kvm.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Tony Krowiak <akrowiak@linux.ibm.com>
To: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org
Cc: jjherne@linux.ibm.com, freude@linux.ibm.com,
	borntraeger@de.ibm.com, cohuck@redhat.com,
	mjrosato@linux.ibm.com, pasic@linux.ibm.com,
	alex.williamson@redhat.com, kwankhede@nvidia.com,
	fiuczy@linux.ibm.com, Tony Krowiak <akrowiak@linux.ibm.com>
Subject: [PATCH v16 10/14] s390/zcrypt: driver callback to indicate resource in use
Date: Mon, 10 May 2021 12:44:19 -0400	[thread overview]
Message-ID: <20210510164423.346858-11-akrowiak@linux.ibm.com> (raw)
In-Reply-To: <20210510164423.346858-1-akrowiak@linux.ibm.com>

Introduces a new driver callback to prevent a root user from unbinding
an AP queue from its device driver if the queue is in use. The callback
will be invoked whenever a change to the AP bus's sysfs apmask or aqmask
attributes would result in one or more AP queues being removed from its
driver. If the callback responds in the affirmative for any driver
queried, the change to the apmask or aqmask will be rejected with a device
busy error.

For this patch, only non-default drivers will be queried. Currently,
there is only one non-default driver, the vfio_ap device driver. The
vfio_ap device driver facilitates pass-through of an AP queue to a
guest. The idea here is that a guest may be administered by a different
sysadmin than the host and we don't want AP resources to unexpectedly
disappear from a guest's AP configuration (i.e., adapters and domains
assigned to the matrix mdev). This will enforce the proper procedure for
removing AP resources intended for guest usage which is to
first unassign them from the matrix mdev, then unbind them from the
vfio_ap device driver.

Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
---
 drivers/s390/crypto/ap_bus.c | 160 ++++++++++++++++++++++++++++++++---
 drivers/s390/crypto/ap_bus.h |   4 +
 2 files changed, 154 insertions(+), 10 deletions(-)

diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c
index 2758d05a802d..b7653cec81ac 100644
--- a/drivers/s390/crypto/ap_bus.c
+++ b/drivers/s390/crypto/ap_bus.c
@@ -36,6 +36,7 @@
 #include <linux/mod_devicetable.h>
 #include <linux/debugfs.h>
 #include <linux/ctype.h>
+#include <linux/module.h>
 
 #include "ap_bus.h"
 #include "ap_debug.h"
@@ -1006,6 +1007,23 @@ static int modify_bitmap(const char *str, unsigned long *bitmap, int bits)
 	return 0;
 }
 
+static int ap_parse_bitmap_str(const char *str, unsigned long *bitmap, int bits,
+			       unsigned long *newmap)
+{
+	unsigned long size;
+	int rc;
+
+	size = BITS_TO_LONGS(bits) * sizeof(unsigned long);
+	if (*str == '+' || *str == '-') {
+		memcpy(newmap, bitmap, size);
+		rc = modify_bitmap(str, newmap, bits);
+	} else {
+		memset(newmap, 0, size);
+		rc = hex2bitmap(str, newmap, bits);
+	}
+	return rc;
+}
+
 int ap_parse_mask_str(const char *str,
 		      unsigned long *bitmap, int bits,
 		      struct mutex *lock)
@@ -1025,14 +1043,7 @@ int ap_parse_mask_str(const char *str,
 		kfree(newmap);
 		return -ERESTARTSYS;
 	}
-
-	if (*str == '+' || *str == '-') {
-		memcpy(newmap, bitmap, size);
-		rc = modify_bitmap(str, newmap, bits);
-	} else {
-		memset(newmap, 0, size);
-		rc = hex2bitmap(str, newmap, bits);
-	}
+	rc = ap_parse_bitmap_str(str, bitmap, bits, newmap);
 	if (rc == 0)
 		memcpy(bitmap, newmap, size);
 	mutex_unlock(lock);
@@ -1224,12 +1235,76 @@ static ssize_t apmask_show(struct bus_type *bus, char *buf)
 	return rc;
 }
 
