Hi, On 11/18/2017 02:55 AM, Jacob Pan wrote: > 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. > > Faults detected by IOMMU is based on the transaction's source ID which > can be reported at per device basis, regardless of the device type is a > PCI device or not. > > The fault types include recoverable (e.g. page request) and > unrecoverable faults(e.g. access error). In most cases, faults can be > handled by IOMMU drivers internally. The primary use cases are as > follows: > 1. page request fault originated from an SVM capable device that is > assigned to guest via vIOMMU. In this case, the first level page tables > are owned by the guest. Page request must be propagated to the guest to > let guest OS fault in the pages then send page response. In this > mechanism, the direct receiver of IOMMU fault notification is VFIO, > which can relay notification events to QEMU or other user space > software. > > 2. faults need more subtle handling by device drivers. Other than > simply invoke reset function, there are needs to let device driver > handle the fault with a smaller impact. > > This patchset is intended to create a generic fault report API such > that it can scale as follows: > - all IOMMU types > - PCI and non-PCI devices > - recoverable and unrecoverable faults > - VFIO and other other in kernel users > - DMA & IRQ remapping (TBD) > The original idea was brought up by David Woodhouse and discussions > summarized at https://lwn.net/Articles/608914/. > > Signed-off-by: Jacob Pan <jacob.jun....@linux.intel.com> > Signed-off-by: Ashok Raj <ashok....@intel.com> > --- > drivers/iommu/iommu.c | 63 > ++++++++++++++++++++++++++++++++++++++++++++++++++- > include/linux/iommu.h | 36 +++++++++++++++++++++++++++++ > 2 files changed, 98 insertions(+), 1 deletion(-) > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index 829e9e9..97b7990 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -581,6 +581,12 @@ int iommu_group_add_device(struct iommu_group *group, > struct device *dev) > goto err_free_name; > } > > + dev->iommu_param = kzalloc(sizeof(struct iommu_fault_param), > GFP_KERNEL); > + if (!dev->iommu_param) { > + ret = -ENOMEM; > + goto err_free_name; > + } > + > kobject_get(group->devices_kobj); > > dev->iommu_group = group; > @@ -657,7 +663,7 @@ 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; > @@ -791,6 +797,61 @@ int iommu_group_unregister_notifier(struct iommu_group > *group, > } > EXPORT_SYMBOL_GPL(iommu_group_unregister_notifier); > > +int iommu_register_device_fault_handler(struct device *dev, > + iommu_dev_fault_handler_t handler, > + void *data) > +{ > + struct iommu_param *idata = dev->iommu_param; > + > + /* > + * Device iommu_param should have been allocated when device is > + * added to its iommu_group. > + */ > + if (!idata) > + return -EINVAL; > + /* Only allow one fault handler registered for each device */ > + if (idata->fault_param) > + return -EBUSY; > + get_device(dev); > + idata->fault_param = > + kzalloc(sizeof(struct iommu_fault_param), GFP_KERNEL); > + if (!idata->fault_param) > + return -ENOMEM; > + idata->fault_param->handler = handler; > + idata->fault_param->data = data; > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(iommu_register_device_fault_handler); > + > +int iommu_unregister_device_fault_handler(struct device *dev) > +{ > + struct iommu_param *idata = dev->iommu_param; > + > + if (!idata) > + return -EINVAL; > + > + kfree(idata->fault_param); > + idata->fault_param = NULL; > + put_device(dev); > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(iommu_unregister_device_fault_handler); > + > + > +int iommu_report_device_fault(struct device *dev, struct iommu_fault_event > *evt) > +{ > + /* we only report device fault if there is a handler registered */ > + if (!dev->iommu_param || !dev->iommu_param->fault_param || > + !dev->iommu_param->fault_param->handler)
Can this replaced by: if (!iommu_has_device_fault_handler(dev)) ? Best regards, Lu Baolu > + return -ENOSYS; > + > + return dev->iommu_param->fault_param->handler(evt, > + > dev->iommu_param->fault_param->data); > +} > +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 dfda89b..841c044 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -463,6 +463,14 @@ 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 *); > @@ -481,6 +489,12 @@ extern void iommu_domain_window_disable(struct > iommu_domain *domain, u32 wnd_nr) > extern int report_iommu_fault(struct iommu_domain *domain, struct device > *dev, > unsigned long iova, int flags); > > +static inline bool iommu_has_device_fault_handler(struct device *dev) > +{ > + return dev->iommu_param && dev->iommu_param->fault_param && > + dev->iommu_param->fault_param->handler; > +} > + > static inline void iommu_flush_tlb_all(struct iommu_domain *domain) > { > if (domain->ops->flush_iotlb_all) > @@ -734,6 +748,28 @@ 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 0; > +} > + > +static inline int iommu_unregister_device_fault_handler(struct device *dev) > +{ > + return 0; > +} > + > +static inline bool iommu_has_device_fault_handler(struct device *dev) > +{ > + return false; > +} > + > +static inline int iommu_report_device_fault(struct device *dev, struct > iommu_fault_event *evt) > +{ > + return 0; > +} > + > static inline int iommu_group_id(struct iommu_group *group) > { > return -ENODEV;