From: Jason Wang <jasowang@redhat.com>
To: Yan Zhao <yan.y.zhao@intel.com>
Cc: "Parav Pandit" <parav@nvidia.com>,
"Cornelia Huck" <cohuck@redhat.com>,
"Daniel P. Berrangé" <berrange@redhat.com>,
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"Kirti Wankhede" <kwankhede@nvidia.com>,
"eauger@redhat.com" <eauger@redhat.com>,
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"corbet@lwn.net" <corbet@lwn.net>,
"openstack-discuss@lists.openstack.org"
<openstack-discuss@lists.openstack.org>,
"shaohe.feng@intel.com" <shaohe.feng@intel.com>,
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"Parav Pandit" <parav@mellanox.com>,
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"Alex Williamson" <alex.williamson@redhat.com>,
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"devel@ovirt.org" <devel@ovirt.org>
Subject: Re: [ovirt-devel] Re: device compatibility interface for live migration with assigned devices
Date: Wed, 19 Aug 2020 15:39:50 +0800 [thread overview]
Message-ID: <d6f9a51e-80b3-44c5-2656-614b327dc080@redhat.com> (raw)
In-Reply-To: <20200819065951.GB21172@joy-OptiPlex-7040>
On 2020/8/19 下午2:59, Yan Zhao wrote:
> On Wed, Aug 19, 2020 at 02:57:34PM +0800, Jason Wang wrote:
>> On 2020/8/19 上午11:30, Yan Zhao wrote:
>>> hi All,
>>> could we decide that sysfs is the interface that every VFIO vendor driver
>>> needs to provide in order to support vfio live migration, otherwise the
>>> userspace management tool would not list the device into the compatible
>>> list?
>>>
>>> if that's true, let's move to the standardizing of the sysfs interface.
>>> (1) content
>>> common part: (must)
>>> - software_version: (in major.minor.bugfix scheme)
>>
>> This can not work for devices whose features can be negotiated/advertised
>> independently. (E.g virtio devices)
>>
> sorry, I don't understand here, why virtio devices need to use vfio interface?
I don't see any reason that virtio devices can't be used by VFIO. Do you?
Actually, virtio devices have been used by VFIO for many years:
- passthrough a hardware virtio devices to userspace(VM) drivers
- using virtio PMD inside guest
> I think this thread is discussing about vfio related devices.
>
>>> - device_api: vfio-pci or vfio-ccw ...
>>> - type: mdev type for mdev device or
>>> a signature for physical device which is a counterpart for
>>> mdev type.
>>>
>>> device api specific part: (must)
>>> - pci id: pci id of mdev parent device or pci id of physical pci
>>> device (device_api is vfio-pci)API here.
>>
>> So this assumes a PCI device which is probably not true.
>>
> for device_api of vfio-pci, why it's not true?
>
> for vfio-ccw, it's subchannel_type.
Ok but having two different attributes for the same file is not good
idea. How mgmt know there will be a 3rd type?
>
>>> - subchannel_type (device_api is vfio-ccw)
>>> vendor driver specific part: (optional)
>>> - aggregator
>>> - chpid_type
>>> - remote_url
>>
>> For "remote_url", just wonder if it's better to integrate or reuse the
>> existing NVME management interface instead of duplicating it here. Otherwise
>> it could be a burden for mgmt to learn. E.g vendor A may use "remote_url"
>> but vendor B may use a different attribute.
>>
> it's vendor driver specific.
> vendor specific attributes are inevitable, and that's why we are
> discussing here of a way to standardizing of it.
Well, then you will end up with a very long list to discuss. E.g for
networking devices, you will have "mac", "v(x)lan" and a lot of other.
Note that "remote_url" is not vendor specific but NVME (class/subsystem)
specific.
The point is that if vendor/class specific part is unavoidable, why not
making all of the attributes vendor specific?
> our goal is that mgmt can use it without understanding the meaning of vendor
> specific attributes.
I'm not sure this is the correct design of uAPI. Is there something
similar in the existing uAPIs?
And it might be hard to work for virtio devices.
>
>>> NOTE: vendors are free to add attributes in this part with a
>>> restriction that this attribute is able to be configured with the same
>>> name in sysfs too. e.g.
>>
>> Sysfs works well for common attributes belongs to a class, but I'm not sure
>> it can work well for device/vendor specific attributes. Does this mean mgmt
>> need to iterate all the attributes in both src and dst?
