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From: Jason Wang <jasowang@redhat.com>
To: "Tian, Kevin" <kevin.tian@intel.com>, Jason Gunthorpe <jgg@mellanox.com>
Cc: "mst@redhat.com" <mst@redhat.com>,
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	Shahaf Shuler <shahafs@mellanox.com>,
	"hanand@xilinx.com" <hanand@xilinx.com>,
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Subject: Re: [PATCH 3/5] vDPA: introduce vDPA bus
Date: Tue, 21 Jan 2020 17:41:21 +0800
Message-ID: <f27d59b7-1c91-5870-55f5-e21311fcef99@redhat.com> (raw)
In-Reply-To: <AADFC41AFE54684AB9EE6CBC0274A5D19D73EBA4@SHSMSX104.ccr.corp.intel.com>


On 2020/1/21 下午4:40, Tian, Kevin wrote:
>> From: Jason Wang <jasowang@redhat.com>
>> Sent: Friday, January 17, 2020 11:03 AM
>>
>>
>> On 2020/1/16 下午11:22, Jason Gunthorpe wrote:
>>> On Thu, Jan 16, 2020 at 08:42:29PM +0800, Jason Wang wrote:
>>>> vDPA device is a device that uses a datapath which complies with the
>>>> virtio specifications with vendor specific control path. vDPA devices
>>>> can be both physically located on the hardware or emulated by
>>>> software. vDPA hardware devices are usually implemented through PCIE
>>>> with the following types:
>>>>
>>>> - PF (Physical Function) - A single Physical Function
>>>> - VF (Virtual Function) - Device that supports single root I/O
>>>>     virtualization (SR-IOV). Its Virtual Function (VF) represents a
>>>>     virtualized instance of the device that can be assigned to different
>>>>     partitions
>>>> - VDEV (Virtual Device) - With technologies such as Intel Scalable
>>>>     IOV, a virtual device composed by host OS utilizing one or more
>>>>     ADIs.
> the concept of VDEV includes both software bits and ADIs. If you
> only take about hardware types, using ADI is more accurate.


Ok.


>
>>>> - SF (Sub function) - Vendor specific interface to slice the Physical
>>>>     Function to multiple sub functions that can be assigned to different
>>>>     partitions as virtual devices.
>>> I really hope we don't end up with two different ways to spell this
>>> same thing.
>>
>> I think you meant ADI vs SF. It looks to me that ADI is limited to the
>> scope of scalable IOV but SF not.
> ADI is just a term for minimally assignable resource in Scalable IOV.
> 'assignable' implies several things, e.g. the resource can be independently
> mapped to/accessed by user space or guest, DMAs between two
> ADIs are isolated, operating one ADI doesn't affecting another ADI,
> etc.  I'm not clear about  other vendor specific interfaces, but supposing
> they need match the similar requirements. Then do we really want to
> differentiate ADI vs. SF? What about merging them with ADI as just
> one example of finer-grained slicing?


I think so. That what Jason G want as well.

