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

Jacob Pan
2026-03-19T16:28:41Z

Hi Vipin,

On Mon, 16 Mar 2026 09:28:32 -0700
Vipin Sharma <vipinsh@google.com> wrote:

> On Fri, Mar 13, 2026 at 08:39:18AM -0700, Jacob Pan wrote:
> > Hi David,
> >
> > > +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’ve tested your
> > vfio_pci_liveupdate_kexec_test with the noiommu cdev, and it works
> > as expected.
> >
>
> Just curious, are you using qemu VM without iommu device for noiommu
> work or do you have actual system without iommu hardware for testing?

I am using a qemu VM without iommu device and with an assigned
nvme device. I use a low level nvme userspace driver (modified to use
iommufd noiommu mode) for testing.