On Sun, 17 Mar 2019 18:22:13 +0100 Eric Auger <[email protected]> wrote:
> From: Jacob Pan <[email protected]> > > Traditionally, device specific faults are detected and handled within > their own device drivers. When IOMMU is enabled, faults such as DMA > related transactions are detected by IOMMU. There is no generic > reporting mechanism to report faults back to the in-kernel device > driver or the guest OS in case of assigned devices. > > This patch introduces a registration API for device specific fault > handlers. This differs from the existing iommu_set_fault_handler/ > report_iommu_fault infrastructures in several ways: > - it allows to report more sophisticated fault events (both > unrecoverable faults and page request faults) due to the nature > of the iommu_fault struct > - it is device specific and not domain specific. > > The current iommu_report_device_fault() implementation only handles > the "shoot and forget" unrecoverable fault case. Handling of page > request faults or stalled faults will come later. > > Signed-off-by: Jacob Pan <[email protected]> > Signed-off-by: Ashok Raj <[email protected]> > Signed-off-by: Jean-Philippe Brucker <[email protected]> > Signed-off-by: Eric Auger <[email protected]> > > --- > > v4 -> v5: > - remove stuff related to recoverable faults > --- > drivers/iommu/iommu.c | 134 +++++++++++++++++++++++++++++++++++++++++- > include/linux/iommu.h | 36 +++++++++++- > 2 files changed, 168 insertions(+), 2 deletions(-) > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index 33a982e33716..56d5bf68de53 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -648,6 +648,13 @@ int iommu_group_add_device(struct iommu_group *group, > struct device *dev) > goto err_free_name; > } > > + dev->iommu_param = kzalloc(sizeof(*dev->iommu_param), GFP_KERNEL); > + if (!dev->iommu_param) { > + ret = -ENOMEM; > + goto err_free_name; > + } > + mutex_init(&dev->iommu_param->lock); > + > kobject_get(group->devices_kobj); > > dev->iommu_group = group; > @@ -678,6 +685,7 @@ int iommu_group_add_device(struct iommu_group *group, > struct device *dev) > mutex_unlock(&group->mutex); > dev->iommu_group = NULL; > kobject_put(group->devices_kobj); > + kfree(dev->iommu_param); > err_free_name: > kfree(device->name); > err_remove_link: > @@ -724,7 +732,7 @@ void iommu_group_remove_device(struct device *dev) > sysfs_remove_link(&dev->kobj, "iommu_group"); > > trace_remove_device_from_group(group->id, dev); > - > + kfree(dev->iommu_param); > kfree(device->name); > kfree(device); > dev->iommu_group = NULL; > @@ -858,6 +866,130 @@ int iommu_group_unregister_notifier(struct iommu_group > *group, > } > EXPORT_SYMBOL_GPL(iommu_group_unregister_notifier); > > +/** > + * iommu_register_device_fault_handler() - Register a device fault handler > + * @dev: the device > + * @handler: the fault handler > + * @data: private data passed as argument to the handler > + * > + * When an IOMMU fault event is received, this handler gets called with the > + * fault event and data as argument. > + * > + * Return 0 if the fault handler was installed successfully, or an error. > + */ > +int iommu_register_device_fault_handler(struct device *dev, > + iommu_dev_fault_handler_t handler, > + void *data) > +{ > + struct iommu_param *param = dev->iommu_param; > + int ret = 0; > + > + /* > + * Device iommu_param should have been allocated when device is > + * added to its iommu_group. > + */ > + if (!param) > + return -EINVAL; > + > + mutex_lock(¶m->lock); > + /* Only allow one fault handler registered for each device */ > + if (param->fault_param) { > + ret = -EBUSY; > + goto done_unlock; > + } > + > + get_device(dev); > + param->fault_param = > + kzalloc(sizeof(struct iommu_fault_param), GFP_KERNEL); > + if (!param->fault_param) { > + put_device(dev); > + ret = -ENOMEM; > + goto done_unlock; > + } > + mutex_init(¶m->fault_param->lock); > + param->fault_param->handler = handler; > + param->fault_param->data = data; > + INIT_LIST_HEAD(¶m->fault_param->faults); > + > +done_unlock: > + mutex_unlock(¶m->lock); > + > + return ret; > +} > +EXPORT_SYMBOL_GPL(iommu_register_device_fault_handler); > + > +/** > + * iommu_unregister_device_fault_handler() - Unregister the device fault > handler > + * @dev: the device > + * > + * Remove the device fault handler installed with > + * iommu_register_device_fault_handler(). > + * > + * Return 0 on success, or an error. > + */ > +int iommu_unregister_device_fault_handler(struct device *dev) > +{ > + struct iommu_param *param = dev->iommu_param; > + int ret = 0; > + > + if (!param) > + return -EINVAL; > + > + mutex_lock(¶m->lock); > + > + if (!param->fault_param) > + goto unlock; > + > + /* we cannot unregister handler if there are pending faults */ > + if (!list_empty(¶m->fault_param->faults)) { > + ret = -EBUSY; > + goto unlock; > + } > + > + kfree(param->fault_param); > + param->fault_param = NULL; > + put_device(dev); > +unlock: > + mutex_unlock(¶m->lock); > + > + return ret; > +} > +EXPORT_SYMBOL_GPL(iommu_unregister_device_fault_handler); > + > + > +/** > + * iommu_report_device_fault() - Report fault event to device > + * @dev: the device > + * @evt: fault event data > + * > + * Called by IOMMU model specific drivers when fault is detected, typically > + * in a threaded IRQ handler. > + * > + * Return 0 on success, or an error. > + */ > +int iommu_report_device_fault(struct device *dev, struct iommu_fault_event > *evt) > +{ > + struct iommu_fault_param *fparam; > + int ret = 0; > + Nit, for consistency with above functions, it'd be useful to have: struct iommu_param *param = dev->iommu_param; It's not as obvious as it could be that we're using the same mutex here as in the register/unregister above. Thanks, Alex > + /* iommu_param is allocated when device is added to group */ > + if (!dev->iommu_param || !evt) > + return -EINVAL; > + /* we only report device fault if there is a handler registered */ > + mutex_lock(&dev->iommu_param->lock); > + if (!dev->iommu_param->fault_param || > + !dev->iommu_param->fault_param->handler) { > + ret = -EINVAL; > + goto done_unlock; > + } > + fparam = dev->iommu_param->fault_param; > + ret = fparam->handler(evt, fparam->data); > +done_unlock: > + mutex_unlock(&dev->iommu_param->lock); > + return ret; > +} > +EXPORT_SYMBOL_GPL(iommu_report_device_fault); > + > /** > * iommu_group_id - Return ID for a group > * @group: the group to ID > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index c6f398f7e6e0..aeb4b615cb44 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -257,11 +257,13 @@ struct iommu_device { > * unrecoverable faults such as DMA or IRQ remapping faults. > * > * @fault: fault descriptor > + * @list pending fault event list, used for tracking responses > * @iommu_private: used by the IOMMU driver for storing fault-specific > * data. Users should not modify this field before > * sending the fault response. > */ > struct iommu_fault_event { > + struct list_head list; > struct iommu_fault fault; > u64 iommu_private; > }; > @@ -270,10 +272,13 @@ struct iommu_fault_event { > * struct iommu_fault_param - per-device IOMMU fault data > * @dev_fault_handler: Callback function to handle IOMMU faults at device > level > * @data: handler private data > - * > + * @faults: holds the pending faults which needs response, e.g. page > response. > + * @lock: protect pending PRQ event list > */ > struct iommu_fault_param { > iommu_dev_fault_handler_t handler; > + struct list_head faults; > + struct mutex lock; > void *data; > }; > > @@ -287,6 +292,7 @@ struct iommu_fault_param { > * struct iommu_fwspec *iommu_fwspec; > */ > struct iommu_param { > + struct mutex lock; > struct iommu_fault_param *fault_param; > }; > > @@ -379,6 +385,15 @@ extern int iommu_group_register_notifier(struct > iommu_group *group, > struct notifier_block *nb); > extern int iommu_group_unregister_notifier(struct iommu_group *group, > struct notifier_block *nb); > +extern int iommu_register_device_fault_handler(struct device *dev, > + iommu_dev_fault_handler_t handler, > + void *data); > + > +extern int iommu_unregister_device_fault_handler(struct device *dev); > + > +extern int iommu_report_device_fault(struct device *dev, > + struct iommu_fault_event *evt); > + > extern int iommu_group_id(struct iommu_group *group); > extern struct iommu_group *iommu_group_get_for_dev(struct device *dev); > extern struct iommu_domain *iommu_group_default_domain(struct iommu_group *); > @@ -659,6 +674,25 @@ static inline int iommu_group_unregister_notifier(struct > iommu_group *group, > return 0; > } > > +static inline > +int iommu_register_device_fault_handler(struct device *dev, > + iommu_dev_fault_handler_t handler, > + void *data) > +{ > + return -ENODEV; > +} > + > +static inline int iommu_unregister_device_fault_handler(struct device *dev) > +{ > + return 0; > +} > + > +static inline > +int iommu_report_device_fault(struct device *dev, struct iommu_fault_event > *evt) > +{ > + return -ENODEV; > +} > + > static inline int iommu_group_id(struct iommu_group *group) > { > return -ENODEV; _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