>>
> no. just attributes under migration directory.
>
>>> for aggregator, there must be a sysfs attribute in device node
>>> /sys/devices/pci0000:00/0000:00:02.0/882cc4da-dede-11e7-9180-078a62063ab1/intel_vgpu/aggregator,
>>> so that the userspace tool is able to configure the target device
>>> according to source device's aggregator attribute.
>>>
>>>
>>> (2) where and structure
>>> proposal 1:
>>> |- [path to device]
>>> |--- migration
>>> | |--- self
>>> | | |-software_version
>>> | | |-device_api
>>> | | |-type
>>> | | |-[pci_id or subchannel_type]
>>> | | |-<aggregator or chpid_type>
>>> | |--- compatible
>>> | | |-software_version
>>> | | |-device_api
>>> | | |-type
>>> | | |-[pci_id or subchannel_type]
>>> | | |-<aggregator or chpid_type>
>>> multiple compatible is allowed.
>>> attributes should be ASCII text files, preferably with only one value
>>> per file.
>>>
>>>
>>> proposal 2: use bin_attribute.
>>> |- [path to device]
>>> |--- migration
>>> | |--- self
>>> | |--- compatible
>>>
>>> so we can continue use multiline format. e.g.
>>> cat compatible
>>> software_version=0.1.0
>>> device_api=vfio_pci
>>> type=i915-GVTg_V5_{val1:int:1,2,4,8}
>>> pci_id=80865963
>>> aggregator={val1}/2
>>
>> So basically two questions:
>>
>> - how hard to standardize sysfs API for dealing with compatibility check (to
>> make it work for most types of devices)
> sorry, I just know we are in the process of standardizing of it :)
It's not easy. As I said, the current design can't work for virtio
devices and it's not hard to find other examples. I remember some Intel
devices have bitmask based capability registers.
>
>> - how hard for the mgmt to learn with a vendor specific attributes (vs
>> existing management API)
> what is existing management API?
It depends on the type of devices. E.g for NVME, we've already had one
(/sys/kernel/config/nvme)?
Thanks
>
> Thanks
>
next prev parent reply other threads:[~2020-08-19 7:40 UTC|newest]
Thread overview: 114+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-13 23:29 device compatibility interface for live migration with assigned devices Yan Zhao
2020-07-14 10:21 ` Daniel P. Berrangé
2020-07-14 12:33 ` Sean Mooney
[not found] ` <20200714110148.0471c03c@x1.home>
[not found] ` <eb705c72cdc8b6b8959b6ebaeeac6069a718d524.camel@redhat.com>
2020-07-14 21:15 ` Sean Mooney
2020-07-14 16:16 ` Alex Williamson
2020-07-14 16:47 ` Daniel P. Berrangé
2020-07-14 20:47 ` Alex Williamson
2020-07-15 9:16 ` Daniel P. Berrangé
2020-07-14 17:19 ` Dr. David Alan Gilbert
2020-07-14 20:59 ` Alex Williamson
2020-07-15 8:20 ` Yan Zhao
2020-07-15 8:49 ` Feng, Shaohe
2020-07-17 14:59 ` Alex Williamson
2020-07-17 18:03 ` Dr. David Alan Gilbert
2020-07-17 18:30 ` Alex Williamson
2020-07-15 8:23 ` Dr. David Alan Gilbert
[not found] ` <CAH7mGatPWsczh_rbVhx4a+psJXvkZgKou3r5HrEQTqE7SqZkKA@mail.gmail.com>
2020-07-17 15:18 ` Alex Williamson
2020-07-16 4:16 ` Jason Wang
2020-07-16 8:32 ` Yan Zhao
2020-07-16 9:30 ` Jason Wang
2020-07-17 16:12 ` Alex Williamson
