> From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> > Sent: Tuesday, January 30, 2024 4:09 PM > * > - * Caller makes sure that no more faults are reported for this device. > + * Removing a device from an iopf_queue. It's recommended to follow > these > + * steps when removing a device: > * > - * Return: 0 on success and <0 on error. > + * - Disable new PRI reception: Turn off PRI generation in the IOMMU > hardware > + * and flush any hardware page request queues. This should be done > before > + * calling into this helper. this 1st step is already not followed by intel-iommu driver. The Page Request Enable (PRE) bit is set in the context entry when a device is attached to the default domain and cleared only in intel_iommu_release_device(). but iopf_queue_remove_device() is called when IOMMU_DEV_FEAT_IOPF is disabled e.g. when idxd driver is unbound from the device. so the order is already violated. > + * - Acknowledge all outstanding PRQs to the device: Respond to all > outstanding > + * page requests with IOMMU_PAGE_RESP_INVALID, indicating the device > should > + * not retry. This helper function handles this. > + * - Disable PRI on the device: After calling this helper, the caller could > + * then disable PRI on the device. intel_iommu_disable_iopf() disables PRI cap before calling this helper. > + * - Tear down the iopf infrastructure: Calling iopf_queue_remove_device() > + * essentially disassociates the device. The fault_param might still exist, > + * but iommu_page_response() will do nothing. The device fault parameter > + * reference count has been properly passed from > iommu_report_device_fault() > + * to the fault handling work, and will eventually be released after > + * iommu_page_response(). it's unclear what 'tear down' means here.
