Re: [pve-devel] [PATCH qemu-server v2 12/13] fix #3574: enable multi pci device mapping from config

[Dominik Csapak <d.csapak@proxmox.com>]

On 8/25/22 16:53, DERUMIER, Alexandre wrote:
>   > root@pve2:~# qm start 101
>   > ignoring mediated device with multifunction device
> 
> ok, it's simply that indeed I have specify a multifunction path "0000:02".
> 
> I think it should better/safe to die here, instead to simply warn and
> continue.
i agree die'ing here is better, for the mapped case we could do that now,
but for the old case of a pciid we can't (for backwards compat) until 8.0

[snip]

>>
>> maybe not related, but after that, stop/start are not working anymore
>>
>> root@pve2:~# qm stop 101
>> PCI device mapping invalid (hardware probably changed): 'mdev'
>> configured but should not be
>>
>> root@pve2:~# qm start 101
>> PCI device mapping invalid (hardware probably changed): 'mdev'
>> configured but should not be
>>

i had this also happen here once, when we do 'normal' pci passthrough
we reset the devices (via sysfs) and it seems the nvidia driver/card
does not like that and does not enable the mediated devices until
a reboot ....

the code then sees a hardware/feature mismatch and refuses to start.
this is done to prevent a start with passthrough on hardware change,
i.e. if someone adds/removes a device and suddenly
the device at path X is not the same anymore)