Re: [PATCH v2 10/22] vfio/pci: Skip reset of preserved device after Live Update

David Matlack
2026-03-16T18:11:53Z

On Fri, Mar 13, 2026 at 8:39 AM Jacob Pan <jacob.pan@linux.microsoft.com> wrote:
> On Thu, 12 Mar 2026 23:39:45 +0000
> David Matlack <dmatlack@google.com> wrote:

> > +config VFIO_PCI_LIVEUPDATE
> > + bool "VFIO PCI support for Live Update (EXPERIMENTAL)"
> > + depends on LIVEUPDATE && VFIO_PCI
> > + help
> > + Support for preserving devices bound to vfio-pci across a
> > Live
> > + Update. The eventual goal is that preserved devices can run
> > + uninterrupted during a Live Update, including DMA to
> > preserved
> > + memory buffers and P2P. However there are many steps still
> > needed to
> > + achieve this, including:
> > +
> > + - Preservation of iommufd files
> > + - Preservation of IOMMU driver state
> In the interim, what do you think about moving forward with noiommu
> mode without preserving IOMMU driver state?

I haven't gotten a chance to look at your noiommu patches yet, but I
do think noiommu will probably be a good way to develop the VFIO and
PCI support for Live Update without blocking on IOMMU driver support.

> I’ve tested your
> vfio_pci_liveupdate_kexec_test with the noiommu cdev, and it works as
> expected.

Would you be able to send patches to add noiommu support to VFIO
selftests? That would be very helpful toward allowing us to develop
and test Live Update support with noiommu.