From: Pierre Morel <pmorel@linux.ibm.com>
To: Tony Krowiak <akrowiak@linux.ibm.com>,
linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org
Cc: freude@linux.ibm.com, borntraeger@de.ibm.com, cohuck@redhat.com,
mjrosato@linux.ibm.com, pasic@linux.ibm.com,
alex.williamson@redhat.com, kwankhede@nvidia.com,
jjherne@linux.ibm.com, fiuczy@linux.ibm.com
Subject: Re: [PATCH v7 03/15] s390/zcrypt: driver callback to indicate resource in use
Date: Tue, 28 Apr 2020 10:09:09 +0200 [thread overview]
Message-ID: <3f7f57fb-c137-4854-3cb0-b234196a9f1e@linux.ibm.com> (raw)
In-Reply-To: <162f7dbc-9dd0-0a42-0d1a-8412a9a848e7@linux.ibm.com>
On 2020-04-28 00:24, Tony Krowiak wrote:
>
>
> On 4/27/20 4:20 AM, Pierre Morel wrote:
>>
>>
>> On 2020-04-07 21:20, Tony Krowiak wrote:
>>> Introduces a new driver callback to prevent a root user from unbinding
>>> an AP queue from its device driver if the queue is in use. The intent of
>>> this callback is to provide a driver with the means to prevent a root
>>> user
>>> from inadvertently taking a queue away from a guest and giving it to the
>>> host while the guest is still using it.
...snip...
>>
>> This functionality is valid for the host as for the guests and is
>> handled automatically by the firmware with the CRYCB.
>> The AP bus uses QCI to retrieve the host CRYCB and build the hosts AP
>> queues.
>>
>> If instead to mix VFIO CRYCB matrix handling and queues at the same
>> level inside the AP bus we separate these different firmware entities
>> in two different software entities.
>>
>> If we make the AP bus sit above a CRYCB/Matrix bus, and in the way
>> virtualize the QCI and test AP queue instructions:
>> - we can directly pass a matrix device to the guest though a VFIO
>> matrix device
>> - the consistence will be automatic
>> - the VFIO device and parent device will be of the same kind which
>> would make the design much more clearer.
>> - there will be no need for these callback because the consistence of
>> the matrix will be guaranteed by firmware
>
> As stated in my response above, the issue here is not consistency. While
> the design you describe
> may be reasonable, it is a major departure from what is out in the
> field. In other words, that ship
> has sailed.
The current VFIO-AP driver works as before, without any change, above
the Matrix device I suggest.
Aside the old scheme which can continue, the Matrix device can be used
directly to build a VFIO Matrix device, usable by QEMU without any
modification.
Once the dynamic extensions proposed in this series and the associated
tools are out on the field, then yes the ship is really far.
For now, the existing user's API do not change, the existing tools do
not need modifications and we can repair the ship for its long journey.
The inconsistency between device and VFIO device and the resulting
complexity is not going to ease future enhancement.
