Re: [PATCH v5 2/3] virtio_pci: Use the DMA API for virtqueues when possible

Benjamin Herrenschmidt
2014-09-29T21:06:22Z

On Mon, 2014-09-29 at 13:55 -0700, Andy Lutomirski wrote:
> If the eventual solution is to say that virtio 1.0 PCI devices always
> respect an IOMMU unless they set a magic flag saying "I'm not real
> hardware and I bypass the IOMMU", then I don't really object to that,
> except that it'll be a mess if the guest is running Xen. But even Xen
> would (I think) be okay if it actually worked by having a new DMA API
> operation that says "this device is magically identity mapped" and
> then just teaching Xen to implement that.
>
> But I'm not an OASIS member, so I can't really do this. I agree that
> this issue needs to be addressed somehow, but I don't think it needs
> to block these patches.

I'll let Rusty be the final judge of that (well, when he's back from his
vacation that is).

Cheers,
Ben.