Re: [PATCH v5 10/13] s390: vfio-ap: sysfs interface to view matrix mdev matrix

[Pierre Morel]

On 23/05/2018 16:38, Tony Krowiak wrote:
> On 05/16/2018 03:55 AM, Pierre Morel wrote:
> > On 07/05/2018 17:11, Tony Krowiak wrote:
> > > Provides a sysfs interface to view the AP matrix configured for the
> > > mediated matrix device.
> > >
> > > The relevant sysfs structures are:
> > >
> > > /sys/devices/vfio_ap
> > > ... [matrix]
> > > ...... [mdev_supported_types]
> > > ......... [vfio_ap-passthrough]
> > > ............ [devices]
> > > ...............[$uuid]
> > > .................. matrix
> > >
> > > To view the matrix configured for the mediated matrix device,
> > > print the matrix file:
> >
> > This is the configured matrix, not the one used by the guest.
> > Nothing in the patches protect against binding a queue and assigning
> > a new AP when the guest runs.
> > The card and queue will be showed by this entry.
>
> Of course, as stated above, this is the matrix configured for the
> mediated matrix device. Are you suggesting here that the driver
> should prevent assigning a new adapter or domain while a guest is
> running? Couldn't this be a step in the process for hot (un)plugging
> AP queues?

No, I mean what is the point to show this?
It is not what the guest sees.
Has it any use case?

> > > ÂÂÂ cat matrix
> > >
> > > Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxxxxxxx>
> > > ---
> > > Â drivers/s390/crypto/vfio_ap_ops.c |ÂÂ 31 
> > > +++++++++++++++++++++++++++++++
> > > Â 1 files changed, 31 insertions(+), 0 deletions(-)
> > >
> > > diff --git a/drivers/s390/crypto/vfio_ap_ops.c 
> > > b/drivers/s390/crypto/vfio_ap_ops.c
> > > index 755be1d..81e03b8 100644
> > > --- a/drivers/s390/crypto/vfio_ap_ops.c
> > > +++ b/drivers/s390/crypto/vfio_ap_ops.c
> > > @@ -716,6 +716,36 @@ static ssize_t control_domains_show(struct 
> > > device *dev,
> > > Â }
> > > Â DEVICE_ATTR_RO(control_domains);
> > >
> > > +static ssize_t matrix_show(struct device *dev, struct 
> > > device_attribute *attr,
> > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂ char *buf)
> > > +{
> > > +ÂÂÂ struct mdev_device *mdev = mdev_from_dev(dev);
> > > +ÂÂÂ struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
> > > +ÂÂÂ char *bufpos = buf;
> > > +ÂÂÂ unsigned long apid;
> > > +ÂÂÂ unsigned long apqi;
> > > +ÂÂÂ unsigned long napm = matrix_mdev->matrix.apm_max + 1;
> > > +ÂÂÂ unsigned long naqm = matrix_mdev->matrix.aqm_max + 1;
> > > +ÂÂÂ int nchars = 0;
> > > +ÂÂÂ int n;
> > > +
> > > +ÂÂÂ for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, napm) {
> > > +ÂÂÂÂÂÂÂ n = sprintf(bufpos, "%02lx\n", apid);
> > > +ÂÂÂÂÂÂÂ bufpos += n;
> > > +ÂÂÂÂÂÂÂ nchars += n;
> > > +
> > > +ÂÂÂÂÂÂÂ for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, naqm) {
> > > +ÂÂÂÂÂÂÂÂÂÂÂ n = sprintf(bufpos, "%02lx.%04lx\n", apid, apqi);
> > > +ÂÂÂÂÂÂÂÂÂÂÂ bufpos += n;
> > > +ÂÂÂÂÂÂÂÂÂÂÂ nchars += n;
> > > +ÂÂÂÂÂÂÂ }
> > > +ÂÂÂ }
> > > +
> > > +ÂÂÂ return nchars;
> > > +}
> > > +DEVICE_ATTR_RO(matrix);
> > > +
> > > +
> > > Â static struct attribute *vfio_ap_mdev_attrs[] = {
> > > ÂÂÂÂÂ &dev_attr_assign_adapter.attr,
> > > ÂÂÂÂÂ &dev_attr_unassign_adapter.attr,
> > > @@ -724,6 +754,7 @@ static ssize_t control_domains_show(struct 
> > > device *dev,
> > > ÂÂÂÂÂ &dev_attr_assign_control_domain.attr,
> > > ÂÂÂÂÂ &dev_attr_unassign_control_domain.attr,
> > > ÂÂÂÂÂ &dev_attr_control_domains.attr,
> > > +ÂÂÂ &dev_attr_matrix.attr,
> > > ÂÂÂÂÂ NULL,
> > > Â };

--
Pierre Morel
Linux/KVM/QEMU in BÃblingen - Germany