[PATCH v2 07/11] video/aperture: Disable and unregister sysfb devices via aperture helpers

[Javier Martinez Canillas]

Thomas Zimmermann <tzimmermann at suse.de> writes:

[...]

>>> +    /*
>>> +     * If a driver asked to unregister a platform device registered by
>>> +     * sysfb, then can be assumed that this is a driver for a display
>>> +     * that is set up by the system firmware and has a generic driver.
>>> +     *
>>> +     * Drivers for devices that don't have a generic driver will never
>>> +     * ask for this, so let's assume that a real driver for the display
>>> +     * was already probed and prevent sysfb to register devices later.
>>> +     */
>>> +    sysfb_disable();
>> 
>> This call to sysfb_disable() has been causing trouble with regard to
>> VFIO. VFIO has been calling aperture_remove_conflicting_pci_devices to
>> get rid of any console drivers (d173780620792c) using the device in
>> question, but now even unrelated drivers are getting killed. Example
>> situation:
>
> Which drivers do you use?
>

Also, what kernel version?

[...]

>> 
>> Machine has two GPUs and uses efifb for the console. Efifb registers
>> with the aperture system the efi framebuffer region, which is covered
>> by a BAR resource of GPU 1. VFIO grabs GPU 2 and calls
>> aperture_remove_conflicting_pci_devices(GPU 2). GPU 2 has no overlap
>> with the efifb on GPU1 but the efifb is killed regardless due to
>> the unconditional call to sysfb_disable(). The console switches
>> to dummy and locks up from the user perspective.
>> This seems unnecessary, as the device is unrelated.
>> 

That's a bug indeed but I thought that was already fixed...

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat