Re: Problem with PCI-passthrough to PV guest

["Roger Pau Monné" <roger.pau@citrix.com>]

On Wed, May 06, 2026 at 10:45:49AM +0200, Jürgen Groß wrote:
> On 05.05.26 20:47, Roger Pau Monné wrote:
> > On Tue, May 05, 2026 at 05:53:31PM +0200, Jürgen Groß wrote:
> > > SUSE QA is seeing a problem with PCI-passthrough of a SR-IOV to a PV guest
> > > running a 6.4 based kernel, but I can reproduce the problem with upstream
> > > kernel, too.
> 
> Uh, seems my tested kernel was only "nearly upstream" (it was an early
> 7.0 kernel). It was missing commit 0949c646d646, which makes the difference.
> 
> So for now this issue will only show up for cases where a PV-guest is
> setup for PCI passthrough and it gets memory hotplugged before the PCI
> device is added to it.

Hm, yes, this is yet more fallout from the unpopulated-alloc changes.
For PV guests that have the e820 host available we could try to create
the hotplug regions over what are host RAM region in the memory map,
as then we know we won't be overlapping with MMIO areas.

Thanks, Roger.