From: Yan Zhao <yan.y.zhao@intel.com>
To: Jason Wang <jasowang@redhat.com>
Cc: "Cornelia Huck" <cohuck@redhat.com>,
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Subject: Re: [ovirt-devel] Re: device compatibility interface for live migration with assigned devices
Date: Wed, 19 Aug 2020 16:13:39 +0800 [thread overview]
Message-ID: <20200819081338.GC21172@joy-OptiPlex-7040> (raw)
In-Reply-To: <d6f9a51e-80b3-44c5-2656-614b327dc080@redhat.com>
On Wed, Aug 19, 2020 at 03:39:50PM +0800, Jason Wang wrote:
>
> 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
>
So, what's different for it vs passing through a physical hardware via VFIO?
even though the features are negotiated dynamically, could you explain
why it would cause software_version not work?
>
> > 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?
that's why some attributes need to be common. e.g.
device_api: it's common because mgmt need to know it's a pci device or a
ccw device. and the api type is already defined vfio.h.
(The field is agreed by and actually suggested by Alex in previous mail)
type: mdev_type for mdev. if mgmt does not understand it, it would not
be able to create one compatible mdev device.
software_version: mgmt can compare the major and minor if it understands
this fields.
>
>
> >
> > > > - 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.
>
yes, it's just NVMe specific. I added it as an example to show what is
vendor specific.
if one attribute is vendor specific across all vendors, then it's not vendor specific,
it's already common attribute, right?
> The point is that if vendor/class specific part is unavoidable, why not
> making all of the attributes vendor specific?
>
some parts need to be common, as I listed above.
>
> > 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.
>
some Intel devices have bitmask based capability registers.
so what?
we have defined pci_id to identify the devices.
even two different devices have equal PCI IDs, we still allow them to
add vendor specific fields. e.g.
for QAT, they can add alg_set to identify hardware supported algorithms.
>
> >
> > > - 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)?
>
if the device is binding to vfio or vfio-mdev, I believe this interface
is not there.
Thanks
Yan
next prev parent reply other threads:[~2020-08-19 8:33 UTC|newest]
Thread overview: 118+ 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 7:37 ` Alex Xu
2020-07-17 15:18 ` Alex Williamson
2020-07-15 8:20 ` Yan Zhao
2020-07-15 8:49 ` Feng, Shaohe
2020-07-15 9:21 ` Alex Xu
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
2020-07-15 7:23 ` Alex Xu
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
2020-08-19 8:13 ` Yan Zhao [this message]
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
2020-09-15 7:46 ` Zeng, Xin
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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