Re: [PATCH v2 5/7] s390: vfio-ap: allow hot plug/unplug of AP resources using mdev device

[Tony Krowiak <akrowiak@linux.ibm.com>]

On 5/6/19 6:42 AM, Pierre Morel wrote:
> On 03/05/2019 23:14, Tony Krowiak wrote:
>> Let's allow AP resources to be assigned to or unassigned from an AP 
>> matrix
>> mdev device while it is in use by a guest. If a guest is using the mdev
>> device while assignment is taking place, the guest will be granted access
>> to the resource as long as the guest will not be given access to an AP
>> queue device that is not bound to the vfio_ap device driver. If a 
>> guest is
>> using the mdev device while unassignment is taking place, access to the
>> resource will be taken from the guest.
>>
>> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
>> ---
>>   drivers/s390/crypto/vfio_ap_ops.c | 116 
>> ++++++++++++++++++++++++++++----------
>>   1 file changed, 86 insertions(+), 30 deletions(-)
>>
>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c 
>> b/drivers/s390/crypto/vfio_ap_ops.c
>> index ea24caf17a16..ede45184eb67 100644
>> --- a/drivers/s390/crypto/vfio_ap_ops.c
>> +++ b/drivers/s390/crypto/vfio_ap_ops.c
>> @@ -226,6 +226,8 @@ static struct device 
>> *vfio_ap_get_queue_dev(unsigned long apid,
>>                     &apqn, match_apqn);
>>   }
>> +
>> +
> 
> two white lines

I will fix it.

> 
>>   static int vfio_ap_mdev_validate_masks(unsigned long *apm, unsigned 
>> long *aqm)
>>   {
>>       int ret;
>> @@ -237,6 +239,26 @@ static int vfio_ap_mdev_validate_masks(unsigned 
>> long *apm, unsigned long *aqm)
>>       return vfio_ap_mdev_verify_no_sharing(apm, aqm);
>>   }
>> +static bool vfio_ap_queues_on_drv(unsigned long *apm, unsigned long 
>> *aqm)
>> +{
>> +    unsigned long apid, apqi, apqn;
>> +    struct device *dev;
>> +
>> +    for_each_set_bit_inv(apid, apm, AP_DEVICES) {
>> +        for_each_set_bit_inv(apqi, aqm, AP_DOMAINS) {
>> +            apqn = AP_MKQID(apid, apqi);
> 
> You do not use apqn in the function.

Must be a remnant of another iteration. I'll remove it.