2020-07-20 3:41 ` Jason Wang
2020-07-20 10:39 ` Sean Mooney
2020-07-21 2:11 ` Jason Wang
2020-07-21 0:51 ` Yan Zhao
2020-07-27 7:24 ` Yan Zhao
2020-07-27 22:23 ` Alex Williamson
2020-07-29 8:05 ` Yan Zhao
2020-07-29 11:28 ` Sean Mooney
2020-07-29 19:12 ` Alex Williamson
2020-07-30 3:41 ` Yan Zhao
2020-07-30 13:24 ` Sean Mooney
2020-07-30 17:29 ` Alex Williamson
2020-08-04 8:37 ` Yan Zhao
2020-08-05 9:44 ` Dr. David Alan Gilbert
2020-07-30 1:56 ` Yan Zhao
2020-07-30 13:14 ` Sean Mooney
2020-08-04 16:35 ` Cornelia Huck
2020-08-05 2:22 ` Jason Wang
2020-08-05 2:16 ` Yan Zhao
2020-08-05 2:41 ` Jason Wang
2020-08-05 7:56 ` Jiri Pirko
2020-08-05 8:02 ` Jason Wang
2020-08-05 9:33 ` Yan Zhao
2020-08-05 10:53 ` Jiri Pirko
2020-08-05 11:35 ` Sean Mooney
2020-08-07 11:59 ` Cornelia Huck
2020-08-13 15:33 ` Cornelia Huck
2020-08-13 19:02 ` Eric Farman
2020-08-17 6:38 ` Cornelia Huck
2020-08-10 7:46 ` Yan Zhao
2020-08-13 4:24 ` Jason Wang
2020-08-14 5:16 ` Yan Zhao
2020-08-14 12:30 ` Sean Mooney
2020-08-17 1:52 ` Yan Zhao
2020-08-18 3:24 ` Jason Wang
2020-08-18 8:55 ` Daniel P. Berrangé
2020-08-18 9:06 ` Cornelia Huck
2020-08-18 9:24 ` Daniel P. Berrangé
2020-08-18 9:38 ` Cornelia Huck
[not found] ` <3a073222-dcfe-c02d-198b-29f6a507b2e1@redhat.com>
2020-08-18 9:16 ` Daniel P. Berrangé
2020-08-18 9:36 ` Cornelia Huck
2020-08-18 9:39 ` Parav Pandit
2020-08-19 3:30 ` Yan Zhao
2020-08-19 5:58 ` Parav Pandit
2020-08-19 9:41 ` Jason Wang
2020-08-19 6:57 ` [ovirt-devel] " Jason Wang
2020-08-19 6:59 ` Yan Zhao
2020-08-19 7:39 ` Jason Wang [this message]
2020-08-19 8:13 ` Yan Zhao
2020-08-19 9:28 ` Jason Wang
2020-08-20 12:27 ` Cornelia Huck
2020-08-21 3:14 ` Jason Wang
2020-08-21 14:52 ` Cornelia Huck
2020-08-31 3:07 ` Jason Wang
2020-08-19 17:50 ` Alex Williamson
2020-08-20 0:18 ` Yan Zhao
2020-08-20 3:13 ` Alex Williamson
2020-08-20 3:09 ` Yan Zhao
2020-08-19 2:54 ` Jason Wang
2020-08-20 0:39 ` Yan Zhao
2020-08-20 1:29 ` Sean Mooney
2020-08-20 4:01 ` Yan Zhao
2020-08-20 5:16 ` Sean Mooney
2020-08-20 6:27 ` Yan Zhao
2020-08-20 13:24 ` Sean Mooney
2020-08-26 8:54 ` Yan Zhao
2020-08-20 3:22 ` Alex Williamson
2020-08-20 3:16 ` Yan Zhao
2020-08-25 14:39 ` Cornelia Huck
2020-08-26 6:41 ` Yan Zhao
2020-08-28 13:47 ` Cornelia Huck
2020-08-28 14:04 ` Sean Mooney
2020-08-31 4:43 ` Yan Zhao
2020-09-08 14:41 ` Cornelia Huck
2020-09-09 2:13 ` Yan Zhao
2020-09-10 12:38 ` Cornelia Huck
2020-09-10 12:50 ` Sean Mooney
2020-09-10 18:02 ` Alex Williamson
2020-09-11 0:56 ` Yan Zhao
2020-09-11 10:08 ` Cornelia Huck
2020-09-11 10:18 ` Tian, Kevin
2020-09-11 16:51 ` Alex Williamson
2020-09-14 13:48 ` Zeng, Xin
2020-09-14 14:44 ` Alex Williamson
2020-09-09 5:37 ` Yan Zhao
2020-08-31 2:23 ` Yan Zhao
2020-08-19 2:38 ` Jason Wang
2020-08-18 9:32 ` Parav Pandit
2020-08-19 2:45 ` Jason Wang
2020-08-19 5:26 ` Parav Pandit
2020-08-19 6:48 ` Jason Wang
2020-08-19 6:53 ` Parav Pandit
2020-07-29 19:05 ` Dr. David Alan Gilbert
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