Re: [PATCH v3 4/9] s390: ap: tools to find a queue with a specific APQN

Pierre Morel
2019-02-15T10:10:43Z

On 15/02/2019 10:49, Cornelia Huck wrote:
> On Thu, 14 Feb 2019 14:51:04 +0100
> Pierre Morel <pmorel@linux.ibm.com> wrote:
>
>> We need to find the queue with a specific APQN during the
>> handling of the interception of the PQAP/AQIC instruction.
>>
>> To handle the AP associated device reference count we keep
>> track of it in the vfio_ap_queue until we put the device.
>
> So, the relationship is
> (struct ap_device)--(driver_data)-->(struct vfio_ap_queue)--(pointer)-->(struct ap_device)
> ? IOW, a backlink?
>
> If so, can't you already set that up during probe?

Will do.

>
> Or am I confused by the various similar devices again? Maybe a diagram
> would help...

No you are right.

>
>>
>> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
>> ---
>> drivers/s390/crypto/vfio_ap_ops.c | 54 +++++++++++++++++++++++++++++++++++
>> drivers/s390/crypto/vfio_ap_private.h | 1 +
>> 2 files changed, 55 insertions(+)
>>
>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
>> index 900b9cf..2a52c9b 100644
>> --- a/drivers/s390/crypto/vfio_ap_ops.c
>> +++ b/drivers/s390/crypto/vfio_ap_ops.c
>> @@ -24,6 +24,60 @@
>> #define VFIO_AP_MDEV_TYPE_HWVIRT "passthrough"
>> #define VFIO_AP_MDEV_NAME_HWVIRT "VFIO AP Passthrough Device"
>>
>> +/**
>> + * vfio_ap_check_apqn: check if a ap_queue is of a given APQN
>> + *
>> + * Returns 1 if we have a match.
>> + * Otherwise returns 0.
>> + */
>> +static int vfio_ap_check_apqn(struct device *dev, void *data)
>> +{
>> + struct vfio_ap_queue *q = dev_get_drvdata(dev);
>> +
>> + return (q->apqn == *(int *)data);
>> +}
>> +
>> +/**
>> + * vfio_ap_get_queue: Retrieve a queue with a specific APQN
>> + * @apqn: The queue APQN
>> + *
>> + * Retrieve a queue with a specific APQN from the list of the
>> + * devices associated to the vfio_ap_driver.
>> + *
>> + * The vfio_ap_queue has been already associated with the device
>> + * during the probe.
>> + * Store the associated device for reference counting
>> + *
>> + * Returns the pointer to the associated vfio_ap_queue
>> + */
>> +static __attribute__((unused))
>
> Eww. Can you get rid of that by reordering or squashing patches?

I did this to avoid posting a very big patch.
I will of course squash 4 and 5 with patch 6, when the two patches 4 and
5 are reviewed.

If you think it brings more clarity to squash all for the next iteration
I will do.

Regards,
Pierre

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