s390/vfio-ap: Add write support to sysfs attr ap_config

Allow writing a complete set of masks to ap_config. Doing so will
cause the vfio-ap driver to replace the vfio-ap mediated device's
matrix masks with the given set of masks. If the given state cannot
be set, then no changes are made to the vfio-ap mediated device.

The format of the data written to ap_config is as follows:
{amask},{dmask},{cmask}\n

\n is a newline character.

amask, dmask, and cmask are masks identifying which adapters, domains,
and control domains should be assigned to the mediated device.

The format of a mask is as follows:
0xNN..NN

Where NN..NN is 64 hexadecimal characters representing a 256-bit value.
The leftmost (highest order) bit represents adapter/domain 0.

For an example set of masks that represent your mdev's current
configuration, simply cat ap_config.

This attribute is intended to be used by an mdevctl callout script
supporting the mdev type vfio_ap-passthrough to atomically update a
vfio-ap mediated device's state.

Signed-off-by: "Jason J. Herne" <jjherne@linux.ibm.com>
Reviewed-by: Tony Krowiak <akrowiak@linux.ibm.com>
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Link: https://lore.kernel.org/r/20240415152555.13152-5-jjherne@linux.ibm.com
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

drivers/s390/crypto/vfio_ap_ops.c

@@ -1119,20 +1119,29 @@ static void vfio_ap_mdev_unlink_adapter(struct ap_matrix_mdev *matrix_mdev,
 	}
 }
 
-static void vfio_ap_mdev_hot_unplug_adapter(struct ap_matrix_mdev *matrix_mdev,
-					    unsigned long apid)
+static void vfio_ap_mdev_hot_unplug_adapters(struct ap_matrix_mdev *matrix_mdev,
+					     unsigned long *apids)
 {
 	struct vfio_ap_queue *q, *tmpq;
 	struct list_head qlist;
+	unsigned long apid;
+	bool apcb_update = false;
 
 	INIT_LIST_HEAD(&qlist);
-	vfio_ap_mdev_unlink_adapter(matrix_mdev, apid, &qlist);
 
-	if (test_bit_inv(apid, matrix_mdev->shadow_apcb.apm)) {
-		clear_bit_inv(apid, matrix_mdev->shadow_apcb.apm);
-		vfio_ap_mdev_update_guest_apcb(matrix_mdev);
+	for_each_set_bit_inv(apid, apids, AP_DEVICES) {
+		vfio_ap_mdev_unlink_adapter(matrix_mdev, apid, &qlist);
+
+		if (test_bit_inv(apid, matrix_mdev->shadow_apcb.apm)) {
+			clear_bit_inv(apid, matrix_mdev->shadow_apcb.apm);
+			apcb_update = true;
+		}
 	}
 
+	/* Only update apcb if needed to avoid impacting guest */
+	if (apcb_update)
+		vfio_ap_mdev_update_guest_apcb(matrix_mdev);
+
 	vfio_ap_mdev_reset_qlist(&qlist);
 
 	list_for_each_entry_safe(q, tmpq, &qlist, reset_qnode) {
@@ -1141,6 +1150,16 @@ static void vfio_ap_mdev_hot_unplug_adapter(struct ap_matrix_mdev *matrix_mdev,
 	}
 }
 
+static void vfio_ap_mdev_hot_unplug_adapter(struct ap_matrix_mdev *matrix_mdev,
+					    unsigned long apid)
+{
+	DECLARE_BITMAP(apids, AP_DEVICES);
+
+	bitmap_zero(apids, AP_DEVICES);
+	set_bit_inv(apid, apids);
+	vfio_ap_mdev_hot_unplug_adapters(matrix_mdev, apids);
+}
+
 /**
  * unassign_adapter_store - parses the APID from @buf and clears the
  * corresponding bit in the mediated matrix device's APM
@@ -1301,20 +1320,29 @@ static void vfio_ap_mdev_unlink_domain(struct ap_matrix_mdev *matrix_mdev,
 	}
 }
 
-static void vfio_ap_mdev_hot_unplug_domain(struct ap_matrix_mdev *matrix_mdev,
-					   unsigned long apqi)
+static void vfio_ap_mdev_hot_unplug_domains(struct ap_matrix_mdev *matrix_mdev,
+					    unsigned long *apqis)
 {
 	struct vfio_ap_queue *q, *tmpq;
 	struct list_head qlist;
+	unsigned long apqi;
+	bool apcb_update = false;
 
