Hi, On Tue, Feb 23, 2021 at 10:06:15PM +0100, Eric Auger wrote: > This patch adds the VFIO_IOMMU_SET_MSI_BINDING ioctl which aim > to (un)register the guest MSI binding to the host. This latter > then can use those stage 1 bindings to build a nested stage > binding targeting the physical MSIs. Now that RMR is in the IORT spec, could it be used for the nested MSI problem? For virtio-iommu tables I was planning to do it like this: MSI is mapped at stage-2 with an arbitrary IPA->doorbell PA. We report this IPA to userspace through iommu_groups/X/reserved_regions. No change there. Then to the guest we report a reserved identity mapping at IPA (using RMR, an equivalent DT binding, or probed RESV_MEM for virtio-iommu). The guest creates that mapping at stage-1, and that's it. Unless I overlooked something we'd only reuse existing infrastructure and avoid the SET_MSI_BINDING interface. Thanks, Jean _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
