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On server platforms, DMAR DRHD device scope entries may contain PCI bridges. Bridges in the DRHD device scope indicate this IOMMU translates for all devices on the hierarchy below that bridge. ACRN is unaware of bridge types in the device scope, and adds these directly to its internal representation of a DRHD. When looking up a BDF within these DRHD entries, device_to_dmaru assumes all entries are Endpoints, comparing BDF to BDF. Thus device to DMAR unit fails, because it treats a bridge as an Endpoint type. This change leverages prior patches by converting a BDF to the associated device DRHD index, and uses that index to obtain the correct DRHD state. Handling a bridge in other ways may require maintaining a bus list for each, or replacing each bridge in the dev scope with a set of all device BDFs underneath it. Server platforms can have hundreds of PCI devices, thus making the device scope artificially large is unwieldy. Tracked-On: #4134 Signed-off-by: Alexander Merritt <alex.merritt@intel.com> Reviewed-by: Eddie Dong <eddie.dong@intel.com> Reviewed-by: Jason Chen CJ <jason.cj.chen@intel.com>
ACRN Hypervisor ############### The open source `Project ACRN`_ defines a device hypervisor reference stack and an architecture for running multiple software subsystems, managed securely, on a consolidated system by means of a virtual machine manager. It also defines a reference framework implementation for virtual device emulation, called the "ACRN Device Model". The ACRN Hypervisor is a Type 1 reference hypervisor stack, running directly on the bare-metal hardware, and is suitable for a variety of IoT and embedded device solutions. The ACRN hypervisor addresses the gap that currently exists between datacenter hypervisors, and hard partitioning hypervisors. The ACRN hypervisor architecture partitions the system into different functional domains, with carefully selected guest OS sharing optimizations for IoT and embedded devices. You can find out more about Project ACRN on the `Project ACRN documentation`_ website. .. _`Project ACRN`: https://projectacrn.org .. _`ACRN Hypervisor`: https://github.com/projectacrn/acrn-hypervisor .. _`Project ACRN documentation`: https://projectacrn.github.io/