From 0c830e6b32826311fc2b9ea1f4679be0f4ef0933 Mon Sep 17 00:00:00 2001 From: Jacob Pan Date: Mon, 3 Jun 2019 15:57:48 +0100 Subject: iommu: Introduce device fault report API 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 Signed-off-by: Ashok Raj Signed-off-by: Jean-Philippe Brucker Signed-off-by: Eric Auger Signed-off-by: Joerg Roedel --- drivers/iommu/iommu.c | 146 ++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 143 insertions(+), 3 deletions(-) (limited to 'drivers/iommu/iommu.c') diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 3fa025f849e9..293a6fa716e0 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -107,15 +107,43 @@ void iommu_device_unregister(struct iommu_device *iommu) spin_unlock(&iommu_device_lock); } +static struct iommu_param *iommu_get_dev_param(struct device *dev) +{ + struct iommu_param *param = dev->iommu_param; + + if (param) + return param; + + param = kzalloc(sizeof(*param), GFP_KERNEL); + if (!param) + return NULL; + + mutex_init(¶m->lock); + dev->iommu_param = param; + return param; +} + +static void iommu_free_dev_param(struct device *dev) +{ + kfree(dev->iommu_param); + dev->iommu_param = NULL; +} + int iommu_probe_device(struct device *dev) { const struct iommu_ops *ops = dev->bus->iommu_ops; - int ret = -EINVAL; + int ret; WARN_ON(dev->iommu_group); + if (!ops) + return -EINVAL; - if (ops) - ret = ops->add_device(dev); + if (!iommu_get_dev_param(dev)) + return -ENOMEM; + + ret = ops->add_device(dev); + if (ret) + iommu_free_dev_param(dev); return ret; } @@ -126,6 +154,8 @@ void iommu_release_device(struct device *dev) if (dev->iommu_group) ops->remove_device(dev); + + iommu_free_dev_param(dev); } static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus, @@ -854,6 +884,116 @@ 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. The handler should return 0 on success. + * + * 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; + + 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(*param->fault_param), GFP_KERNEL); + if (!param->fault_param) { + put_device(dev); + ret = -ENOMEM; + goto done_unlock; + } + param->fault_param->handler = handler; + param->fault_param->data = data; + +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; + + 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 driver + * @dev: the device + * @evt: fault event data + * + * Called by IOMMU drivers when a 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_param *param = dev->iommu_param; + struct iommu_fault_param *fparam; + int ret = 0; + + if (!param || !evt) + return -EINVAL; + + /* we only report device fault if there is a handler registered */ + mutex_lock(¶m->lock); + fparam = param->fault_param; + if (!fparam || !fparam->handler) { + ret = -EINVAL; + goto done_unlock; + } + ret = fparam->handler(&evt->fault, fparam->data); +done_unlock: + mutex_unlock(¶m->lock); + return ret; +} +EXPORT_SYMBOL_GPL(iommu_report_device_fault); + /** * iommu_group_id - Return ID for a group * @group: the group to ID -- cgit v1.2.3