Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready

[Michael S. Tsirkin]

On Mon, Oct 26, 2020 at 05:45:37PM +1100, David Gibson wrote:
> On Fri, 23 Oct 2020 09:26:48 +0300
> Marcel Apfelbaum <marcel.apfelbaum@gmail.com> wrote:
> 
> > Hi Michael,
> > 
> > On Thu, Oct 22, 2020 at 6:01 PM Michael S. Tsirkin <mst@redhat.com> wrote:
> > 
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> > Simplistic does not mean wrong or incorrect.
> > I fail to see why it is not enough.
> > 
> > What QEMU can do better? Wait an unbounded time for the blinking to finish?
> 
> It certainly shouldn't wait an unbounded time.  But a wait with timeout
> seems worth investigating to me.

If it's helpful, I'd add a query to check state
so management can figure out why doesn't guest see device yet.
But otherwise just buffer the request until such time as
we can deliver it to guest ...


> > What if we have a buggy guest with a kernel stuck in blinking?
> > Is QEMU's responsibility to emulate the operator itself? Because the
> > operator
> > is the one who is supposed to wait.
> > 
> > 
> > Thanks,
> > Marcel
> > 
> > [...]
> 
> 
> -- 
> David Gibson <dgibson@redhat.com>
> Principal Software Engineer, Virtualization, Red Hat