> 
>> +
>> +            dev = vfio_ap_get_queue_dev(apid, apqi);
>> +            if (!dev)
>> +                return false;
>> +
>> +            put_device(dev);
>> +        }
>> +    }
>> +
>> +    return true;
>> +}
>> +
>>   /**
>>    * assign_adapter_store
>>    *
>> @@ -247,7 +269,10 @@ static int vfio_ap_mdev_validate_masks(unsigned 
>> long *apm, unsigned long *aqm)
>>    * @count:    the number of bytes in @buf
>>    *
>>    * Parses the APID from @buf and sets the corresponding bit in the 
>> mediated
>> - * matrix device's APM.
>> + * matrix device's APM. If a guest is using the mediated matrix 
>> device and each
>> + * new APQN formed as a result of the assignment identifies an AP 
>> queue device
>> + * that is bound to the vfio_ap device driver, the guest will be 
>> granted access
>> + * to the adapter with the specified APID.
>>    *
>>    * Returns the number of bytes processed if the APID is valid; 
>> otherwise,
>>    * returns one of the following errors:
>> @@ -279,10 +304,6 @@ static ssize_t assign_adapter_store(struct device 
>> *dev,
>>       struct mdev_device *mdev = mdev_from_dev(dev);
>>       struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
>> -    /* If the guest is running, disallow assignment of adapter */
>> -    if (matrix_mdev->kvm)
>> -        return -EBUSY;
>> -
>>       ret = kstrtoul(buf, 0, &apid);
>>       if (ret)
>>           return ret;
>> @@ -300,6 +321,14 @@ static ssize_t assign_adapter_store(struct device 
>> *dev,
>>           return ret;
>>       }
>>       set_bit_inv(apid, matrix_mdev->matrix.apm);
>> +
>> +    if (matrix_mdev->shadow_crycb) {
>> +        if (vfio_ap_queues_on_drv(apm,
>> +                      matrix_mdev->shadow_crycb->aqm)) {
>> +            set_bit_inv(apid, matrix_mdev->shadow_crycb->apm);
>> +            vfio_ap_mdev_update_crycb(matrix_mdev);
>> +        }
>> +    }
>>       mutex_unlock(&matrix_dev->lock);
>>       return count;
>> @@ -315,7 +344,9 @@ static DEVICE_ATTR_WO(assign_adapter);
>>    * @count:    the number of bytes in @buf
>>    *
>>    * Parses the APID from @buf and clears the corresponding bit in the 
>> mediated
>> - * matrix device's APM.
>> + * matrix device's APM. If a guest is using the mediated matrix 
>> device and has
>> + * access to the AP adapter with the specified APID, access to the 
>> adapter will
>> + * be taken from the guest.
>>    *
>>    * Returns the number of bytes processed if the APID is valid; 
>> otherwise,
>>    * returns one of the following errors:
>> @@ -332,10 +363,6 @@ static ssize_t unassign_adapter_store(struct 
>> device *dev,
>>       struct mdev_device *mdev = mdev_from_dev(dev);
>>       struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
>> -    /* If the guest is running, disallow un-assignment of adapter */
>> -    if (matrix_mdev->kvm)
>> -        return -EBUSY;
>> -
>>       ret = kstrtoul(buf, 0, &apid);
>>       if (ret)
>>           return ret;
>> @@ -345,6 +372,13 @@ static ssize_t unassign_adapter_store(struct 
>> device *dev,
>>       mutex_lock(&matrix_dev->lock);
>>       clear_bit_inv((unsigned long)apid, matrix_mdev->matrix.apm);
>> +
>> +    if (matrix_mdev->shadow_crycb) {
>> +        if (test_bit_inv(apid, matrix_mdev->shadow_crycb->apm)) {
>> +            clear_bit_inv(apid, matrix_mdev->shadow_crycb->apm);
>> +            vfio_ap_mdev_update_crycb(matrix_mdev);
>> +        }
>> +    }
>>       mutex_unlock(&matrix_dev->lock);
>>       return count;
>> @@ -361,7 +395,10 @@ static DEVICE_ATTR_WO(unassign_adapter);
>>    * @count:    the number of bytes in @buf
>>    *
>>    * Parses the APQI from @buf and sets the corresponding bit in the 
>> mediated
>> - * matrix device's AQM.
>> + * matrix device's AQM. If a guest is using the mediated matrix 
>> device and each
>> + * new APQN formed as a result of the assignment identifies an AP 
>> queue device
>> + * that is bound to the vfio_ap device driver, the guest will be 
>> given access
>> + * to the AP queue(s) with the specified APQI.
>>    *
>>    * Returns the number of bytes processed if the APQI is valid; 
>> otherwise returns
>>    * one of the following errors:
>> @@ -394,10 +431,6 @@ static ssize_t assign_domain_store(struct device 
>> *dev,
>>       struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
>>       unsigned long max_apqi = matrix_mdev->matrix.aqm_max;
>> -    /* If the guest is running, disallow assignment of domain */
>> -    if (matrix_mdev->kvm)
>> -        return -EBUSY;
>> -
>>       ret = kstrtoul(buf, 0, &apqi);
>>       if (ret)
>>           return ret;
>> @@ -414,6 +447,14 @@ static ssize_t assign_domain_store(struct device 
>> *dev,
>>           return ret;
>>       }
>>       set_bit_inv(apqi, matrix_mdev->matrix.aqm);
>> +
>> +    if (matrix_mdev->shadow_crycb) {
>> +        if (vfio_ap_queues_on_drv(matrix_mdev->shadow_crycb->apm,
>> +                      aqm)) {
