linux-kernel - Re: [PATCH v13 08/15] s390/vfio-ap: sysfs attribute to display the guest's matrix

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Date:   Mon, 11 Jan 2021 23:58:06 +0100
From:   Halil Pasic <pasic@...ux.ibm.com>
To:     Tony Krowiak <akrowiak@...ux.ibm.com>
Cc:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, freude@...ux.ibm.com, borntraeger@...ibm.com,
        cohuck@...hat.com, mjrosato@...ux.ibm.com,
        alex.williamson@...hat.com, kwankhede@...dia.com,
        fiuczy@...ux.ibm.com, frankja@...ux.ibm.com, david@...hat.com,
        hca@...ux.ibm.com, gor@...ux.ibm.com
Subject: Re: [PATCH v13 08/15] s390/vfio-ap: sysfs attribute to display the
 guest's matrix

On Tue, 22 Dec 2020 20:15:59 -0500
Tony Krowiak <akrowiak@...ux.ibm.com> wrote:

> The matrix of adapters and domains configured in a guest's APCB may
> differ from the matrix of adapters and domains assigned to the matrix mdev,
> so this patch introduces a sysfs attribute to display the matrix of
> adapters and domains that are or will be assigned to the APCB of a guest
> that is or will be using the matrix mdev. For a matrix mdev denoted by
> $uuid, the guest matrix can be displayed as follows:
> 
>    cat /sys/devices/vfio_ap/matrix/$uuid/guest_matrix
> 
> Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>

Reviewed-by: Halil Pasic <pasic@...ux.ibm.com>

But because vfio_ap_mdev_commit_shadow_apcb() is not used (see prev
patch) the attribute won't show the guest matrix at this point. :(

> ---
>  drivers/s390/crypto/vfio_ap_ops.c | 51 ++++++++++++++++++++++---------
>  1 file changed, 37 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index 44b3a81cadfb..1b1d5975ee0e 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -894,29 +894,24 @@ static ssize_t control_domains_show(struct device *dev,
>  }
>  static DEVICE_ATTR_RO(control_domains);
>  
> -static ssize_t matrix_show(struct device *dev, struct device_attribute *attr,
> -			   char *buf)
> +static ssize_t vfio_ap_mdev_matrix_show(struct ap_matrix *matrix, 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;
>  	unsigned long apid1;
>  	unsigned long apqi1;
> -	unsigned long napm_bits = matrix_mdev->matrix.apm_max + 1;
> -	unsigned long naqm_bits = matrix_mdev->matrix.aqm_max + 1;
> +	unsigned long napm_bits = matrix->apm_max + 1;
> +	unsigned long naqm_bits = matrix->aqm_max + 1;
>  	int nchars = 0;
>  	int n;
>  
> -	apid1 = find_first_bit_inv(matrix_mdev->matrix.apm, napm_bits);
> -	apqi1 = find_first_bit_inv(matrix_mdev->matrix.aqm, naqm_bits);
> -
> -	mutex_lock(&matrix_dev->lock);
> +	apid1 = find_first_bit_inv(matrix->apm, napm_bits);
> +	apqi1 = find_first_bit_inv(matrix->aqm, naqm_bits);
>  
>  	if ((apid1 < napm_bits) && (apqi1 < naqm_bits)) {
> -		for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, napm_bits) {
> -			for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm,
> +		for_each_set_bit_inv(apid, matrix->apm, napm_bits) {
> +			for_each_set_bit_inv(apqi, matrix->aqm,
>  					     naqm_bits) {
>  				n = sprintf(bufpos, "%02lx.%04lx\n", apid,
>  					    apqi);
> @@ -925,25 +920,52 @@ static ssize_t matrix_show(struct device *dev, struct device_attribute *attr,
>  			}
>  		}
>  	} else if (apid1 < napm_bits) {
> -		for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, napm_bits) {
> +		for_each_set_bit_inv(apid, matrix->apm, napm_bits) {
>  			n = sprintf(bufpos, "%02lx.\n", apid);
>  			bufpos += n;
>  			nchars += n;
>  		}
>  	} else if (apqi1 < naqm_bits) {
> -		for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, naqm_bits) {
> +		for_each_set_bit_inv(apqi, matrix->aqm, naqm_bits) {
>  			n = sprintf(bufpos, ".%04lx\n", apqi);
>  			bufpos += n;
>  			nchars += n;
>  		}
>  	}
>  
> +	return nchars;
> +}
> +
> +static ssize_t matrix_show(struct device *dev, struct device_attribute *attr,
> +			   char *buf)
> +{
> +	ssize_t nchars;
> +	struct mdev_device *mdev = mdev_from_dev(dev);
> +	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
> +
> +	mutex_lock(&matrix_dev->lock);
> +	nchars = vfio_ap_mdev_matrix_show(&matrix_mdev->matrix, buf);
>  	mutex_unlock(&matrix_dev->lock);
>  
>  	return nchars;
>  }
>  static DEVICE_ATTR_RO(matrix);
>  
> +static ssize_t guest_matrix_show(struct device *dev,
> +				 struct device_attribute *attr, char *buf)
> +{
> +	ssize_t nchars;
> +	struct mdev_device *mdev = mdev_from_dev(dev);
> +	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
> +
> +	mutex_lock(&matrix_dev->lock);
> +	nchars = vfio_ap_mdev_matrix_show(&matrix_mdev->shadow_apcb, buf);
> +	mutex_unlock(&matrix_dev->lock);
> +
> +	return nchars;
> +}
> +static DEVICE_ATTR_RO(guest_matrix);
> +
>  static struct attribute *vfio_ap_mdev_attrs[] = {
>  	&dev_attr_assign_adapter.attr,
>  	&dev_attr_unassign_adapter.attr,
> @@ -953,6 +975,7 @@ static struct attribute *vfio_ap_mdev_attrs[] = {
>  	&dev_attr_unassign_control_domain.attr,
>  	&dev_attr_control_domains.attr,
>  	&dev_attr_matrix.attr,
> +	&dev_attr_guest_matrix.attr,
>  	NULL,
>  };
>