linux-kernel - Re: [PATCH v10 05/26] s390: vfio-ap: register matrix device with VFIO mdev framework

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Date:   Thu, 20 Sep 2018 16:35:07 -0400
From:   Tony Krowiak <akrowiak@...ux.ibm.com>
To:     Cornelia Huck <cohuck@...hat.com>,
        Tony Krowiak <akrowiak@...ux.vnet.ibm.com>
Cc:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, freude@...ibm.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, borntraeger@...ibm.com,
        kwankhede@...dia.com, bjsdjshi@...ux.vnet.ibm.com,
        pbonzini@...hat.com, alex.williamson@...hat.com,
        pmorel@...ux.vnet.ibm.com, alifm@...ux.vnet.ibm.com,
        mjrosato@...ux.vnet.ibm.com, jjherne@...ux.vnet.ibm.com,
        thuth@...hat.com, pasic@...ux.vnet.ibm.com, berrange@...hat.com,
        fiuczy@...ux.vnet.ibm.com, buendgen@...ibm.com,
        frankja@...ux.ibm.com
Subject: Re: [PATCH v10 05/26] s390: vfio-ap: register matrix device with VFIO
 mdev framework

On 09/20/2018 11:50 AM, Cornelia Huck wrote:
> On Wed, 12 Sep 2018 15:42:55 -0400
> Tony Krowiak <akrowiak@...ux.vnet.ibm.com> wrote:
>
>> From: Tony Krowiak <akrowiak@...ux.ibm.com>
>>
>> Registers the matrix device created by the VFIO AP device
>> driver with the VFIO mediated device framework.
>> Registering the matrix device will create the sysfs
>> structures needed to create mediated matrix devices
>> each of which will be used to configure the AP matrix
>> for a guest and connect it to the VFIO AP device driver.
>>
>> Registering the matrix device with the VFIO mediated device
>> framework will create the following sysfs structures:
>>
>> /sys/devices/vfio_ap/matrix/
>> ...... [mdev_supported_types]
>> ......... [vfio_ap-passthrough]
>> ............ create
>>
>> To create a mediated device for the AP matrix device, write a UUID
>> to the create file:
>>
>> 	uuidgen > create
>>
>> A symbolic link to the mediated device's directory will be created in the
>> devices subdirectory named after the generated $uuid:
>>
>> /sys/devices/vfio_ap/matrix/
>> ...... [mdev_supported_types]
>> ......... [vfio_ap-passthrough]
>> ............ [devices]
>> ............... [$uuid]
>>
>> A symbolic link to the mediated device will also be created
>> in the vfio_ap matrix's directory:
>>
>> /sys/devices/vfio_ap/matrix/[$uuid]
>>
>> Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>
>> Reviewed-by: Halil Pasic <pasic@...ux.ibm.com>
>> Tested-by: Michael Mueller <mimu@...ux.ibm.com>
>> Tested-by: Farhan Ali <alifm@...ux.ibm.com>
>> Signed-off-by: Christian Borntraeger <borntraeger@...ibm.com>
>> ---
>>   MAINTAINERS                           |    1 +
>>   drivers/s390/crypto/Makefile          |    2 +-
>>   drivers/s390/crypto/vfio_ap_drv.c     |   19 +++++
>>   drivers/s390/crypto/vfio_ap_ops.c     |  126 +++++++++++++++++++++++++++++++++
>>   drivers/s390/crypto/vfio_ap_private.h |   49 +++++++++++++
>>   include/uapi/linux/vfio.h             |    1 +
>>   6 files changed, 197 insertions(+), 1 deletions(-)
>>   create mode 100644 drivers/s390/crypto/vfio_ap_ops.c
> (...)
>
>> diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
>> index 3e635f0..75f8bdc 100644
>> --- a/drivers/s390/crypto/vfio_ap_drv.c
>> +++ b/drivers/s390/crypto/vfio_ap_drv.c
>> @@ -76,6 +76,16 @@ static int vfio_ap_matrix_dev_create(void)
>>   		goto matrix_alloc_err;
>>   	}
>>   
>> +	/* Test if PQAP(QCI) instruction is available */
> /* Fill in config info via PQAP(QCI), if available */

Okay

>
> ?
>
>> +	if (test_facility(12)) {
>> +		ret = ap_qci(&matrix_dev->info);
>> +		if (ret)
>> +			goto matrix_alloc_err;
>> +	}
>> +
>> +	mutex_init(&matrix_dev->lock);
>> +	INIT_LIST_HEAD(&matrix_dev->mdev_list);
>> +
>>   	matrix_dev->device.type = &vfio_ap_dev_type;
>>   	dev_set_name(&matrix_dev->device, "%s", VFIO_AP_DEV_NAME);
>>   	matrix_dev->device.parent = root_device;
> (...)
>
>> diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
>> index 6141420..a2eab78 100644
>> --- a/drivers/s390/crypto/vfio_ap_private.h
>> +++ b/drivers/s390/crypto/vfio_ap_private.h
>> @@ -3,6 +3,7 @@
>>    * Private data and functions for adjunct processor VFIO matrix driver.
>>    *
>>    * Author(s): Tony Krowiak <akrowiak@...ux.ibm.com>
>> + *	      Halil Pasic <pasic@...ux.ibm.com>
>>    *
>>    * Copyright IBM Corp. 2018
>>    */
>> @@ -24,11 +25,59 @@
>>   /**
>>    * ap_matrix_dev - the AP matrix device structure
>>    * @device:	generic device structure associated with the AP matrix device
>> + * @available_instances: number of mediated matrix devices that can be created
>> + * @info:	the struct containing the output from the PQAP(TAPQ) instruction
> Hm, isn't that rather PQAP(QCI)?

Yes it is!

>
>> + * mdev_list:	the list of mediated matrix devices created
>> + * lock:	mutex for locking the AP matrix device. This lock will be
>> + *		taken every time we fiddle with state managed by the vfio_ap
>> + *		driver, be it using @mdev_list or writing the state of a
>> + *		single ap_matrix_mdev device. It's quite coarse but we don't
>> + *		expect much contention.
>>    */
>>   struct ap_matrix_dev {
>>   	struct device device;
>> +	atomic_t available_instances;
>> +	struct ap_config_info info;
>> +	struct list_head mdev_list;
>> +	struct mutex lock;
>>   };
> Otherwise:
> Reviewed-by: Cornelia Huck <cohuck@...hat.com>
>