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Subject: Re: [RFC 08/19] s390/zcrypt: support for assigning adapters to matrix
 mdev
To:     Cornelia Huck <cohuck@redhat.com>
Cc:     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,
        pmorel@linux.vnet.ibm.com, alifm@linux.vnet.ibm.com,
        mjrosato@linux.vnet.ibm.com, qemu-s390x@nongnu.org,
        jjherne@linux.vnet.ibm.com, thuth@redhat.com,
        pasic@linux.vnet.ibm.com
References: <1507916344-3896-1-git-send-email-akrowiak@linux.vnet.ibm.com>
 <1507916344-3896-9-git-send-email-akrowiak@linux.vnet.ibm.com>
 <20171114142244.272d538d.cohuck@redhat.com>
From:   Tony Krowiak <akrowiak@linux.vnet.ibm.com>
Date:   Thu, 16 Nov 2017 18:53:07 -0500
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On 11/14/2017 08:22 AM, Cornelia Huck wrote:
> 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...
See comment below
>
>> +
>> +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.
I am going to remove this function
>
>> +
>> +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);
I'm going to replace this with a call to kstrtouint (buf, 0, &apid). This
will allow the user to enter the adapter ID string using conventional
semantics - e.g., 71 or  0x47 - and the function will determine if the
value is valid.
>> +	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.
Okay
>
>> +
>> +	return count;
>> +}
>> +static DEVICE_ATTR(assign_adapter, 0644, NULL, ap_matrix_adapters_assign);


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