On Wed, Sep 03, 2014 at 06:53:33AM +1000, Benjamin Herrenschmidt wrote: > 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. What is the default dma_ops that the Linux guests start with as guests under ppc64? Thanks! > > 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
