From: Pierre Morel <pmorel@linux.ibm.com>
To: Cornelia Huck <cohuck@redhat.com>
Cc: borntraeger@de.ibm.com, alex.williamson@redhat.com,
linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
kvm@vger.kernel.org, frankja@linux.ibm.com,
akrowiak@linux.ibm.com, pasic@linux.ibm.com, david@redhat.com,
schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com,
freude@linux.ibm.com, mimu@linux.ibm.com
Subject: Re: [PATCH v3 1/9] s390: vfio_ap: link the vfio_ap devices to the vfio_ap bus subsystem
Date: Thu, 14 Feb 2019 16:47:30 +0100 [thread overview]
Message-ID: <9403117a-04a6-8f69-2a61-f96d35a59555@linux.ibm.com> (raw)
In-Reply-To: <20190214155441.087d2a68.cohuck@redhat.com>
On 14/02/2019 15:54, Cornelia Huck wrote:
> On Thu, 14 Feb 2019 14:51:01 +0100
> Pierre Morel <pmorel@linux.ibm.com> wrote:
>
>> Libudev relies on having a subsystem link for non-root devices. To
>> avoid libudev (and potentially other userspace tools) choking on the
>> matrix device let us introduce a vfio_ap bus and with that the vfio_ap
>> bus subsytem, and make the matrix device reside within it.
>
> How does libudev choke on this? It feels wrong to introduce a bus that
> basically does nothing...
Christian answered this in another thread, so I don't answer.
>
>>
>> We restrict the number of allowed devices to a single one.
>>
...snip...
>> +++ b/drivers/s390/crypto/vfio_ap_drv.c
>> @@ -24,8 +24,9 @@ MODULE_LICENSE("GPL v2");
>>
>> static struct ap_driver vfio_ap_drv;
>>
>> -static struct device_type vfio_ap_dev_type = {
>> - .name = VFIO_AP_DEV_TYPE_NAME,
>> +struct matrix_driver {
>> + struct device_driver drv;
>> + int device_count;
>
> This counter basically ensures that at most one device may bind with
> this driver... you'd still have that device on the bus, though.
yes, this is what is wanted: this driver can only support one device.
May be another matrix driver can support one or more other devices.
I should update comment message my be.
>
>> };
>>
>> struct ap_matrix_dev *matrix_dev;
>>
>> - 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;
>> + matrix_dev->device.bus = &matrix_bus;
>> matrix_dev->device.release = vfio_ap_matrix_dev_release;
>> - matrix_dev->device.driver = &vfio_ap_drv.driver;
>> + matrix_dev->vfio_ap_drv = &vfio_ap_drv;
>
> Can't you get that structure through matrix_dev->device.driver instead
> when you need it in the function below?
Not anymore.
We have two different drivers and devices
matrix_drv <-> matrix_dev
and
vfio_ap_drv <-> ap_devices
The driver behind the matrix_dev->dev->driver is matrix_drv
what is needed here is vfio_ap_drv.
>
>>
>> ret = device_register(&matrix_dev->device);
>> if (ret)
>> goto matrix_reg_err;
>>
>> + ret = driver_register(&matrix_driver.drv);
>> + if (ret)
>> + goto matrix_drv_err;
>> +
>
> As you already have several structures that can be registered exactly
> once (the root device, the bus, the driver, ...), you can already be
> sure that there's only one device on the bus, can't you?
hum, no I don't think so, no device can register before this module is
loaded, but what does prevent a device to register later from another
module?
