RE: [PATCH v6,1/2] PCI: hv: Detect and fix Hyper-V PCI domain number collision

[Haiyang Zhang]

> -----Original Message-----
> From: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> Sent: Friday, August 16, 2019 5:52 AM
> To: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> Cc: sashal@xxxxxxxxxx; bhelgaas@xxxxxxxxxx; linux-
> hyperv@xxxxxxxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx; KY Srinivasan
> <kys@xxxxxxxxxxxxx>; Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>;
> olaf@xxxxxxxxx; vkuznets <vkuznets@xxxxxxxxxx>; linux-
> kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v6,1/2] PCI: hv: Detect and fix Hyper-V PCI domain
> number collision
> 
> On Thu, Aug 15, 2019 at 05:01:37PM +0000, Haiyang Zhang wrote:
> > Currently in Azure cloud, for passthrough devices, the host sets the
> > device instance ID's bytes 8 - 15 to a value derived from the host
> > HWID, which is the same on all devices in a VM. So, the device
> > instance ID's bytes 8 and 9 provided by the host are no longer unique.
> > This affects all Azure hosts since July 2018, and can cause device
> > passthrough to VMs to fail because the bytes 8 and 9 are used as PCI
> > domain number. Collision of domain numbers will cause the second
> > device with the same domain number fail to load.
> >
> > In the cases of collision, we will detect and find another number that
> > is not in use.
> >
> > Suggested-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
> > Signed-off-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> > Acked-by: Sasha Levin <sashal@xxxxxxxxxx>
> 
> I assume you will take care of backporting and sending this patch to stable
> kernels given that you have not applied any tag with such request.
> 
> I appreciate it may not be easy to define but a Fixes: tag would help.

Sure, I will add a Fixes tag, and Cc stable. Usually Sasha from our team will
do the stable porting in batches.

Thanks,
- Haiyang