On 2/25/23 8:27 AM, Jason Gunthorpe wrote:
+/**
+ * iommufd_device_attach - Connect a device to an iommu_domain
+ * @idev: device to attach
+ * @pt_id: Input a IOMMUFD_OBJ_IOAS, or IOMMUFD_OBJ_HW_PAGETABLE
+ * Output the IOMMUFD_OBJ_HW_PAGETABLE ID
"Output the hwpt ID" only happens when the caller input an IOAS object
and an auto domain was selected or created for the device.
Do I understand it right?
+ *
+ * This connects the device to an iommu_domain, either automatically or manually
+ * selected. Once this completes the device could do DMA.
+ *
+ * The caller should return the resulting pt_id back to userspace.
+ * This function is undone by calling iommufd_device_detach().
+ */
+int iommufd_device_attach(struct iommufd_device *idev, u32 *pt_id)
+{
+ int rc;
+
+ rc = iommufd_device_change_pt(idev, pt_id, &iommufd_device_do_attach);
+ if (rc)
+ return rc;
+
+ /*
+ * Pairs with iommufd_device_detach() - catches caller bugs attempting
+ * to destroy a device with an attachment.
+ */
+ refcount_inc(&idev->obj.users);
+ return 0;
}
EXPORT_SYMBOL_NS_GPL(iommufd_device_attach, IOMMUFD);
+/**
+ * iommufd_device_replace - Change the device's iommu_domain
+ * @idev: device to change
+ * @pt_id: Input a IOMMUFD_OBJ_IOAS, or IOMMUFD_OBJ_HW_PAGETABLE
+ * Output the IOMMUFD_OBJ_HW_PAGETABLE ID
If my above understanding is correct, then replace will never output a
hwpt id as it only happens after a successful attach.
+ *
+ * This is the same as:
+ * iommufd_device_detach();
+ * iommufd_device_attach()
+ * If it fails then no change is made to the attachment. The iommu driver may
+ * implement this so there is no disruption in translation. This can only be
+ * called if iommufd_device_attach() has already succeeded.
+ */
+int iommufd_device_replace(struct iommufd_device *idev, u32 *pt_id)
+{
+ return iommufd_device_change_pt(idev, pt_id,
+ &iommufd_device_do_replace);
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_device_replace, IOMMUFD);
Best regards,
baolu
