From: Halil Pasic <pasic@linux.ibm.com>
To: Tony Krowiak <akrowiak@linux.ibm.com>
Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org, freude@linux.ibm.com,
borntraeger@de.ibm.com, cohuck@redhat.com,
mjrosato@linux.ibm.com, alex.williamson@redhat.com,
kwankhede@nvidia.com, fiuczy@linux.ibm.com,
frankja@linux.ibm.com, david@redhat.com, imbrenda@linux.ibm.com,
hca@linux.ibm.com, gor@linux.ibm.com
Subject: Re: [PATCH v10 04/16] s390/zcrypt: driver callback to indicate resource in use
Date: Fri, 25 Sep 2020 11:24:10 +0200 [thread overview]
Message-ID: <20200925112410.4134faae.pasic@linux.ibm.com> (raw)
In-Reply-To: <20200821195616.13554-5-akrowiak@linux.ibm.com>
On Fri, 21 Aug 2020 15:56:04 -0400
Tony Krowiak <akrowiak@linux.ibm.com> wrote:
> 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 intent of
> this callback is to provide a driver with the means to prevent a root user
> from inadvertently taking a queue away from a matrix mdev and giving it to
> the host while it is assigned to the matrix mdev. 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
> in use 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, domains and
> control 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>
> Reported-by: kernel test robot <lkp@intel.com>
> ---
> drivers/s390/crypto/ap_bus.c | 148 ++++++++++++++++++++++++++++++++---
> drivers/s390/crypto/ap_bus.h | 4 +
> 2 files changed, 142 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c
> index 24a1940b829e..db27bd931308 100644
> --- a/drivers/s390/crypto/ap_bus.c
> +++ b/drivers/s390/crypto/ap_bus.c
> @@ -35,6 +35,7 @@
> #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"
> @@ -889,6 +890,23 @@ 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)
> @@ -908,14 +926,7 @@ 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);
> @@ -1107,12 +1118,70 @@ 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;
> +
> + /* The non-default driver's module must be loaded */
> + if (!try_module_get(drv->owner))
> + return 0;
> +
> + if (ap_drv->in_use)
> + if (ap_drv->in_use(newapm, ap_perms.aqm))
> + rc = -EADDRINUSE;
> +
> + 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;
> + }
I understand the above asks all the non-default drivers if some of the
queues are 'used'. But AFAIU this reflects the truth ap_drv->in_use()
is only telling us something about a given moment...
> +
> + memcpy(ap_perms.apm, newapm, APMASKSIZE);
... So I fail to understand what will prevent us from performing a
successful commit if some of the resources become 'used' between
the call to the in_use() callback and the memcpy.
Of course I might be wrong.
BTW I was never a fan of this mechanism, so I don't mind if it
does not work perfectly, and this should catch most of the cases. Just
want to make sure we don't introduce more confusion than necessary.
> +
> + 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_bitmap_str(buf, ap_perms.apm, AP_DEVICES, newapm);
> + if (rc)
> + goto done;
>
> - rc = ap_parse_mask_str(buf, ap_perms.apm, AP_DEVICES, &ap_perms_mutex);
> + rc = apmask_commit(newapm);
> +
> +done:
> + mutex_unlock(&ap_perms_mutex);
> if (rc)
> return rc;
>
> @@ -1138,12 +1207,71 @@ 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;
> +
> + /* The non-default driver's module must be loaded */
> + if (!try_module_get(drv->owner))
> + return 0;
> +
> + if (ap_drv->in_use)
> + if (ap_drv->in_use(ap_perms.apm, newaqm))
> + rc = -EADDRINUSE;
> +
> + 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);
> +
Same here.
Regards,
Halil
> + return 0;
> +}
> +
> static ssize_t aqmask_store(struct bus_type *bus, const char *buf,
> size_t count)
> {
> int rc;
> + DECLARE_BITMAP(newaqm, AP_DOMAINS);
>
> - rc = ap_parse_mask_str(buf, ap_perms.aqm, AP_DOMAINS, &ap_perms_mutex);
> + 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);
> +
> +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 1ea046324e8f..48c57b3d53a0 100644
> --- a/drivers/s390/crypto/ap_bus.h
> +++ b/drivers/s390/crypto/ap_bus.h
> @@ -136,6 +136,7 @@ struct ap_driver {
>
> int (*probe)(struct ap_device *);
> void (*remove)(struct ap_device *);
> + bool (*in_use)(unsigned long *apm, unsigned long *aqm);
