Re: [PATCH v8 09/22] s390: vfio-ap: register matrix device with VFIO mdev framework

Pierre Morel
2018-08-09T16:27:16Z

On 09/08/2018 13:06, Cornelia Huck wrote:
> On Wed, 8 Aug 2018 10:44:19 -0400
> Tony Krowiak <akrowiak@linux.vnet.ibm.com> wrote:
>
>> diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
>> index d7e39ad..6a827f3 100644
>> --- a/drivers/s390/crypto/vfio_ap_drv.c
>> +++ b/drivers/s390/crypto/vfio_ap_drv.c
>> @@ -12,6 +12,7 @@
>> #include <linux/mod_devicetable.h>
>> #include <linux/slab.h>
>> #include <linux/string.h>
>> +#include <asm/zcrypt.h>
>> #include "vfio_ap_private.h"
>>
>> #define VFIO_AP_ROOT_NAME "vfio_ap"
>> @@ -68,6 +69,18 @@ static int vfio_ap_matrix_dev_create(void)
>> {
>> int ret;
>>
>> + mutex_init(&matrix_dev.lock);
>> + INIT_LIST_HEAD(&matrix_dev.mdev_list);
>> +
>> + /* Test if PQAP(QCI) instruction is available */
>> + if (test_facility(12)) {
>> + ret = ap_qci(&matrix_dev.info);
>> + if (ret)
>> + return ret;
>> + }
>> +
>> + atomic_set(&matrix_dev.available_instances, MAX_ZDEV_ENTRIES_EXT);
>> +
>> ret = misc_register(&matrix_dev.misc_dev);
> OK, you are adding more stuff other than the miscdevice after all...
> still, I don't think that this is a good idea.
>
> I think I had already asked this for a previous version: Why has this
> been turned into a miscdevice? (I think my reaction to the answer was
> 'meh'... but I think more and more that we should not do that.)

Following our off-line conversation...

I understand your concern, about the misc device and dynamically
updating the misc device structure.

For it is your main point of contention and we do not currently have
a use case for the misc device I propose we just let it go and
rebase on the device design we had in V6 and did not seem to
make any trouble to any one.

We will propose a v9 with the integration of all comment done
so far soon as possible.

Best regards,

Pierre

>
>> if (ret)
>> return ret;

--
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany