On Thu, Oct 11, 2012 at 03:34:54PM +0200, Avi Kivity wrote: > On 10/11/2012 03:31 PM, Michael S. Tsirkin wrote: > > On Thu, Oct 11, 2012 at 03:27:03PM +0200, Avi Kivity wrote: > >> vhost doesn't support guest iommus yet, indicate it to the user > >> by gently depositing a core on their disk. > >> > >> Signed-off-by: Avi Kivity <a...@redhat.com> > > > > Actually there is no problem. virtio bypasses an IOMMU, > > so vhost works fine by writing into guest memory directly. > > > > So I don't think we need this patch. > > The pci subsystem should set up the iommu so that it ignores virtio > devices. If it does, an emulated iommu will not reach vhost. If it > doesn't, then it will, and the assert() will alert us that we have a bug.
You mean pci subsystem in the guest? I'm pretty sure that's not the case at the moment: iommu is on by default and applies to all devices unless you do something special. I see where you are coming from but it does not look right to break all existing guests. Also - I see no reason to single out vhost - I think same applies with any virtio device, since it doesn't use the DMA API. > > -- > error compiling committee.c: too many arguments to function
