Re: [PATCH v2 03/10] PCI/LUO: Forward prepare()/freeze()/cancel() callbacks to driver

[David Matlack]

On Fri, Oct 3, 2025 at 10:49 AM Chris Li <chrisl@xxxxxxxxxx> wrote:
>
> On Fri, Oct 3, 2025 at 5:26 AM Greg Kroah-Hartman
> <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> >
> > On Fri, Oct 03, 2025 at 12:26:01AM -0700, Chris Li wrote:
> >
> > > It is more than just one driver, we have vfio-pci, idpf, pci-pf-stub
> > > and possible nvme driver.
> >
> > Why is nvme considered a "GPU" that needs context saved?
>
> NVME is not a GPU. The internal reason to have NVME participate in the
> liveupdate is because the NVME shutdown of the IO queue is very slow,
> it contributes the largest chunk of delay in the black out window for
> liveupdate. The NVME participation is just an optimization to avoid
> resetting the NVME queue. Consider it as (optional ) speed
> optimization.

This is not true. We haven't made any changes to the nvme driver
within Google for Live Update.

The reason I mentioned nvme in another email chain is because Google
has some hosts where we want to preserve VFs bound to vfio-pci across
Live Update where the PF is bound to nvme. But Jason is suggesting we
seriously explore switching the PF driver to vfio-pci before trying to
upstream nvme support for Live Update, which I think is fair.