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

[Tony Krowiak <akrowiak@xxxxxxxxxxxxx>]

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@xxxxxxxxxxxxx>
> > ---
> >   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.