Re: [PATCH v1 2/4] drm/hyperv: Explicitly set subvendor and subdevice for pci match array

Hi

Am 02.07.26 um 10:52 schrieb Uwe Kleine-König (The Capable Hub):
> Hallo Thomas,
>
> On Thu, Jul 02, 2026 at 08:43:32AM +0200, Thomas Zimmermann wrote:
>> Am 01.07.26 um 19:05 schrieb Uwe Kleine-König (The Capable Hub):
>>> .subvendor and .subdevice were set to 0 implicitly, so only devices with
>>> these two values set to 0 in hardware can probe automatically. Make this
>>> requirement explicit.
>>>
>>> While touching this array item, also make use of the pci macro designed
>>> for that case.
>>>
>>> Signed-off-by: Uwe Kleine-König (The Capable Hub) <[email protected]>
>>> ---
>>>    drivers/gpu/drm/hyperv/hyperv_drm_drv.c | 4 ++--
>>>    1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_drv.c b/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
>>> index 2e75fb793495..e766d87b7a9d 100644
>>> --- a/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
>>> +++ b/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
>>> @@ -51,8 +51,8 @@ static void hv_drm_pci_remove(struct pci_dev *pdev)
>>>    static const struct pci_device_id hv_drm_pci_tbl[] = {
>>>    	{
>>> -		.vendor = PCI_VENDOR_ID_MICROSOFT,
>>> -		.device = PCI_DEVICE_ID_HYPERV_VIDEO,
>>> +		PCI_VDEVICE_SUB(MICROSOFT, PCI_DEVICE_ID_HYPERV_VIDEO,
>>> +				0, 0),
>> IDK, but it looks like an oversight to me.  Setting the sub-fields to ANY
>> seems like the better fix.
> That was my initial reflex, too. However while writing the commit log
> for that change I noticed that since commit d750785f305e ("Staging: hv:
> fix hv_utils module to properly autoload") from 2010 (applied to
> v2.6.35-rc4) the driver never worked for hardware with .subvendor != 0
> or .subdevice != 0. I cannot believe that something like that is
> discovered 16 years later by chance during a rework by someone who
> didn't try to run that hardware. And if I understand correctly, this is
> emulated hardware and so I guess used quite a lot.

I wouldn't be surprised. To my knowledge, there's just one 
implementation of this device, which is Windows. If they clear their 
host-side structures to 0 and pass them to the guest, no one would ever 
notice the issue. But let's see what the driver maintainers can comment 
on the issue.

Best regards
Thomas

>
> Best regards
> Uwe

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)