On Mon, 2014-09-01 at 22:55 -0700, Andy Lutomirski wrote: > > On x86, at least, I doubt that we'll ever see a physically addressed > PCI virtio device for which ACPI advertises an IOMMU, since any sane > hypervisor will just not advertise an IOMMU for the virtio device. > But are there arm64 or PPC guests that use virtio_pci, that have > IOMMUs, and that will malfunction if the virtio_pci driver ends up > using the IOMMU? I certainly hope not, since these systems might be > very hard-pressed to work right if someone plugged in a physical > virtio-speaking PCI device. It will definitely not work on ppc64. We always have IOMMUs on pseries, all PCI busses do, and because it's a paravirtualized environment, napping/unmapping pages means hypercalls -> expensive. But our virtio implementation bypasses it in qemu, so if virtio-pci starts using the DMA mapping API without changing the DMA ops under the hood, it will break for us. Cheers, Ben. -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
