel
Linux/KVM/QEMU in BÃblingen - Germany