linux-kernel - Re: [PATCH v18 13/18] s390/vfio-ap: implement in-use callback for vfio

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Date:   Tue, 22 Mar 2022 09:30:58 -0400
From:   Tony Krowiak <akrowiak@...ux.ibm.com>
To:     jjherne@...ux.ibm.com, linux-s390@...r.kernel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     freude@...ux.ibm.com, borntraeger@...ibm.com, cohuck@...hat.com,
        mjrosato@...ux.ibm.com, pasic@...ux.ibm.com,
        alex.williamson@...hat.com, kwankhede@...dia.com,
        fiuczy@...ux.ibm.com
Subject: Re: [PATCH v18 13/18] s390/vfio-ap: implement in-use callback for
 vfio_ap driver



On 3/22/22 09:13, Jason J. Herne wrote:
> On 2/14/22 19:50, Tony Krowiak wrote:
> ...
>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c 
>> b/drivers/s390/crypto/vfio_ap_ops.c
>> index e9f7ec6fc6a5..63dfb9b89581 100644
>> --- a/drivers/s390/crypto/vfio_ap_ops.c
>> +++ b/drivers/s390/crypto/vfio_ap_ops.c
>> @@ -617,10 +617,32 @@ static int 
>> vfio_ap_mdev_verify_no_sharing(unsigned long *mdev_apm,
>>       return 0;
>>   }
>>   +/**
>> + * vfio_ap_mdev_validate_masks - verify that the APQNs assigned to 
>> the mdev are
>> + *                 not reserved for the default zcrypt driver and
>> + *                 are not assigned to another mdev.
>> + *
>> + * @matrix_mdev: the mdev to which the APQNs being validated are 
>> assigned.
>> + *
>> + * Return: One of the following values:
>> + * o the error returned from the 
>> ap_apqn_in_matrix_owned_by_def_drv() function,
>> + *   most likely -EBUSY indicating the ap_perms_mutex lock is 
>> already held.
>> + * o EADDRNOTAVAIL if an APQN assigned to @matrix_mdev is reserved 
>> for the
>> + *           zcrypt default driver.
>> + * o EADDRINUSE if an APQN assigned to @matrix_mdev is assigned to 
>> another mdev
>> + * o A zero indicating validation succeeded.
>> + */
>>   static int vfio_ap_mdev_validate_masks(struct ap_matrix_mdev 
>> *matrix_mdev)
>>   {
>> -    if (ap_apqn_in_matrix_owned_by_def_drv(matrix_mdev->matrix.apm,
>> -                           matrix_mdev->matrix.aqm))
>> +    int ret;
>> +
>> +    ret = ap_apqn_in_matrix_owned_by_def_drv(matrix_mdev->matrix.apm,
>> +                         matrix_mdev->matrix.aqm);
>> +
>> +    if (ret < 0)
>> +        return ret;
>> +
>> +    if (ret == 1)
>>           return -EADDRNOTAVAIL;
>
> I took a look at ap_apqn_in_matrix_owned_by_def_drv(). It appears that 
> this function
> can only ever return 0 or 1. This patch is changed to watch for a 
> negative return
> value from ap_apqn_in_matrix_owned_by_def_drv(). Am I missing something?

That's odd, careless error, I'll fix it.

>
>