The matrix of adapters and domains configured in a guest's CRYCB may
differ from the matrix of adapters and domains assigned to the matrix mdev,
so this patch introduces a sysfs attribute to display the matrix of a guest
using the matrix mdev. For a matrix mdev denoted by $uuid, the crycb for a
guest using the matrix mdev can be displayed as follows:

   cat /sys/devices/vfio_ap/matrix/$uuid/guest_matrix

If a guest is not using the matrix mdev at the time the crycb is displayed,
an error (ENODEV) will be returned.

Signed-off-by: Tony Krowiak <akrow...@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_ops.c | 58 +++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c 
b/drivers/s390/crypto/vfio_ap_ops.c
index b5ed36e2c948..779659074776 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -1086,6 +1086,63 @@ static ssize_t matrix_show(struct device *dev, struct 
device_attribute *attr,
 }
 static DEVICE_ATTR_RO(matrix);
 
+static ssize_t guest_matrix_show(struct device *dev,
+                                struct device_attribute *attr, char *buf)
+{
+       struct mdev_device *mdev = mdev_from_dev(dev);
+       struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
+       char *bufpos = buf;
+       unsigned long apid;
+       unsigned long apqi;
+       unsigned long apid1;
+       unsigned long apqi1;
+       unsigned long napm_bits = matrix_mdev->shadow_apcb.apm_max + 1;
+       unsigned long naqm_bits = matrix_mdev->shadow_apcb.aqm_max + 1;
+       int nchars = 0;
+       int n;
+
+       if (!vfio_ap_mdev_has_crycb(matrix_mdev))
+               return -ENODEV;
+
+       apid1 = find_first_bit_inv(matrix_mdev->shadow_apcb.apm, napm_bits);
+       apqi1 = find_first_bit_inv(matrix_mdev->shadow_apcb.aqm, naqm_bits);
+
+       mutex_lock(&matrix_dev->lock);
+
+       if ((apid1 < napm_bits) && (apqi1 < naqm_bits)) {
+               for_each_set_bit_inv(apid, matrix_mdev->shadow_apcb.apm,
+                                    napm_bits) {
+                       for_each_set_bit_inv(apqi,
+                                            matrix_mdev->shadow_apcb.aqm,
+                                            naqm_bits) {
+                               n = sprintf(bufpos, "%02lx.%04lx\n", apid,
+                                           apqi);
+                               bufpos += n;
+                               nchars += n;
+                       }
+               }
+       } else if (apid1 < napm_bits) {
+               for_each_set_bit_inv(apid, matrix_mdev->shadow_apcb.apm,
+                                    napm_bits) {
+                       n = sprintf(bufpos, "%02lx.\n", apid);
+                       bufpos += n;
+                       nchars += n;
+               }
+       } else if (apqi1 < naqm_bits) {
+               for_each_set_bit_inv(apqi, matrix_mdev->shadow_apcb.aqm,
+                                    naqm_bits) {
+                       n = sprintf(bufpos, ".%04lx\n", apqi);
+                       bufpos += n;
+                       nchars += n;
+               }
+       }
+
+       mutex_unlock(&matrix_dev->lock);
+
+       return nchars;
+}
+static DEVICE_ATTR_RO(guest_matrix);
+
 static struct attribute *vfio_ap_mdev_attrs[] = {
        &dev_attr_assign_adapter.attr,
        &dev_attr_unassign_adapter.attr,
@@ -1095,6 +1152,7 @@ static struct attribute *vfio_ap_mdev_attrs[] = {
        &dev_attr_unassign_control_domain.attr,
        &dev_attr_control_domains.attr,
        &dev_attr_matrix.attr,
+       &dev_attr_guest_matrix.attr,
        NULL,
 };
 
-- 
2.21.1

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