[PATCH v7 11/22] s390: vfio-ap: sysfs interfaces to configure domains

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From: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>

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>
Reviewed-by: Halil Pasic <pasic@xxxxxxxxxxxxx>
Tested-by: Michael Mueller <mimu@xxxxxxxxxxxxx>
Tested-by: Farhan Ali <alifm@xxxxxxxxxxxxx>
Tested-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
---
 drivers/s390/crypto/vfio_ap_ops.c | 77 ++++++++++++++++++++++++++++++-
 1 file changed, 76 insertions(+), 1 deletion(-)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 07911fb9cdce..049256d785e2 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -204,10 +204,85 @@ static ssize_t unassign_adapter_store(struct device *dev,
 }
 DEVICE_ATTR_WO(unassign_adapter);
 
+static ssize_t assign_domain_store(struct device *dev,
+				   struct device_attribute *attr,
+				   const char *buf, size_t count)
+{
+	int ret;
+	unsigned long apqi;
+	struct mdev_device *mdev = mdev_from_dev(dev);
+	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
+	unsigned long max_apqi = matrix_mdev->matrix.aqm_max;
+
+	ret = kstrtoul(buf, 0, &apqi);
+	if (ret || (apqi > max_apqi)) {
+		pr_warn("%s: %s: domain id '%s' not a value from 0 to %02lu(%#04lx)\n",
+		       VFIO_AP_MODULE_NAME, __func__, buf, max_apqi, max_apqi);
+
+		if (!ret)
+			ret = -EINVAL;
+
+		return ret;
+	}
+
+	/* Set the bit in the AQM (bitmask) corresponding to the AP domain
+	 * number (APQI). The bits in the mask, from most significant to least
+	 * significant, correspond to numbers 0-255.
+	 */
+	mutex_lock(&matrix_dev.lock);
+	set_bit_inv(apqi, matrix_mdev->matrix.aqm);
+	ret = count;
+
+	mutex_unlock(&matrix_dev.lock);
+
+	return ret;
+}
+DEVICE_ATTR_WO(assign_domain);
+
+static ssize_t unassign_domain_store(struct device *dev,
+				     struct device_attribute *attr,
+				     const char *buf, size_t count)
+{
+	int ret;
+	unsigned long apqi;
+	struct mdev_device *mdev = mdev_from_dev(dev);
+	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
+	unsigned long max_apqi = matrix_mdev->matrix.aqm_max;
+
+	ret = kstrtoul(buf, 0, &apqi);
+	if (ret || (apqi > max_apqi)) {
+		pr_warn("%s: %s: domain id '%s' not a value from 0 to %02lu(%#04lx)\n",
+		       VFIO_AP_MODULE_NAME, __func__, buf, max_apqi, max_apqi);
+		ret = -EINVAL;
+		return ret;
+	}
+
+	mutex_lock(&matrix_dev.lock);
+	if (!test_bit_inv(apqi, matrix_mdev->matrix.aqm)) {
+		pr_warn("%s: %s: domain %02lu(%#04lx) not assigned\n",
+		       VFIO_AP_MODULE_NAME, __func__, apqi, apqi);
+
+		ret = -ENODEV;
+
+		goto done;
+	}
+
+	clear_bit_inv((unsigned long)apqi, matrix_mdev->matrix.aqm);
+	ret = count;
+
+done:
+	mutex_unlock(&matrix_dev.lock);
+
+	return ret;
+}
+DEVICE_ATTR_WO(unassign_domain);
+
 static struct attribute *vfio_ap_mdev_attrs[] = {
 	&dev_attr_assign_adapter.attr,
 	&dev_attr_unassign_adapter.attr,
-	NULL
+	&dev_attr_assign_domain.attr,
+	&dev_attr_unassign_domain.attr,
+	NULL,
 };
 
 static struct attribute_group vfio_ap_mdev_attr_group = {
-- 
2.17.0

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