--
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany
next prev parent reply other threads:[~2019-02-14 15:47 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-14 13:51 [PATCH v3 0/9] [RFC] vfio: ap: ioctl definitions for AP Queue Interrupt Control Pierre Morel
2019-02-14 13:51 ` [PATCH v3 1/9] s390: vfio_ap: link the vfio_ap devices to the vfio_ap bus subsystem Pierre Morel
2019-02-14 14:54 ` Cornelia Huck
2019-02-14 15:05 ` Christian Borntraeger
2019-02-14 15:40 ` Cornelia Huck
2019-02-14 17:12 ` Tony Krowiak
2019-02-14 17:35 ` Pierre Morel
2019-02-14 15:47 ` Pierre Morel [this message]
2019-02-14 16:57 ` Cornelia Huck
2019-02-14 17:36 ` Pierre Morel
2019-02-14 18:30 ` Tony Krowiak
2019-02-15 9:11 ` Cornelia Huck
2019-02-15 21:59 ` Tony Krowiak
2019-02-18 12:01 ` Cornelia Huck
2019-02-18 16:35 ` Tony Krowiak
2019-02-18 16:57 ` Cornelia Huck
2019-02-19 22:27 ` Tony Krowiak
2019-02-20 9:05 ` Cornelia Huck
2019-02-14 15:01 ` Christian Borntraeger
2019-02-14 15:09 ` Pierre Morel
2019-02-14 13:51 ` [PATCH v3 2/9] s390: ap: kvm: setting a hook for PQAP instructions Pierre Morel
2019-02-14 15:54 ` Cornelia Huck
2019-02-14 16:45 ` Pierre Morel
2019-02-15 9:26 ` Cornelia Huck
2019-02-15 9:55 ` Pierre Morel
2019-02-15 22:02 ` Tony Krowiak
2019-02-18 18:29 ` Pierre Morel
2019-02-18 22:42 ` Cornelia Huck
2019-02-19 19:50 ` Pierre Morel
2019-02-19 22:36 ` Tony Krowiak
2019-02-21 12:40 ` Pierre Morel
2019-02-19 22:50 ` Tony Krowiak
2019-02-14 13:51 ` [PATCH v3 3/9] s390: ap: new vfio_ap_queue structure Pierre Morel
2019-02-15 9:37 ` Cornelia Huck
2019-02-15 9:58 ` Pierre Morel
2019-02-14 13:51 ` [PATCH v3 4/9] s390: ap: tools to find a queue with a specific APQN Pierre Morel
2019-02-15 9:49 ` Cornelia Huck
2019-02-15 10:10 ` Pierre Morel
2019-02-15 10:24 ` Cornelia Huck
2019-02-15 22:13 ` Tony Krowiak
2019-02-18 12:21 ` Cornelia Huck
2019-02-18 18:32 ` Pierre Morel
2019-02-22 15:04 ` Tony Krowiak
2019-02-14 13:51 ` [PATCH v3 5/9] s390: ap: tools to associate a queue to a matrix Pierre Morel
2019-02-15 22:30 ` Tony Krowiak
2019-02-18 18:36 ` Pierre Morel
2019-02-14 13:51 ` [PATCH v3 6/9] vfio: ap: register IOMMU VFIO notifier Pierre Morel
2019-02-15 22:55 ` Tony Krowiak
2019-02-19 9:59 ` Halil Pasic
2019-02-19 19:04 ` Pierre Morel
2019-02-19 21:33 ` Tony Krowiak
2019-02-19 18:51 ` Pierre Morel
2019-02-14 13:51 ` [PATCH v3 7/9] s390: ap: implement PAPQ AQIC interception in kernel Pierre Morel
2019-02-15 23:11 ` Tony Krowiak
2019-02-19 19:16 ` Pierre Morel
2019-02-20 11:54 ` Halil Pasic
2019-02-21 12:50 ` Pierre Morel
2019-02-14 13:51 ` [PATCH v3 8/9] s390: ap: Cleanup on removing the AP device Pierre Morel
2019-02-15 23:29 ` Tony Krowiak
2019-02-19 19:29 ` Pierre Morel
2019-02-15 23:36 ` Tony Krowiak
2019-02-19 19:41 ` Pierre Morel
2019-02-14 13:51 ` [PATCH v3 9/9] s390: ap: kvm: add AP Queue Interruption Control facility Pierre Morel
2019-02-14 20:33 ` [PATCH v3 0/9] [RFC] vfio: ap: ioctl definitions for AP Queue Interrupt Control Tony Krowiak
2019-02-15 8:44 ` Pierre Morel
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