 	INIT_LIST_HEAD(&qlist);
-	vfio_ap_mdev_unlink_domain(matrix_mdev, apqi, &qlist);
 
-	if (test_bit_inv(apqi, matrix_mdev->shadow_apcb.aqm)) {
-		clear_bit_inv(apqi, matrix_mdev->shadow_apcb.aqm);
-		vfio_ap_mdev_update_guest_apcb(matrix_mdev);
+	for_each_set_bit_inv(apqi, apqis, AP_DOMAINS) {
+		vfio_ap_mdev_unlink_domain(matrix_mdev, apqi, &qlist);
+
+		if (test_bit_inv(apqi, matrix_mdev->shadow_apcb.aqm)) {
+			clear_bit_inv(apqi, matrix_mdev->shadow_apcb.aqm);
+			apcb_update = true;
+		}
 	}
 
+	/* Only update apcb if needed to avoid impacting guest */
+	if (apcb_update)
+		vfio_ap_mdev_update_guest_apcb(matrix_mdev);
+
 	vfio_ap_mdev_reset_qlist(&qlist);
 
 	list_for_each_entry_safe(q, tmpq, &qlist, reset_qnode) {
@@ -1323,6 +1351,16 @@ static void vfio_ap_mdev_hot_unplug_domain(struct ap_matrix_mdev *matrix_mdev,
 	}
 }
 
+static void vfio_ap_mdev_hot_unplug_domain(struct ap_matrix_mdev *matrix_mdev,
+					   unsigned long apqi)
+{
+	DECLARE_BITMAP(apqis, AP_DOMAINS);
+
+	bitmap_zero(apqis, AP_DEVICES);
+	set_bit_inv(apqi, apqis);
+	vfio_ap_mdev_hot_unplug_domains(matrix_mdev, apqis);
+}
+
 /**
  * unassign_domain_store - parses the APQI from @buf and clears the
  * corresponding bit in the mediated matrix device's AQM
@@ -1590,10 +1628,136 @@ static ssize_t ap_config_show(struct device *dev, struct device_attribute *attr,
 	return idx;
 }
 