+static int __verify_card_reservations(struct device_driver *drv, void *data)
+{
+	int rc = 0;
+	struct ap_driver *ap_drv = to_ap_drv(drv);
+	unsigned long *newapm = (unsigned long *)data;
+
+	/*
+	 * No need to verify whether the driver is using the queues if it is the
+	 * default driver.
+	 */
+	if (ap_drv->flags & AP_DRIVER_FLAG_DEFAULT)
+		return 0;
+
+	/*
+	 * increase the driver's module refcounter to be sure it is not
+	 * going away when we invoke the callback function.
+	 */
+	if (!try_module_get(drv->owner))
+		return 0;
+
+	if (ap_drv->in_use) {
+		rc = ap_drv->in_use(newapm, ap_perms.aqm);
+		if (rc)
+			rc = -EBUSY;
+	}
+
+	/* release the driver's module */
+	module_put(drv->owner);
+
+	return rc;
+}
+
+static int apmask_commit(unsigned long *newapm)
+{
+	int rc;
+	unsigned long reserved[BITS_TO_LONGS(AP_DEVICES)];
+
+	/*
+	 * Check if any bits in the apmask have been set which will
+	 * result in queues being removed from non-default drivers
+	 */
+	if (bitmap_andnot(reserved, newapm, ap_perms.apm, AP_DEVICES)) {
+		rc = bus_for_each_drv(&ap_bus_type, NULL, reserved,
+				      __verify_card_reservations);
+		if (rc)
+			return rc;
+	}
+
+	memcpy(ap_perms.apm, newapm, APMASKSIZE);
+
+	return 0;
+}
+
 static ssize_t apmask_store(struct bus_type *bus, const char *buf,
 			    size_t count)
 {
 	int rc;
+	DECLARE_BITMAP(newapm, AP_DEVICES);
+
+	if (mutex_lock_interruptible(&ap_perms_mutex))
+		return -ERESTARTSYS;
 
-	rc = ap_parse_mask_str(buf, ap_perms.apm, AP_DEVICES, &ap_perms_mutex);
+	rc = ap_parse_bitmap_str(buf, ap_perms.apm, AP_DEVICES, newapm);
+	if (rc)
+		goto done;
+
+	rc = apmask_commit(newapm);
+
+done:
+	mutex_unlock(&ap_perms_mutex);
 	if (rc)
 		return rc;
 
@@ -1255,12 +1330,77 @@ static ssize_t aqmask_show(struct bus_type *bus, char *buf)
 	return rc;
 }
 
+static int __verify_queue_reservations(struct device_driver *drv, void *data)
+{
+	int rc = 0;
+	struct ap_driver *ap_drv = to_ap_drv(drv);
+	unsigned long *newaqm = (unsigned long *)data;
+
+	/*
+	 * If the reserved bits do not identify queues reserved for use by the
+	 * non-default driver, there is no need to verify the driver is using
+	 * the queues.
+	 */
+	if (ap_drv->flags & AP_DRIVER_FLAG_DEFAULT)
+		return 0;
+
+	/*
+	 * increase the driver's module refcounter to be sure it is not
+	 * going away when we invoke the callback function.
+	 */
+	if (!try_module_get(drv->owner))
+		return 0;
+
+	if (ap_drv->in_use) {
+		rc = ap_drv->in_use(ap_perms.apm, newaqm);
+		if (rc)
+			return -EBUSY;
+	}
+
+	/* release the driver's module */
+	module_put(drv->owner);
+
+	return rc;
+}
+
+static int aqmask_commit(unsigned long *newaqm)
+{
+	int rc;
+	unsigned long reserved[BITS_TO_LONGS(AP_DOMAINS)];
+
+	/*
+	 * Check if any bits in the aqmask have been set which will
+	 * result in queues being removed from non-default drivers
+	 */
+	if (bitmap_andnot(reserved, newaqm, ap_perms.aqm, AP_DOMAINS)) {
+		rc = bus_for_each_drv(&ap_bus_type, NULL, reserved,
+				      __verify_queue_reservations);
+		if (rc)
+			return rc;
+	}
+
+	memcpy(ap_perms.aqm, newaqm, AQMASKSIZE);
+
+	return 0;
+}
+
 static ssize_t aqmask_store(struct bus_type *bus, const char *buf,
 			    size_t count)
 {
 	int rc;
+	DECLARE_BITMAP(newaqm, AP_DOMAINS);
+
+	if (mutex_lock_interruptible(&ap_perms_mutex))
+		return -ERESTARTSYS;
+
+	rc = ap_parse_bitmap_str(buf, ap_perms.aqm, AP_DOMAINS, newaqm);
+	if (rc)
+		goto done;
+
+	rc = aqmask_commit(newaqm);
 
-	rc = ap_parse_mask_str(buf, ap_perms.aqm, AP_DOMAINS, &ap_perms_mutex);
+done:
+	mutex_unlock(&ap_perms_mutex);
 	if (rc)
 		return rc;
 
diff --git a/drivers/s390/crypto/ap_bus.h b/drivers/s390/crypto/ap_bus.h
index 472efd3a755c..95c9da072f81 100644
--- a/drivers/s390/crypto/ap_bus.h
+++ b/drivers/s390/crypto/ap_bus.h
@@ -145,6 +145,7 @@ struct ap_driver {
 
 	int (*probe)(struct ap_device *);
 	void (*remove)(struct ap_device *);
+	int (*in_use)(unsigned long *apm, unsigned long *aqm);
 };
 
