Re: [RFC PATCH v1] fixup! s390/vfio-ap: Notify userspace that guest's AP config changed when mdev removed

[Rorie Reyes <rreyes@linux.ibm.com>]

On 3/4/25 9:27 AM, Anthony Krowiak wrote:
>
>
>
> On 3/4/25 9:18 AM, Rorie Reyes wrote:
>>
>>
>> On 3/4/25 8:36 AM, Anthony Krowiak wrote:
>>>>     static void vfio_ap_mdev_update_guest_apcb(struct 
>>>> ap_matrix_mdev *matrix_mdev)
>>>> @@ -1870,7 +1870,6 @@ static void vfio_ap_mdev_unset_kvm(struct 
>>>> ap_matrix_mdev *matrix_mdev)
>>>>           get_update_locks_for_kvm(kvm);
>>>>             kvm_arch_crypto_clear_masks(kvm);
>>>> -        signal_guest_ap_cfg_changed(matrix_mdev);
>>>>           vfio_ap_mdev_reset_queues(matrix_mdev);
>>>>           kvm_put_kvm(kvm);
>>>>           matrix_mdev->kvm = NULL;
>>>> @@ -2057,6 +2056,14 @@ static void vfio_ap_mdev_request(struct 
>>>> vfio_device *vdev, unsigned int count)
>>>>         matrix_mdev = container_of(vdev, struct ap_matrix_mdev, vdev);
>>>>   +    if (matrix_mdev->kvm) {
>>>> +        get_update_locks_for_kvm(matrix_mdev->kvm);
>>>
>>> I know we talked about this prior to submission of this patch, but 
>>> looking at this again I think
>>> you should use the get_update_locks_for_mdev() function for two 
>>> reasons:
>>>
>>> 1. It is safer because it will take the matrix_dev->guests_lock 
>>> which will prevent the matrix_mdev->kvm
>>>     field from changing before you check it
>>>
>> So I'll replace *get_update_locks_for_kvm(matrix_mdev->kvm)* with 
>> *get_update_locks_for_mdev(&matrix_dev->guests_lock)*
>
> See code below:get_update_locks_for_mdev(matrix_mdev)
> That function will take the guests_lock
>
Ah ok, I see now. I'll make those changes. Thank you!
>>> 2. I will eliminate the need for the else
>>>
>>> get_update_locks_for_mdev(matrix_mdev)
>>> if (matrix_mdev->kvm) {
>>>     clear the masks
>>>     signal guest config changed
>>> }
>>> ...
>>> release_update_locks_for_mdev(matrix_mdev); Sorry about not seeing 
>>> this before you posted this patch.
>>>> + kvm_arch_crypto_clear_masks(matrix_mdev->kvm);
>>>> +        signal_guest_ap_cfg_changed(matrix_mdev);
>>>> +    } else {
>>>> +        mutex_lock(&matrix_dev->mdevs_lock);
>>>> +    }
>> So remove the else statement that contains the mutex function
>