Re: [PATCH v4 0/4] virtio: Clean up scatterlists and use the DMA API

Andy Lutomirski
2014-09-03T07:52:18Z

On Wed, Sep 3, 2014 at 12:47 AM, Paolo Bonzini <pbonzini@redhat.com> wrote:
> Il 03/09/2014 02:25, Benjamin Herrenschmidt ha scritto:
>> > But there aren't any ACPI systems with both virtio-pci and IOMMUs,
>> > right? So we could say that, henceforth, ACPI systems must declare
>> > whether virtio-pci devices live behind IOMMUs without breaking
>> > backward compatibility.
>>
>> I don't know for sure whether that's the case and whether we can rely on
>> that not happening, we'll need x86 folks opinion here.
>
> IOMMU support for x86 is going to go in this week.
>

Can you try to make sure that qemu-system-x86_64 -device iommu -device
virtio-balloon-pci (or whatever the syntax is) doesn't put the
virtio-pci device behind the IOMMU? Because, if it does, then the
kernel will have to support that, and it'll be messy.

--Andy