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SubjectRe: [RFC 08/19] s390/zcrypt: support for assigning adapters to matrix mdev
On Fri, 13 Oct 2017 13:38:53 -0400
Tony Krowiak <akrowiak@linux.vnet.ibm.com> wrote:

> Provides the sysfs interfaces for assigning an adapter to
> and unassigning an AP adapter from a mediated matrix device.
>
> The IDs of the AP adapters assigned to the mediated matrix
> device are stored in a bit mask. The bits in the mask, from
> left to right, correspond to AP adapter numbers 0 to 255. The
> bit corresponding to the ID of the adapter being assigned will
> be set in the bit mask.
>
> The relevant sysfs structures are:
>
> /sys/devices/ap_matrix
> ... [matrix]
> ...... [mdev_supported_types]
> ......... [ap_matrix-passthrough]
> ............ [devices]
> ...............[$uuid]
> .................. adapters
> .................. assign_adapter
> .................. unassign_adapter
>
> To assign an adapter to the $uuid mediated matrix device, write
> ID of the adapter (hex value) to the assign_adapter file. To
> unassign an adapter, write the ID of the adapter (hex value)
> to the unassign_adapter file. The list of adapters that have
> been assigned can be viewed by displaying the contents of the
> adapters file.
>
> For example, to assign adapter 0xad to mediated matrix device
> $uuid:
>
> echo ad > assign_adapter
>
> To unassign adapter 0xad:
>
> echo ad > unassign_adapter
>
> To see the list of adapters assigned:
>
> cat adapters
>
> Signed-off-by: Tony Krowiak <akrowiak@linux.vnet.ibm.com>
> ---
> arch/s390/include/asm/ap-config.h | 13 +++
> drivers/s390/crypto/vfio_ap_matrix_ops.c | 147 ++++++++++++++++++++++++++++++
> 2 files changed, 160 insertions(+), 0 deletions(-)
>

> diff --git a/drivers/s390/crypto/vfio_ap_matrix_ops.c b/drivers/s390/crypto/vfio_ap_matrix_ops.c
> index 7d01f18..e4b1236 100644
> --- a/drivers/s390/crypto/vfio_ap_matrix_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_matrix_ops.c
> @@ -23,6 +23,7 @@
> struct ap_matrix_mdev {
> struct mdev_device *mdev;
> struct list_head node;
> + struct ap_config_masks masks;
> };
>
> struct ap_matrix *matrix;
> @@ -136,9 +137,155 @@ static ssize_t device_api_show(struct kobject *kobj, struct device *dev,
> NULL,
> };
>
> +static int ap_matrix_id_is_xnum(char *id)
> +{
> + size_t i;
> +
> + for (i = 0; i < strlen(id); i++) {
> + if (!isxdigit(id[i]))
> + return 0;
> + }
> +
> + return 1;
> +}

This feels like something for which an utility function should already
exist...

> +
> +static int ap_matrix_parse_id(const char *buf, unsigned int *id)
> +{
> + int ret;
> + char *bufcpy;
> + char *id_str;
> +
> + if ((strlen(buf) == 0) || (*buf == '\n')) {
> + pr_err("%s: input buffer '%s' contains no valid hex values",
> + VFIO_AP_MATRIX_MODULE_NAME, buf);
> + return -EINVAL;
> + }
> +
> + bufcpy = kzalloc(strlen(buf) + 1, GFP_KERNEL);
> + if (!bufcpy)
> + return -ENOMEM;
> +
> + strcpy(bufcpy, buf);
> + id_str = strim(bufcpy);
> +
> + if (!ap_matrix_id_is_xnum(id_str)) {
> + pr_err("%s: input id '%s' contains an invalid hex value '%s'",
> + VFIO_AP_MATRIX_MODULE_NAME, buf, id_str);
> + ret = -EINVAL;
> + goto done;
> + }
> +
> + ret = kstrtouint (id_str, 16, id);
> + if (ret || (*id >= AP_MATRIX_MAX_MASK_BITS)) {
> + pr_err("%s: input id '%s' is not a value from 0 to %x",
> + VFIO_AP_MATRIX_MODULE_NAME, buf,
> + AP_MATRIX_MAX_MASK_BITS);
> + ret = -EINVAL;
> + goto done;
> + }
> +
> + ret = 0;
> +
> +done:
> + kfree(bufcpy);
> + return ret;
> +}

Similarly, I suspect you are not the first person with similar parsing
needs.

> +
> +static ssize_t ap_matrix_adapters_assign(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + int ret;
> + unsigned int apid;
> + struct mdev_device *mdev = mdev_from_dev(dev);
> + struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
> +
> + ret = ap_matrix_parse_id(buf, &apid);
> + if (ret)
> + return ret;
> +
> + set_bit_inv((unsigned long)apid,
> + (unsigned long *)matrix_mdev->masks.apm);

Probably needs a comment regarding byte order of the masks somewhere.

> +
> + return count;
> +}
> +static DEVICE_ATTR(assign_adapter, 0644, NULL, ap_matrix_adapters_assign);

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