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

[Ani Sinha]

+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.