Hi Alex, I've been looking at device passthrough for platform devices on x86 that are not behind an IOMMU by virtue of not being DMA masters. I think on some level this is an explicit non-goal of VFIO (https://www.spinics.net/lists/linux-renesas-soc/msg26153.html , https://blog.linuxplumbersconf.org/2014/wp-content/uploads/2014/10/LPC2014_IOMMU.txt)? >From my understanding VFIO is mostly about IOMMU management. I have a few questions however:
1) Are interrupt forwarding, IOMMU mgmt, and PCI config space virtualization the main 3 things that VFIO does (plus some hacks to get GPUs working in guests)? Would you add any other aspects of VFIO that I'm missing? 2) If you can forward interrupts to a guest without VFIO (say with something like this patch: https://www.spinics.net/lists/kvm/msg207949.html), then it should be pretty simple to configure the VMM to make the MMIO regions of the platform device available to the guest. Is VFIO in the loop at all for actually giving the guest access to the MMIOs or is that just done by mappings in the VMM? *I don't think I care about VFIO virtualizing PCI BARs for the guest since I would be telling the guest about the platform devices through ACPI -- so the guest wouldn't be looking to the PCI config space for that info anyway. I guess one thing to worry about here would be any dependencies the assigned platform device has on any other platform devices in the system that don't get assigned to the guest. 3) Are PCI devices always DMA masters, or at least are they always put in an IOMMU group? Have you seen cases of PCI devices that were not assignable to a guest through vfio-pci because they weren't in an IOMMU group and/or weren't DMA masters? Thanks! Micah _______________________________________________ vfio-users mailing list vfio-users@redhat.com https://www.redhat.com/mailman/listinfo/vfio-users