>> +            set_bit_inv(apqi, matrix_mdev->shadow_crycb->aqm);
>> +            vfio_ap_mdev_update_crycb(matrix_mdev);
>> +        }
>> +    }
>>       mutex_unlock(&matrix_dev->lock);
>>       return count;
>> @@ -431,7 +472,9 @@ static DEVICE_ATTR_WO(assign_domain);
>>    * @count:    the number of bytes in @buf
>>    *
>>    * Parses the APQI from @buf and clears the corresponding bit in the
>> - * mediated matrix device's AQM.
>> + * mediated matrix device's AQM. If a guest is using the mediated 
>> matrix device
>> + * and has access to queue(s) with the specified domain APQI, access to
>> + * the queue(s) will be taken away from the guest.
>>    *
>>    * Returns the number of bytes processed if the APQI is valid; 
>> otherwise,
>>    * returns one of the following errors:
>> @@ -447,10 +490,6 @@ static ssize_t unassign_domain_store(struct 
>> device *dev,
>>       struct mdev_device *mdev = mdev_from_dev(dev);
>>       struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
>> -    /* If the guest is running, disallow un-assignment of domain */
>> -    if (matrix_mdev->kvm)
>> -        return -EBUSY;
>> -
>>       ret = kstrtoul(buf, 0, &apqi);
>>       if (ret)
>>           return ret;
>> @@ -460,6 +499,13 @@ static ssize_t unassign_domain_store(struct 
>> device *dev,
>>       mutex_lock(&matrix_dev->lock);
>>       clear_bit_inv((unsigned long)apqi, matrix_mdev->matrix.aqm);
>> +
>> +    if (matrix_mdev->shadow_crycb) {
>> +        if (test_bit_inv(apqi, matrix_mdev->shadow_crycb->aqm)) {
>> +            clear_bit_inv(apqi, matrix_mdev->shadow_crycb->aqm);
>> +            vfio_ap_mdev_update_crycb(matrix_mdev);
>> +        }
>> +    }
>>       mutex_unlock(&matrix_dev->lock);
>>       return count;
>> @@ -475,7 +521,9 @@ static DEVICE_ATTR_WO(unassign_domain);
>>    * @count:    the number of bytes in @buf
>>    *
>>    * Parses the domain ID from @buf and sets the corresponding bit in 
>> the mediated
>> - * matrix device's ADM.
>> + * matrix device's ADM. If a guest is using the mediated matrix 
>> device and the
>> + * guest does not have access to the control domain with the 
>> specified ID, the
>> + * guest will be granted access to it.
>>    *
>>    * Returns the number of bytes processed if the domain ID is valid; 
>> otherwise,
>>    * returns one of the following errors:
>> @@ -491,10 +539,6 @@ static ssize_t assign_control_domain_store(struct 
>> device *dev,
>>       struct mdev_device *mdev = mdev_from_dev(dev);
>>       struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
>> -    /* If the guest is running, disallow assignment of control domain */
>> -    if (matrix_mdev->kvm)
>> -        return -EBUSY;
>> -
>>       ret = kstrtoul(buf, 0, &id);
>>       if (ret)
>>           return ret;
>> @@ -504,6 +548,13 @@ static ssize_t assign_control_domain_store(struct 
>> device *dev,
>>       mutex_lock(&matrix_dev->lock);
>>       set_bit_inv(id, matrix_mdev->matrix.adm);
>> +
>> +    if (matrix_mdev->shadow_crycb) {
>> +        if (!test_bit_inv(id, matrix_mdev->shadow_crycb->adm)) {
>> +            set_bit_inv(id, matrix_mdev->shadow_crycb->adm);
>> +            vfio_ap_mdev_update_crycb(matrix_mdev);
>> +        }
>> +    }
>>       mutex_unlock(&matrix_dev->lock);
>>       return count;
>> @@ -519,7 +570,9 @@ static DEVICE_ATTR_WO(assign_control_domain);
>>    * @count:    the number of bytes in @buf
>>    *
>>    * Parses the domain ID from @buf and clears the corresponding bit 
>> in the
>> - * mediated matrix device's ADM.
>> + * mediated matrix device's ADM. If a guest is using the mediated 
>> matrix device
>> + * and has access to control domain with the specified domain ID, 
>> access to
>> + * the control domain will be taken from the guest.
>>    *
>>    * Returns the number of bytes processed if the domain ID is valid; 
>> otherwise,
>>    * returns one of the following errors:
>> @@ -536,10 +589,6 @@ static ssize_t 
>> unassign_control_domain_store(struct device *dev,
>>       struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
>>       unsigned long max_domid =  matrix_mdev->matrix.adm_max;
>> -    /* If the guest is running, disallow un-assignment of control 
>> domain */
>> -    if (matrix_mdev->kvm)
>> -        return -EBUSY;
>> -
>>       ret = kstrtoul(buf, 0, &domid);
>>       if (ret)
>>           return ret;
>> @@ -548,6 +597,13 @@ static ssize_t 
>> unassign_control_domain_store(struct device *dev,
>>       mutex_lock(&matrix_dev->lock);
>>       clear_bit_inv(domid, matrix_mdev->matrix.adm);
>> +
>> +    if (matrix_mdev->shadow_crycb) {
>> +        if (test_bit_inv(domid, matrix_mdev->shadow_crycb->adm)) {
>> +            clear_bit_inv(domid, matrix_mdev->shadow_crycb->adm);
>> +            vfio_ap_mdev_update_crycb(matrix_mdev);
>> +        }
>> +    }
>>       mutex_unlock(&matrix_dev->lock);
>>       return count;
>>
> 
> beside the two NITs, look good to me.
> Still need to test.
> 
> 
>