Re: Failure of hot plugging secondary virtio_blk into q35 Windows 2019

[Daniel P . Berrangé]

On Tue, Nov 09, 2021 at 04:40:10PM +0530, Ani Sinha wrote:
> On Tue, Nov 9, 2021 at 3:23 PM Daniel P. Berrangé <berrange@redhat.com> wrote:
> >
> > On Tue, Nov 09, 2021 at 12:41:39PM +0530, Ani Sinha wrote:
> > >
> > > +gerd
> > >
> > > On Mon, 8 Nov 2021, Annie.li wrote:
> > >
> > > > Update:
> > > >
> > > > I've tested q35 guest w/o OVMF, the APCI PCI hot-plugging works well in 
> > > > q35
> > > > guest. Seems this issue only happens in q35 guest w/ OVMF.
> > > >
> > > > Looks that there is already a bug filed against this hotplug issue in 
> > > > q35
> > > > guest w/ OVMF,
> > > >
> > > > https://bugzilla.redhat.com/show_bug.cgi?id=2004829
> > > >
> > > > In this bug, it is recommended to add "-global
> > > > ICH9-LPC.acpi-pci-hotplug-with-bridge-support=off \" on qemu command 
> > > > for 6.1.
> > > > However, with this option for 6.1(PCIe native hotplug), there still are 
> > > > kinds
> > > > of issues. For example, one of them is the deleted virtio_blk device 
> > > > still
> > > > shows in the Device Manager in Windows q35 guest, the operation of 
> > > > re-scanning
> > > > new hardware takes forever there. This means both PCIe native hotplug 
> > > > and ACPI
> > > > hotplug all have issues in q35 guests.
> > >
> > > This is sad.
> > >
> > > >
> > > > Per comments in this bug, changes in both OVMF and QEMU are necessary to
> > > > support ACPI hot plug in q35 guest. The fixes may likely be available 
> > > > in QEMU
> > > > 6.2.0.
> > >
> > > So we are in soft code freeze for 6.2:
> > > https://wiki.qemu.org/Planning/6.2
> > >
> > > I am curious about Gerd's comment #10:
> > > "The 6.2 rebase should make hotplug work
> > > again with the default configuration."
> > >
> > > Sadly I have not seen any public discussion on what we want to do
> > > for the issues with acpi hotplug for bridges in q35.
> >
> > I've raised one of the problems a week ago and there's a promised
> > fix
> >
> >  https://lists.gnu.org/archive/html/qemu-devel/2021-11/msg00558.html
> 
> So https://gitlab.com/qemu-project/qemu/-/issues/641 is the same as
> https://bugzilla.redhat.com/show_bug.cgi?id=2006409
> 
> isn't it?

Yes, one upstream, one downstream.

Regards,
Daniel
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