 #define to_ap_drv(x) container_of((x), struct ap_driver, driver)
@@ -293,6 +294,9 @@ void ap_queue_init_state(struct ap_queue *aq);
 struct ap_card *ap_card_create(int id, int queue_depth, int raw_device_type,
 			       int comp_device_type, unsigned int functions);
 
+#define APMASKSIZE (BITS_TO_LONGS(AP_DEVICES) * sizeof(unsigned long))
+#define AQMASKSIZE (BITS_TO_LONGS(AP_DOMAINS) * sizeof(unsigned long))
+
 struct ap_perms {
 	unsigned long ioctlm[BITS_TO_LONGS(AP_IOCTLS)];
 	unsigned long apm[BITS_TO_LONGS(AP_DEVICES)];
-- 
2.30.2


  parent reply	other threads:[~2021-05-10 16:45 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-10 16:44 [PATCH v16 00/14] s390/vfio-ap: dynamic configuration support Tony Krowiak
2021-05-10 16:44 ` [PATCH v16 01/14] s390/vfio-ap: fix memory leak in mdev remove callback Tony Krowiak
2021-05-10 16:44 ` [PATCH v16 02/14] s390/vfio-ap: use new AP bus interface to search for queue devices Tony Krowiak
2021-06-09 13:52   ` Jason J. Herne
2021-06-09 18:23     ` Tony Krowiak
2021-05-10 16:44 ` [PATCH v16 03/14] s390/vfio-ap: move probe and remove callbacks to vfio_ap_ops.c Tony Krowiak
2021-05-10 16:44 ` [PATCH v16 04/14] s390/vfio-ap: manage link between queue struct and matrix mdev Tony Krowiak
2021-05-10 16:44 ` [PATCH v16 05/14] s390/vfio-ap: introduce shadow APCB Tony Krowiak
2021-05-10 16:44 ` [PATCH v16 06/14] s390/vfio-ap: refresh guest's APCB by filtering APQNs assigned to mdev Tony Krowiak
2021-05-24 16:15   ` Halil Pasic
2021-06-01 11:25     ` Tony Krowiak
2021-05-10 16:44 ` [PATCH v16 07/14] s390/vfio-ap: allow assignment of unavailable AP queues to mdev device Tony Krowiak
2021-05-10 16:44 ` [PATCH v16 08/14] s390/vfio-ap: allow hot plug/unplug of AP resources using " Tony Krowiak
2021-05-10 16:44 ` [PATCH v16 09/14] s390/vfio-ap: reset queues after adapter/domain unassignment Tony Krowiak
2021-05-10 16:44 ` Tony Krowiak [this message]
2021-05-19 11:58   ` [PATCH v16 10/14] s390/zcrypt: driver callback to indicate resource in use Julian Wiedmann
2021-05-20 11:58     ` Harald Freudenberger
2021-05-20 15:28     ` Tony Krowiak
2021-05-10 16:44 ` [PATCH v16 11/14] s390/vfio-ap: implement in-use callback for vfio_ap driver Tony Krowiak
2021-05-10 16:44 ` [PATCH v16 12/14] s390/vfio-ap: sysfs attribute to display the guest's matrix Tony Krowiak
2021-05-10 16:44 ` [PATCH v16 13/14] s390/zcrypt: notify drivers on config changed and scan complete callbacks Tony Krowiak
2021-05-10 20:02   ` kernel test robot
2021-05-10 16:44 ` [PATCH v16 14/14] s390/vfio-ap: update docs to include dynamic config support Tony Krowiak
2021-05-18 13:26 ` [PATCH v16 00/14] s390/vfio-ap: dynamic configuration support Tony Krowiak
2021-05-18 16:54   ` Halil Pasic
2021-05-19 11:52     ` Tony Krowiak
2021-06-09 11:36 ` Tony Krowiak

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210510164423.346858-11-akrowiak@linux.ibm.com \
    --to=akrowiak@linux.ibm.com \
    --cc=alex.williamson@redhat.com \
    --cc=borntraeger@de.ibm.com \
    --cc=cohuck@redhat.com \
    --cc=fiuczy@linux.ibm.com \
    --cc=freude@linux.ibm.com \
    --cc=jjherne@linux.ibm.com \
    --cc=kvm@vger.kernel.org \
    --cc=kwankhede@nvidia.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-s390@vger.kernel.org \
    --cc=mjrosato@linux.ibm.com \
    --cc=pasic@linux.ibm.com \
    --subject='Re: [PATCH v16 10/14] s390/zcrypt: driver callback to indicate resource in use' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).