Re: [PATCH v26 03/17] vfio: Add save and load functions for VFIO PCI devices

[Zenghui Yu <yuzenghui@huawei.com>]

On 2020/9/25 6:49, Alex Williamson wrote:
>> +    } else if (interrupt_type == VFIO_INT_MSIX) {
>> +        uint16_t offset;
>> +
>> +        msix_load(pdev, f);
>> +        offset = pci_default_read_config(pdev,
>> +                                       pdev->msix_cap + PCI_MSIX_FLAGS + 1, 2);
>> +        /* load enable bit and maskall bit */
>> +        vfio_pci_write_config(pdev, pdev->msix_cap + PCI_MSIX_FLAGS + 1,
>> +                              offset, 2);

It isn't clear that what purpose this load operation serves.  The config
space has already been restored and we'll see that MSI-X _was_ and _is_
enabled (or disabled).  vfio_msix_enable() will therefore not be invoked
and no vectors would actually be enabled...  Not sure if I had missed
something.

>> +    }
>> +    return 0;
> 
> It seems this could be simplified down to:
> 
> if (msi_enabled(pdev)) {
>      vfio_msi_enable(vdev);
> } else if (msix_enabled(pdev)) {
>      msix_load(pdev, f);
>      vfio_msix_enable(vdev);
> }

And it seems that this has fixed something :-)


Thanks,
Zenghui