> };
>
> #define to_ap_drv(x) container_of((x), struct ap_driver, driver)
> @@ -255,6 +256,9 @@ 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)];
next prev parent reply other threads:[~2020-09-25 9:24 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-21 19:56 [PATCH v10 00/16] s390/vfio-ap: dynamic configuration support Tony Krowiak
2020-08-21 19:56 ` [PATCH v10 01/16] s390/vfio-ap: add version vfio_ap module Tony Krowiak
2020-08-25 10:04 ` Cornelia Huck
2020-08-26 14:49 ` Tony Krowiak
2020-08-27 10:32 ` Cornelia Huck
2020-08-27 14:39 ` Tony Krowiak
2020-08-28 8:10 ` Cornelia Huck
2020-08-21 19:56 ` [PATCH v10 02/16] s390/vfio-ap: use new AP bus interface to search for queue devices Tony Krowiak
2020-08-25 10:13 ` Cornelia Huck
2020-08-27 14:24 ` Tony Krowiak
2020-08-28 8:13 ` Cornelia Huck
2020-08-28 15:10 ` Tony Krowiak
2020-09-25 2:11 ` Halil Pasic
2020-10-16 20:59 ` Tony Krowiak
2020-09-04 8:11 ` Christian Borntraeger
2020-09-08 18:54 ` Tony Krowiak
2020-09-25 2:27 ` Halil Pasic
2020-09-29 13:07 ` Tony Krowiak
2020-09-29 13:37 ` Halil Pasic
2020-09-29 20:57 ` Tony Krowiak
2020-08-21 19:56 ` [PATCH v10 03/16] s390/vfio-ap: manage link between queue struct and matrix mdev Tony Krowiak
2020-08-25 10:25 ` Cornelia Huck
2020-08-28 23:05 ` Tony Krowiak
2020-09-04 8:15 ` Christian Borntraeger
2020-09-08 19:03 ` Tony Krowiak
2020-09-25 7:58 ` Halil Pasic
2020-08-21 19:56 ` [PATCH v10 04/16] s390/zcrypt: driver callback to indicate resource in use Tony Krowiak
2020-09-14 15:29 ` Cornelia Huck
2020-09-15 19:32 ` Tony Krowiak
2020-09-17 12:14 ` Cornelia Huck
2020-09-17 13:54 ` Tony Krowiak
2020-09-25 9:24 ` Halil Pasic [this message]
2020-09-29 13:59 ` Tony Krowiak
2020-08-21 19:56 ` [PATCH v10 05/16] s390/vfio-ap: implement in-use callback for vfio_ap driver Tony Krowiak
2020-09-14 15:31 ` Cornelia Huck
2020-09-25 9:29 ` Halil Pasic
2020-09-29 14:00 ` Tony Krowiak
2020-08-21 19:56 ` [PATCH v10 06/16] s390/vfio-ap: introduce shadow APCB Tony Krowiak
2020-09-17 14:22 ` Cornelia Huck
2020-09-18 17:03 ` Tony Krowiak
2020-09-26 1:38 ` Halil Pasic
2020-09-29 16:04 ` Tony Krowiak
2020-09-29 16:19 ` Halil Pasic
2020-08-21 19:56 ` [PATCH v10 07/16] s390/vfio-ap: sysfs attribute to display the guest's matrix Tony Krowiak
2020-09-17 14:34 ` Cornelia Huck
2020-09-18 17:09 ` Tony Krowiak
2020-09-26 7:16 ` Halil Pasic
2020-09-29 21:00 ` Tony Krowiak
2020-08-21 19:56 ` [PATCH v10 08/16] s390/vfio-ap: filter matrix for unavailable queue devices Tony Krowiak
2020-09-26 8:24 ` Halil Pasic
2020-09-29 21:59 ` Tony Krowiak
2020-08-21 19:56 ` [PATCH v10 09/16] s390/vfio-ap: allow assignment of unavailable AP queues to mdev device Tony Krowiak
2020-09-26 23:49 ` Halil Pasic
2020-09-30 12:59 ` Tony Krowiak
2020-09-30 22:29 ` Halil Pasic
2020-08-21 19:56 ` [PATCH v10 10/16] s390/vfio-ap: allow configuration of matrix mdev in use by a KVM guest Tony Krowiak
2020-09-27 0:03 ` Halil Pasic
2020-09-30 13:19 ` Tony Krowiak
2020-08-21 19:56 ` [PATCH v10 11/16] s390/vfio-ap: allow hot plug/unplug of AP resources using mdev device Tony Krowiak
2020-09-28 1:01 ` Halil Pasic
2020-10-05 16:24 ` Tony Krowiak
2020-10-05 18:30 ` Halil Pasic
2020-10-05 21:48 ` Tony Krowiak
2020-10-05 23:05 ` Tony Krowiak
2020-08-21 19:56 ` [PATCH v10 12/16] s390/zcrypt: Notify driver on config changed and scan complete callbacks Tony Krowiak
2020-09-27 1:39 ` Halil Pasic
2020-08-21 19:56 ` [PATCH v10 13/16] s390/vfio-ap: handle host AP config change notification Tony Krowiak
2020-09-28 1:38 ` Halil Pasic
2020-10-12 20:53 ` Tony Krowiak
2020-10-12 21:27 ` Tony Krowiak
2020-08-21 19:56 ` [PATCH v10 14/16] s390/vfio-ap: handle AP bus scan completed notification Tony Krowiak
2020-09-28 2:11 ` Halil Pasic
2020-08-21 19:56 ` [PATCH v10 15/16] s390/vfio-ap: handle probe/remove not due to host AP config changes Tony Krowiak
2020-09-28 2:45 ` Halil Pasic
2020-08-21 19:56 ` [PATCH v10 16/16] s390/vfio-ap: update docs to include dynamic config support Tony Krowiak
2020-08-25 10:45 ` Cornelia Huck
2020-08-31 18:34 ` Tony Krowiak
2020-09-28 2:48 ` Halil Pasic
2020-10-16 16:36 ` Tony Krowiak
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