# Re: \[PATCH\] PCI: hv: Detect and fix Hyper-V PCI domain number collision

- From: Sasha Levin \<sashal@kernel.org\>
- Date: 2019-08-05 18:37:00 
- List: linux-hyperv
- Page: https://ratatoskr.run/linux-hyperv/2019/08/5678736
- Thread: https://ratatoskr.run/linux-hyperv/2019/08/5677021/t.md

```text
On Fri, Aug 02, 2019 at 06:52:56PM +0000, Haiyang Zhang wrote:
>Due to Azure host agent settings, the device instance ID's bytes 8 and 9
>are no longer unique. This causes some of the PCI devices not showing up
>in VMs with multiple passthrough devices, such as GPUs. So, as recommended
>by Azure host team, we now use the bytes 4 and 5 which usually provide
>unique numbers.
>
>In the rare cases of collision, we will detect and find another number
>that is not in use.
>Thanks to Michael Kelley [ref] for proposing this idea.
>
>Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>

Acked-by: Sasha Levin <sashal@kernel.org>

Bjorn, will you take it through the PCI tree or do you want me to take
it through hyper-v?

--
Thanks,
Sasha
```