Regards,
Pierre
--
Pierre Morel
IBM Lab Boeblingen
next prev parent reply other threads:[~2020-04-28 8:09 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-07 19:20 [PATCH v7 00/15] s390/vfio-ap: dynamic configuration support Tony Krowiak
2020-04-07 19:20 ` [PATCH v7 01/15] s390/vfio-ap: store queue struct in hash table for quick access Tony Krowiak
2020-04-08 10:48 ` Cornelia Huck
2020-04-08 15:38 ` Tony Krowiak
2020-04-08 16:27 ` Cornelia Huck
2020-04-08 16:34 ` Tony Krowiak
2020-04-24 3:57 ` Halil Pasic
2020-04-27 13:05 ` Harald Freudenberger
2020-04-27 15:17 ` Halil Pasic
2020-04-27 21:48 ` Tony Krowiak
2020-04-28 10:07 ` Halil Pasic
2020-04-28 10:57 ` Harald Freudenberger
2020-04-28 22:30 ` Tony Krowiak
2020-04-29 7:56 ` Harald Freudenberger
2020-04-29 11:30 ` Halil Pasic
2020-04-28 10:46 ` Harald Freudenberger
2020-04-07 19:20 ` [PATCH v7 02/15] s390/vfio-ap: manage link between queue struct and matrix mdev Tony Krowiak
2020-04-09 15:06 ` Cornelia Huck
2020-04-10 15:32 ` Tony Krowiak
2020-04-10 15:41 ` Tony Krowiak
2020-04-07 19:20 ` [PATCH v7 03/15] s390/zcrypt: driver callback to indicate resource in use Tony Krowiak
2020-04-14 12:08 ` Cornelia Huck
2020-04-15 17:10 ` Tony Krowiak
2020-04-16 10:05 ` Cornelia Huck
2020-04-16 14:35 ` Tony Krowiak
2020-04-14 12:58 ` Cornelia Huck
2020-04-15 6:08 ` Harald Freudenberger
2020-04-16 9:33 ` Cornelia Huck
2020-04-17 13:54 ` Harald Freudenberger
2020-04-15 17:10 ` Tony Krowiak
2020-04-16 9:37 ` Cornelia Huck
2020-04-24 3:33 ` Halil Pasic
2020-04-24 17:07 ` Tony Krowiak
2020-04-24 18:23 ` Halil Pasic
2020-04-27 21:36 ` Tony Krowiak
2020-04-27 8:20 ` Pierre Morel
2020-04-27 22:24 ` Tony Krowiak
2020-04-28 8:09 ` Pierre Morel [this message]
2020-04-28 11:07 ` Harald Freudenberger
2020-04-28 14:37 ` Tony Krowiak
2020-04-07 19:20 ` [PATCH v7 04/15] s390/vfio-ap: implement in-use callback for vfio_ap driver Tony Krowiak
2020-04-16 11:18 ` Cornelia Huck
2020-04-16 14:45 ` Tony Krowiak
2020-04-17 11:23 ` Pierre Morel
2020-04-24 3:13 ` Halil Pasic
2020-04-24 16:58 ` Tony Krowiak
2020-04-07 19:20 ` [PATCH v7 05/15] s390/vfio-ap: introduce shadow CRYCB Tony Krowiak
2020-04-16 11:58 ` Cornelia Huck
2020-04-21 21:39 ` Tony Krowiak
2020-04-07 19:20 ` [PATCH v7 06/15] s390/vfio-ap: sysfs attribute to display the guest CRYCB Tony Krowiak
2020-04-08 10:33 ` Cornelia Huck
2020-04-08 16:38 ` Tony Krowiak
2020-04-08 16:46 ` Cornelia Huck
2020-04-09 14:18 ` Tony Krowiak
2020-04-07 19:20 ` [PATCH v7 07/15] s390/vfio-ap: filter CRYCB bits for unavailable queue devices Tony Krowiak
2020-04-07 19:20 ` [PATCH v7 08/15] s390/vfio_ap: add qlink from ap_matrix_mdev struct to vfio_ap_queue struct Tony Krowiak
2020-04-07 19:20 ` [PATCH v7 09/15] s390/vfio-ap: allow assignment of unavailable AP queues to mdev device Tony Krowiak
2020-04-07 19:20 ` [PATCH v7 10/15] s390/vfio-ap: allow configuration of matrix mdev in use by a KVM guest Tony Krowiak
2020-04-07 19:20 ` [PATCH v7 11/15] s390/vfio-ap: allow hot plug/unplug of AP resources using mdev device Tony Krowiak
2020-04-07 19:20 ` [PATCH v7 12/15] s390/zcrypt: Notify driver on config changed and scan complete callbacks Tony Krowiak
2020-04-07 19:20 ` [PATCH v7 13/15] s390/vfio-ap: handle host AP config change notification Tony Krowiak
2020-04-07 19:20 ` [PATCH v7 14/15] s390/vfio-ap: handle AP bus scan completed notification Tony Krowiak
2020-04-07 19:20 ` [PATCH v7 15/15] s390/vfio-ap: handle probe/remove not due to host AP config changes Tony Krowiak
2020-05-07 15:03 ` [PATCH v7 03/15] s390/zcrypt: driver callback to indicate resource in use Tony Krowiak
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