ACS Enhanced Capabilities

This ECN defines four new services under ACS for Downstream Ports, primarily to address issues when ACS redirect mechanisms are used to ensure that DMA Requests from Functions under the direct control of VMs are always routed correctly to the Translation Agent in the host. Three of the services provide redirect or blocking of Upstream Memory Requests that target areas not covered by other ACS services. The fourth service enables the blocking of Upstream I/O Requests, addressing a concern with VM-controlled Functions maliciously sending I/O Requests.