+/* Number of characters needed for a complete hex mask representing the bits in ..  */
+#define AP_DEVICES_STRLEN	(AP_DEVICES / 4 + 3)
+#define AP_DOMAINS_STRLEN	(AP_DOMAINS / 4 + 3)
+#define AP_CONFIG_STRLEN	(AP_DEVICES_STRLEN + 2 * AP_DOMAINS_STRLEN)
+
+static int parse_bitmap(char **strbufptr, unsigned long *bitmap, int nbits)
+{
+	char *curmask;
+
+	curmask = strsep(strbufptr, ",\n");
+	if (!curmask)
+		return -EINVAL;
+
+	bitmap_clear(bitmap, 0, nbits);
+	return ap_hex2bitmap(curmask, bitmap, nbits);
+}
+
+static int ap_matrix_overflow_check(struct ap_matrix_mdev *matrix_mdev)
+{
+	unsigned long bit;
+
+	for_each_set_bit_inv(bit, matrix_mdev->matrix.apm, AP_DEVICES) {
+		if (bit > matrix_mdev->matrix.apm_max)
+			return -ENODEV;
+	}
+
+	for_each_set_bit_inv(bit, matrix_mdev->matrix.aqm, AP_DOMAINS) {
+		if (bit > matrix_mdev->matrix.aqm_max)
+			return -ENODEV;
+	}
+
+	for_each_set_bit_inv(bit, matrix_mdev->matrix.adm, AP_DOMAINS) {
+		if (bit > matrix_mdev->matrix.adm_max)
+			return -ENODEV;
+	}
+
+	return 0;
+}
+
+static void ap_matrix_copy(struct ap_matrix *dst, struct ap_matrix *src)
+{
+	/* This check works around false positive gcc -Wstringop-overread */
+	if (!src)
+		return;
+
+	bitmap_copy(dst->apm, src->apm, AP_DEVICES);
+	bitmap_copy(dst->aqm, src->aqm, AP_DOMAINS);
+	bitmap_copy(dst->adm, src->adm, AP_DOMAINS);
+}
+
 static ssize_t ap_config_store(struct device *dev, struct device_attribute *attr,
 			       const char *buf, size_t count)
 {
-	return count;
+	struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);
+	struct ap_matrix m_new, m_old, m_added, m_removed;
+	DECLARE_BITMAP(apm_filtered, AP_DEVICES);
+	unsigned long newbit;
+	char *newbuf, *rest;
+	int rc = count;
+	bool do_update;
+
+	newbuf = kstrndup(buf, AP_CONFIG_STRLEN, GFP_KERNEL);
+	if (!newbuf)
+		return -ENOMEM;
+	rest = newbuf;
+
+	mutex_lock(&ap_perms_mutex);
+	get_update_locks_for_mdev(matrix_mdev);
+
+	/* Save old state */
+	ap_matrix_copy(&m_old, &matrix_mdev->matrix);
+	if (parse_bitmap(&rest, m_new.apm, AP_DEVICES) ||
+	    parse_bitmap(&rest, m_new.aqm, AP_DOMAINS) ||
+	    parse_bitmap(&rest, m_new.adm, AP_DOMAINS)) {
+		rc = -EINVAL;
+		goto out;
+	}
+
+	bitmap_andnot(m_removed.apm, m_old.apm, m_new.apm, AP_DEVICES);
+	bitmap_andnot(m_removed.aqm, m_old.aqm, m_new.aqm, AP_DOMAINS);
+	bitmap_andnot(m_added.apm, m_new.apm, m_old.apm, AP_DEVICES);
+	bitmap_andnot(m_added.aqm, m_new.aqm, m_old.aqm, AP_DOMAINS);
+
+	/* Need new bitmaps in matrix_mdev for validation */
+	ap_matrix_copy(&matrix_mdev->matrix, &m_new);
+
+	/* Ensure new state is valid, else undo new state */
+	rc = vfio_ap_mdev_validate_masks(matrix_mdev);
+	if (rc) {
+		ap_matrix_copy(&matrix_mdev->matrix, &m_old);
+		goto out;
+	}
+	rc = ap_matrix_overflow_check(matrix_mdev);
+	if (rc) {
+		ap_matrix_copy(&matrix_mdev->matrix, &m_old);
+		goto out;
+	}
+	rc = count;
+
+	/* Need old bitmaps in matrix_mdev for unplug/unlink */
+	ap_matrix_copy(&matrix_mdev->matrix, &m_old);
+
+	/* Unlink removed adapters/domains */
+	vfio_ap_mdev_hot_unplug_adapters(matrix_mdev, m_removed.apm);
+	vfio_ap_mdev_hot_unplug_domains(matrix_mdev, m_removed.aqm);
+
+	/* Need new bitmaps in matrix_mdev for linking new adapters/domains */
+	ap_matrix_copy(&matrix_mdev->matrix, &m_new);
+
+	/* Link newly added adapters */
+	for_each_set_bit_inv(newbit, m_added.apm, AP_DEVICES)
+		vfio_ap_mdev_link_adapter(matrix_mdev, newbit);
+
+	for_each_set_bit_inv(newbit, m_added.aqm, AP_DOMAINS)
+		vfio_ap_mdev_link_domain(matrix_mdev, newbit);
+
+	/* filter resources not bound to vfio-ap */
+	do_update = vfio_ap_mdev_filter_matrix(matrix_mdev, apm_filtered);
+	do_update |= vfio_ap_mdev_filter_cdoms(matrix_mdev);
+
+	/* Apply changes to shadow apbc if things changed */
+	if (do_update) {
+		vfio_ap_mdev_update_guest_apcb(matrix_mdev);
+		reset_queues_for_apids(matrix_mdev, apm_filtered);
+	}
+out:
+	release_update_locks_for_mdev(matrix_mdev);
+	mutex_unlock(&ap_perms_mutex);
+	kfree(newbuf);
+	return rc;
 }
 static DEVICE_ATTR_RW(ap_config);
 

drivers/s390/crypto/vfio_ap_private.h

@@ -75,11 +75,11 @@ extern struct ap_matrix_dev *matrix_dev;
  */
 struct ap_matrix {
 	unsigned long apm_max;
-	DECLARE_BITMAP(apm, 256);
+	DECLARE_BITMAP(apm, AP_DEVICES);
 	unsigned long aqm_max;
-	DECLARE_BITMAP(aqm, 256);
+	DECLARE_BITMAP(aqm, AP_DOMAINS);
 	unsigned long adm_max;
-	DECLARE_BITMAP(adm, 256);
+	DECLARE_BITMAP(adm, AP_DOMAINS);
 };
 
 /**