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Device Passthrough
To directly assign a PCI device to a PD, the IOMMU must be enabled via the microhypervisor command line. Without IOMMU there would be no guest-physical to host-physical address translation and no protection against erroneous DMA.
Furthermore, the PD to which the device is assigned must have all BARs (MMIO and IO) of the PCI device mapped. For some devices the virtual PCI requester ID (vRID) must be configured to be identical to the physical PCI requester ID (RID), because we found that some PCI option ROMs have the RID hardcoded. The same may be true for the BARs.
In addition to the PCI BARs, graphics cards typically require additional passthrough access to the legacy VGA ROM (video BIOS). Because there is no PCI BAR covering this region, it must be manually specified.
Intel Integrated Graphics additionally requires passthrough access to the LPC controller (ISA bridge) to determine the physical hardware chipset type, and to the IGD OpRegion, which is a memory region shared between firmware and the graphics driver.