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Date:   Tue, 27 Mar 2018 13:19:16 +0200
From:   Cornelia Huck <cohuck@redhat.com>
To:     Pierre Morel <pmorel@linux.vnet.ibm.com>
Cc:     Tony Krowiak <akrowiak@linux.vnet.ibm.com>,
        linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org, freude@de.ibm.com, schwidefsky@de.ibm.com,
        heiko.carstens@de.ibm.com, borntraeger@de.ibm.com,
        kwankhede@nvidia.com, bjsdjshi@linux.vnet.ibm.com,
        pbonzini@redhat.com, alex.williamson@redhat.com,
        alifm@linux.vnet.ibm.com, mjrosato@linux.vnet.ibm.com,
        jjherne@linux.vnet.ibm.com, thuth@redhat.com,
        pasic@linux.vnet.ibm.com, berrange@redhat.com,
        fiuczy@linux.vnet.ibm.com, buendgen@de.ibm.com
Subject: Re: [PATCH v3 11/14] s390: vfio-ap: sysfs interface to view matrix
 mdev matrix
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On Thu, 15 Mar 2018 10:42:33 +0100
Pierre Morel <pmorel@linux.vnet.ibm.com> wrote:

> On 14/03/2018 19:25, 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:
> >
> > 	cat matrix
> >
> > Signed-off-by: Tony Krowiak <akrowiak@linux.vnet.ibm.com>
> > ---
> >   drivers/s390/crypto/vfio_ap_ops.c |   39 +++++++++++++++++++++++++++++++++++++
> >   1 files changed, 39 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> > index 461d450..04f7a92 100644
> > --- a/drivers/s390/crypto/vfio_ap_ops.c
> > +++ b/drivers/s390/crypto/vfio_ap_ops.c
> > @@ -692,6 +692,44 @@ static ssize_t control_domains_show(struct device *dev,
> >   }
> >   DEVICE_ATTR_RO(control_domains);
> >
> > +static ssize_t matrix_show(struct device *dev, struct device_attribute *attr,
> > +			   char *buf)
> > +{
> > +	struct mdev_device *mdev = mdev_from_dev(dev);
> > +	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
> > +	char *bufpos = buf;
> > +	unsigned long apid;
> > +	unsigned long apqi;
> > +	int nchars = 0;
> > +	int n;
> > +
> > +	n = sprintf(bufpos, "ADAPTER.DOMAIN\n");  
> 
> For easy parsing it is better to only report the interesting data
> and let a user space utility make fancy presentation.

+1. Attributes should normally be simple, one-value things.

> 
> > +	bufpos += n;
> > +	nchars += n;
> > +
> > +	n = sprintf(bufpos, "--------------\n");
> > +	bufpos += n;
> > +	nchars += n;
> > +
> > +	for_each_set_bit_inv(apid, matrix_mdev->matrix->apm,
> > +			     matrix_mdev->matrix->apm_max) {
> > +		n = sprintf(bufpos, "%02lx\n", apid);
> > +		bufpos += n;
> > +		nchars += n;
> > +
> > +		for_each_set_bit_inv(apqi, matrix_mdev->matrix->aqm,
> > +				     matrix_mdev->matrix->aqm_max) {
> > +			n = sprintf(bufpos, "%02lx.%04lx\n", apid, apqi);
> > +			bufpos += n;
> > +			nchars += n;
> > +		}
> > +	}
> > +
> > +	return nchars;
> > +}
> > +DEVICE_ATTR_RO(matrix);
> > +
> > +
> >   static struct attribute *vfio_ap_mdev_attrs[] = {
> >   	&dev_attr_assign_adapter.attr,
> >   	&dev_attr_unassign_adapter.attr,
> > @@ -700,6 +738,7 @@ static ssize_t control_domains_show(struct device *dev,
> >   	&dev_attr_assign_control_domain.attr,
> >   	&dev_attr_unassign_control_domain.attr,
> >   	&dev_attr_control_domains.attr,
> > +	&dev_attr_matrix.attr,
> >   	NULL,
> >   };
> >  
>