Thanks


>
>>
>>>> @@ -0,0 +1,2 @@
>>>> +# SPDX-License-Identifier: GPL-2.0
>>>> +obj-$(CONFIG_VDPA) += vdpa.o
>>>> diff --git a/drivers/virtio/vdpa/vdpa.c b/drivers/virtio/vdpa/vdpa.c
>>>> new file mode 100644
>>>> index 000000000000..2b0e4a9f105d
>>>> +++ b/drivers/virtio/vdpa/vdpa.c
>>>> @@ -0,0 +1,141 @@
>>>> +// SPDX-License-Identifier: GPL-2.0-only
>>>> +/*
>>>> + * vDPA bus.
>>>> + *
>>>> + * Copyright (c) 2019, Red Hat. All rights reserved.
>>>> + *     Author: Jason Wang <jasowang@redhat.com>
>>> 2020 tests days
>>
>> Will fix.
>>
>>
>>>> + *
>>>> + */
>>>> +
>>>> +#include <linux/module.h>
>>>> +#include <linux/idr.h>
>>>> +#include <linux/vdpa.h>
>>>> +
>>>> +#define MOD_VERSION  "0.1"
>>> I think module versions are discouraged these days
>>
>> Will remove.
>>
>>
>>>> +#define MOD_DESC     "vDPA bus"
>>>> +#define MOD_AUTHOR   "Jason Wang <jasowang@redhat.com>"
>>>> +#define MOD_LICENSE  "GPL v2"
>>>> +
>>>> +static DEFINE_IDA(vdpa_index_ida);
>>>> +
>>>> +struct device *vdpa_get_parent(struct vdpa_device *vdpa)
>>>> +{
>>>> +	return vdpa->dev.parent;
>>>> +}
>>>> +EXPORT_SYMBOL(vdpa_get_parent);
>>>> +
>>>> +void vdpa_set_parent(struct vdpa_device *vdpa, struct device *parent)
>>>> +{
>>>> +	vdpa->dev.parent = parent;
>>>> +}
>>>> +EXPORT_SYMBOL(vdpa_set_parent);
>>>> +
>>>> +struct vdpa_device *dev_to_vdpa(struct device *_dev)
>>>> +{
>>>> +	return container_of(_dev, struct vdpa_device, dev);
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(dev_to_vdpa);
>>>> +
>>>> +struct device *vdpa_to_dev(struct vdpa_device *vdpa)
>>>> +{
>>>> +	return &vdpa->dev;
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(vdpa_to_dev);
>>> Why these trivial assessors? Seems unnecessary, or should at least be
>>> static inlines in a header
>>
>> Will fix.
>>
>>
>>>> +int register_vdpa_device(struct vdpa_device *vdpa)
>>>> +{
>>> Usually we want to see symbols consistently prefixed with vdpa_*, is
>>> there a reason why register/unregister are swapped?
>>
>> I follow the name from virtio. I will switch to vdpa_*.
>>
>>
>>>> +	int err;
>>>> +
>>>> +	if (!vdpa_get_parent(vdpa))
>>>> +		return -EINVAL;
>>>> +
>>>> +	if (!vdpa->config)
>>>> +		return -EINVAL;
>>>> +
>>>> +	err = ida_simple_get(&vdpa_index_ida, 0, 0, GFP_KERNEL);
>>>> +	if (err < 0)
>>>> +		return -EFAULT;
>>>> +
>>>> +	vdpa->dev.bus = &vdpa_bus;
>>>> +	device_initialize(&vdpa->dev);
>>> IMHO device_initialize should not be called inside something called
>>> register, toooften we find out that the caller drivers need the device
>>> to be initialized earlier, ie to use the kref, or something.
>>>
>>> I find the best flow is to have some init function that does the
>>> device_initialize and sets the device_name that the driver can call
>>> early.
>>
>> Ok, will do.
>>
>>
>>> Shouldn't there be a device/driver matching process of some kind?
>>
>> The question is what do we want do match here.
>>
>> 1) "virtio" vs "vhost", I implemented matching method for this in mdev
>> series, but it looks unnecessary for vDPA device driver to know about
>> this. Anyway we can use sysfs driver bind/unbind to switch drivers
>> 2) virtio device id and vendor id. I'm not sure we need this consider
>> the two drivers so far (virtio/vhost) are all bus drivers.
>>
>> Thanks
>>
>>
>>> Jason
>>>


  reply index

Thread overview: 76+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-16 12:42 [PATCH 0/5] vDPA support Jason Wang
2020-01-16 12:42 ` [PATCH 1/5] vhost: factor out IOTLB Jason Wang
2020-01-17  4:14   ` Randy Dunlap
2020-01-17  9:34     ` Jason Wang
2020-01-18  0:01   ` kbuild test robot
2020-01-18  0:40   ` kbuild test robot
2020-01-16 12:42 ` [PATCH 2/5] vringh: IOTLB support Jason Wang
2020-01-17 21:54   ` kbuild test robot
2020-01-17 22:33   ` kbuild test robot
2020-01-16 12:42 ` [PATCH 3/5] vDPA: introduce vDPA bus Jason Wang
2020-01-16 15:22   ` Jason Gunthorpe
2020-01-17  3:03     ` Jason Wang
2020-01-17 13:54       ` Jason Gunthorpe
2020-01-20  7:50         ` Jason Wang
2020-01-20 12:17         ` Michael S. Tsirkin
2020-01-20 17:50           ` Jason Gunthorpe
2020-01-20 21:56             ` Michael S. Tsirkin
2020-01-21 14:12               ` Jason Gunthorpe
2020-01-21 14:15                 ` Michael S. Tsirkin
2020-01-21 14:16                   ` Jason Gunthorpe
2020-01-21  8:40       ` Tian, Kevin
2020-01-21  9:41         ` Jason Wang [this message]
2020-01-17  4:16   ` Randy Dunlap
2020-01-17  9:34     ` Jason Wang
2020-01-17 12:13   ` Michael S. Tsirkin
2020-01-17 13:52     ` Jason Wang
     [not found]       ` <CAJPjb1+fG9L3=iKbV4Vn13VwaeDZZdcfBPvarogF_Nzhk+FnKg@mail.gmail.com>
2020-01-19  9:07         ` Shahaf Shuler
2020-01-19  9:59           ` Michael S. Tsirkin
2020-01-20  8:44             ` Jason Wang
2020-01-20 12:09               ` Michael S. Tsirkin
2020-01-21  3:32                 ` Jason Wang
2020-01-20  8:43           ` Jason Wang
2020-01-20 17:49             ` Jason Gunthorpe
2020-01-20 20:51               ` Shahaf Shuler
2020-01-20 21:25                 ` Michael S. Tsirkin
2020-01-20 21:47                   ` Shahaf Shuler
2020-01-20 21:59                     ` Michael S. Tsirkin
2020-01-21  6:01                       ` Shahaf Shuler
2020-01-21  7:57                         ` Jason Wang
2020-01-21 14:07                   ` Jason Gunthorpe
2020-01-21 14:16                     ` Michael S. Tsirkin
2020-01-20 21:48               ` Michael S. Tsirkin
2020-01-21  4:00               ` Jason Wang
2020-01-21  5:47                 ` Michael S. Tsirkin
2020-01-21  8:00                   ` Jason Wang
2020-01-21  8:15                     ` Michael S. Tsirkin
2020-01-21  8:35                       ` Jason Wang
2020-01-21 11:09                         ` Shahaf Shuler
2020-01-22  6:36                           ` Jason Wang
2020-01-21 14:05                       ` Jason Gunthorpe
2020-01-21 14:17                         ` Michael S. Tsirkin
2020-01-22  6:18                           ` Jason Wang
2020-01-20  8:19         ` Jason Wang
2020-01-16 12:42 ` [PATCH 4/5] virtio: introduce a vDPA based transport Jason Wang
2020-01-16 15:38   ` Jason Gunthorpe
2020-01-17  9:32     ` Jason Wang
2020-01-17 14:00       ` Jason Gunthorpe
2020-01-20  7:52         ` Jason Wang
2020-01-17  4:10   ` Randy Dunlap
2020-01-16 12:42 ` [PATCH 5/5] vdpasim: vDPA device simulator Jason Wang
2020-01-16 15:47   ` Jason Gunthorpe
2020-01-17  9:32     ` Jason Wang
2020-01-17 14:10       ` Jason Gunthorpe
2020-01-20  8:01         ` Jason Wang
2020-02-04  4:19         ` Jason Wang
2020-01-17  4:12   ` Randy Dunlap
2020-01-17  9:35     ` Jason Wang
2020-01-18 18:18   ` kbuild test robot
2020-01-28  3:32   ` Dan Carpenter
2020-02-04  4:07     ` Jason Wang
2020-02-04  8:21   ` Zhu Lingshan
2020-02-04  8:28     ` Jason Wang
2020-02-04 12:52       ` Jason Gunthorpe
2020-02-05  3:14         ` Jason Wang
2020-01-21  8:44 ` [PATCH 0/5] vDPA support Tian, Kevin
2020-01-21  9:39   ` Jason Wang

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