Re: [Qemu-devel] [PATCH v2] virtio-pci: Don't force Subsystem Vendor ID = Vendor ID

[Gerd Hoffmann]

On Mon, Nov 13, 2017 at 09:45:58AM +0100, Ladi Prosek wrote:
> The statement being removed doesn't change anything as virtio PCI devices 
> already
> have Subsystem Vendor ID set to pci_default_sub_vendor_id (0x1af4), same as 
> Vendor
> ID. And the Virtio spec does not require the two to be equal, either:
> 
>   "The PCI Subsystem Vendor ID and the PCI Subsystem Device ID MAY reflect 
> the PCI
>   Vendor and Device ID of the environment (for informational purposes by the 
> driver)."
> 
> Background:
> 
> Following the recent virtio-win licensing change, several vendors are 
> planning to
> ship their own certified version of Windows guest Virtio drivers, potentially 
> taking
> advantage of Windows Update as a distribution channel. It is therefore 
> critical that
> each vendor uses their own PCI Subsystem Vendor ID for Virtio devices to 
> prevent
> drivers from other vendors binding to it.
> 
> This would be trivially done by adding:
> 
>   k->subsystem_vendor_id = ...
> 
> to virtio_pci_class_init(). Except for the problematic statement deleted by 
> this
> patch, which reverts the Subsystem Vendor ID back to 0x1af4 for legacy 
> devices for
> no good reason.

Reviewed-by: Gerd Hoffmann <address@hidden>

cheers,
  Gerd