Hi Jacob, On 06/10/17 00:03, 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> > --- [...] > +int iommu_register_device_fault_handler(struct device *dev, > + iommu_dev_fault_handler_t handler) > +{ > + if (dev->iommu_fault_param) > + return -EBUSY; > + get_device(dev); > + dev->iommu_fault_param = > + kzalloc(sizeof(struct iommu_fault_param), GFP_KERNEL); > + if (!dev->iommu_fault_param) > + return -ENOMEM; > + dev->iommu_fault_param->dev_fault_handler = handler;
Since the handler is owned by a device driver, you also need to clean it up when switching the driver (native->VFIO and VFIO->native), in iommu_attach_device I suppose. Thanks, Jean _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
