Re: [virtio-comment] Re: [PATCH v1 3/8] device-context: Define the device context fields for device migration

["Zhu, Lingshan" <lingshan.zhu@intel.com>]

On 10/13/2023 9:49 PM, Michael S. Tsirkin wrote:
> On Fri, Oct 13, 2023 at 05:44:27PM +0800, Zhu, Lingshan wrote:
> > > As Michael said, software based nesting is used..
> > > See if actual hw based devices can implement it or not. Many components of cpu cannot do N level nesting either, but may be virtio can.
> > > I donât know how yet.
> > two facts:
> > 1. virito works for nested for years
> > 2. your admin vq lm solution does not work for nested
> First virtio works but nested migration doesn't: the way virtio works doesn't
> allow L1 hypervisor to migrate L2 if it passes virtio through to L2,
> except by using full emulation approaches such as shadow vq -
> surely, these are still possible.
hope our live migration basic facilities can help resolve these problems.
> Second doesn't work is an overstatement.  It remains to be seen what else can
> be done though.  You hinted at a depdenency on PASID.  Have owner be a
> PASID and Parav's approach seems to work with little to no change.
for nested, it requires vIOMMU for sure.
>