Re: [PATCH v3 0/3] virtio DMA API core stuff
From: Michael S. Tsirkin
Date: Mon Nov 23 2015 - 02:57:11 EST
On Sun, Nov 22, 2015 at 10:21:34PM -0000, David Woodhouse wrote:
> > There's that, and there's an "I care about security, but
> > do not want to burn up cycles on fake protections that
> > do not work" case.
> It would seem to make most sense for this use case simply *not* to expose
> virtio devices to guests as being behind an IOMMU at all. Sure, there are
> esoteric use cases where the guest actually nests and runs further guests
> inside itself and wants to pass through the virtio devices from the real
> hardware host. But presumably those configurations will have multiple
> virtio devices assigned by the host anyway, and further tweaking the
> configuration to put them behind an IOMMU shouldn't be hard.
Unfortunately it's a no-go: this breaks the much less esoteric usecase
of DPDK: using virtio devices with userspace drivers.
Well - not breaks as such as this doesn't currently work,
but this approach would prevent us from making it work.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/