Messages in this thread | | | Subject | Re: [PATCH 1/7] s390: zcrypt: driver callback to indicate resource in use | From | Tony Krowiak <> | Date | Tue, 16 Apr 2019 09:11:19 -0400 |
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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; >> +} >> + >
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