Re: [PATCH v10 07/16] s390/vfio-ap: sysfs attribute to display the guest's matrix

Cornelia Huck
2020-09-17T14:34:48Z

On Fri, 21 Aug 2020 15:56:07 -0400
Tony Krowiak <akrowiak@linux.ibm.com> wrote:

> The matrix of adapters and domains configured in a guest's CRYCB 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 a guest
> using the matrix mdev. For a matrix mdev denoted by $uuid, the crycb for a
> guest using the matrix mdev can be displayed as follows:
>
> cat /sys/devices/vfio_ap/matrix/$uuid/guest_matrix
>
> If a guest is not using the matrix mdev at the time the crycb is displayed,
> an error (ENODEV) will be returned.
>
> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
> ---
> drivers/s390/crypto/vfio_ap_ops.c | 58 +++++++++++++++++++++++++++++++
> 1 file changed, 58 insertions(+)
>
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index efb229033f9e..30bf23734af6 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -1119,6 +1119,63 @@ static ssize_t matrix_show(struct device *dev, struct device_attribute *attr,
> }
> static DEVICE_ATTR_RO(matrix);
>
> +static ssize_t guest_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;
> + unsigned long apid1;
> + unsigned long apqi1;
> + unsigned long napm_bits = matrix_mdev->shadow_apcb.apm_max + 1;
> + unsigned long naqm_bits = matrix_mdev->shadow_apcb.aqm_max + 1;
> + int nchars = 0;
> + int n;
> +
> + if (!vfio_ap_mdev_has_crycb(matrix_mdev))
> + return -ENODEV;
> +
> + apid1 = find_first_bit_inv(matrix_mdev->shadow_apcb.apm, napm_bits);
> + apqi1 = find_first_bit_inv(matrix_mdev->shadow_apcb.aqm, naqm_bits);
> +
> + mutex_lock(&matrix_dev->lock);
> +
> + if ((apid1 < napm_bits) && (apqi1 < naqm_bits)) {
> + for_each_set_bit_inv(apid, matrix_mdev->shadow_apcb.apm,
> + napm_bits) {
> + for_each_set_bit_inv(apqi,
> + matrix_mdev->shadow_apcb.aqm,
> + naqm_bits) {
> + n = sprintf(bufpos, "%02lx.%04lx\n", apid,
> + apqi);
> + bufpos += n;
> + nchars += n;
> + }
> + }
> + } else if (apid1 < napm_bits) {
> + for_each_set_bit_inv(apid, matrix_mdev->shadow_apcb.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->shadow_apcb.aqm,
> + naqm_bits) {
> + n = sprintf(bufpos, ".%04lx\n", apqi);
> + bufpos += n;
> + nchars += n;
> + }
> + }
> +
> + mutex_unlock(&matrix_dev->lock);
> +
> + return nchars;
> +}

This basically looks like a version of matrix_show() operating on the
shadow apcb. I'm wondering if we could consolidate these two functions
by passing in the structure to operate on as a parameter? Might not be
worth the effort, though.