Re: [PATCH v4 3/5] vfio/pci: Disable INTx in vfio_realize error path

[Joao Martins <joao.m.martins@oracle.com>]

On 29/06/2023 16:13, Cédric Le Goater wrote:
> On 6/29/23 13:24, Joao Martins wrote:
>> On 29/06/2023 09:40, Zhenzhong Duan wrote:
>>> When vfio realize fails, INTx isn't disabled if it has been enabled.
>>> This may confuse host side with unhandled interrupt report.
>>>
>>> Add a new label to be used for vfio_intx_enable() failed case.
>>>
>>> Fixes: a9994687cb9b ("vfio/display: core & wireup")
>>> Fixes: b290659fc3dd ("hw/vfio/display: add ramfb support")
>>> Fixes: c62a0c7ce34e ("vfio/display: add xres + yres properties")
>>
>> Sounds to me the correct Fixes tag is the same as first patch i.e.:
>>
>> Fixes: c5478fea27ac ("vfio/pci: Respond to KVM irqchip change notifier")
>>
>>> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
>>
>> Looks good, but see some clarifications below.
>>
>>> ---
>>>   hw/vfio/pci.c | 4 +++-
>>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
>>> index ab6645ba60af..54a8179d1c64 100644
>>> --- a/hw/vfio/pci.c
>>> +++ b/hw/vfio/pci.c
>>> @@ -3167,7 +3167,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
>>>           kvm_irqchip_add_change_notifier(&vdev->irqchip_change_notifier);
>>>           ret = vfio_intx_enable(vdev, errp);
>>>           if (ret) {
>>> -            goto out_deregister;
>>> +            goto out_intx_disable;
>>>           }
>>>       }
>>>   @@ -3220,6 +3220,8 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
>>>       return;
>>>     out_deregister:
>>> +    vfio_disable_interrupts(vdev);
>>
>> You are calling vfio_disable_interrupts() when what you want is
>> vfio_intx_disable() ? But I guess your thinking was to call
>> vfio_disable_interrupt() which eventually calls vfio_intx_disable() in case INTx
>> was really setup, thus saving the duplicated check. The MSIx/MSI in realize() I
>> don't think they will be enabled at this point. Let me know if I misunderstood.
>>
>>> +out_intx_disable:
>>
>> Maybe 'out_intx_teardown' or 'out_intx_deregister' because you are not really
>> disabling INTx.
> 
> or simply extract from vfio_disable_interrupts() :
>  
>     if (vdev->interrupt == VFIO_INT_INTx) {
>         vfio_intx_disable(vdev);
>     }
> 
> and add the above code before cleaning up the intx routing
> notifier without any new goto labels.
> 
An even better option indeed.