From: Tony Krowiak <akrowiak@linux.ibm.com>
To: pmorel@linux.ibm.com, linux-s390@vger.kernel.org,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: freude@linux.ibm.com, borntraeger@de.ibm.com, cohuck@redhat.com,
frankja@linux.ibm.com, david@redhat.com, schwidefsky@de.ibm.com,
heiko.carstens@de.ibm.com, pasic@linux.ibm.com,
alex.williamson@redhat.com, kwankhede@nvidia.com
Subject: Re: [PATCH 1/7] s390: zcrypt: driver callback to indicate resource in use
Date: Tue, 16 Apr 2019 09:11:19 -0400 [thread overview]
Message-ID: <8ee6f624-b698-bf83-2ae0-e292ad2512fc@linux.ibm.com> (raw)
In-Reply-To: <c575e772-59e2-9fed-5ade-24701d4f2b49@linux.ibm.com>
On 4/16/19 3:52 AM, Pierre Morel wrote:
> On 11/04/2019 23:03, Tony Krowiak 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. This prevents
>> a root user from inadvertently taking a queue away from a guest and
>> giving it to the host, or vice versa. The callback will be invoked
>> whenever a change to the AP bus's apmask or aqmask sysfs interfaces may
>> 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 manages AP queues passed through to one or more
>> guests and we don't want to unexpectedly take AP resources away from
>> guests which are most likely independently administered.
>>
>> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
>> ---
>> drivers/s390/crypto/ap_bus.c | 138
>> +++++++++++++++++++++++++++++++++++++++++--
>> drivers/s390/crypto/ap_bus.h | 3 +
>> 2 files changed, 135 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c
>> index 1546389d71db..66a5a9d9fae6 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"
>> @@ -980,9 +981,11 @@ int ap_parse_mask_str(const char *str,
>> newmap = kmalloc(size, GFP_KERNEL);
>> if (!newmap)
>> return -ENOMEM;
>> - if (mutex_lock_interruptible(lock)) {
>> - kfree(newmap);
>> - return -ERESTARTSYS;
>> + if (lock) {
>> + if (mutex_lock_interruptible(lock)) {
>> + kfree(newmap);
>> + return -ERESTARTSYS;
>> + }
>> }
>> if (*str == '+' || *str == '-') {
>> @@ -994,7 +997,10 @@ int ap_parse_mask_str(const char *str,
>> }
>> if (rc == 0)
>> memcpy(bitmap, newmap, size);
>> - mutex_unlock(lock);
>> +
>> + if (lock)
>> + mutex_unlock(lock);
>> +
>> kfree(newmap);
>> return rc;
>> }
>> @@ -1181,12 +1187,72 @@ 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;
>> +
>> + /*
>> + * If the reserved bits do not identify cards 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;
>
> I prefer you suppress this asymmetry with the assumption that the
> "default driver" will not register a "in_use" callback.
Based on comments by Connie, I plan on removing this patch from the
next version.
>
>
>> +
>> + /* Pin the driver's module code */
>> + 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;
>> +}
>> +
>
next prev parent reply other threads:[~2019-04-16 13:11 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-11 21:03 [PATCH 0/7] s390: vfio-ap: dynamic configuration support Tony Krowiak
2019-04-11 21:03 ` [PATCH 1/7] s390: zcrypt: driver callback to indicate resource in use Tony Krowiak
2019-04-12 6:54 ` Harald Freudenberger
2019-04-12 9:43 ` Cornelia Huck
2019-04-12 19:38 ` Tony Krowiak
2019-04-15 9:50 ` Cornelia Huck
2019-04-15 16:51 ` Tony Krowiak
2019-04-15 17:02 ` Cornelia Huck
2019-04-15 18:59 ` Halil Pasic
2019-04-15 22:43 ` Tony Krowiak
2019-04-17 15:37 ` Halil Pasic
2019-04-16 7:52 ` Pierre Morel
2019-04-16 13:11 ` Tony Krowiak [this message]
2019-04-16 13:13 ` Pierre Morel
2019-04-11 21:03 ` [PATCH 2/7] s390: vfio-ap: implement in-use callback for vfio_ap driver Tony Krowiak
2019-04-11 21:03 ` [PATCH 3/7] s390: vfio-ap: allow assignment of unavailable AP resources to mdev device Tony Krowiak
2019-04-11 21:03 ` [PATCH 4/7] s390: vfio-ap: allow hot plug/unplug of AP resources using " Tony Krowiak
2019-04-11 21:03 ` [PATCH 5/7] s390: vfio-ap: wait for queue empty on queue reset Tony Krowiak
2019-04-11 21:03 ` [PATCH 6/7] s390: vfio-ap: handle dynamic config/deconfig of AP adapter Tony Krowiak
2019-04-12 7:09 ` Harald Freudenberger
2019-04-15 9:54 ` Pierre Morel
2019-04-15 18:52 ` Tony Krowiak
2019-04-11 21:03 ` [PATCH 7/7] s390: vfio-ap: update documentation Tony Krowiak
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