Created attachment 330942 [details]
avoid redundant context mapping

Description of patch:

In case DEV_TYPE_PCI in domain_context_mapping(), redundant context
mapping may occur for some devices.
                                                                                For example, the NIC is 03:00.0, and its parent bridge is: 00:1e.0.
After domain_context_mapping_one() 03:00.0 and 00:1e.0, the
'secbus' is 3 and 'bus' is 0, so will domain_context_mapping_one()
03:00.0 again -- this redundant invocation returns -EINVAL because
we have created the mapping but haven't changed pdev->domain from
Dom0 to a new domain at this time and eventually the
XEN_DOMCTL_assign_device hypercall returns a failure.
 
This patch detects this case and avoids the redundant invocation.


Upstream Status: Accepted (CS 18964)