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From: Jason Wang <jasowang@redhat.com>
To: Parav Pandit <parav@nvidia.com>, "Michael S. Tsirkin" <mst@redhat.com>
Cc: "virtualization@lists.linux-foundation.org" 
	<virtualization@lists.linux-foundation.org>,
	Eli Cohen <elic@nvidia.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: Re: [PATCH linux-next v3 6/6] vdpa_sim_net: Add support for user supported devices
Date: Fri, 15 Jan 2021 13:38:41 +0800
Message-ID: <01213588-d4af-820a-bcf8-c28b8a80c346@redhat.com> (raw)
In-Reply-To: <BY5PR12MB43225D83EA46004E3AF50D3ADCA80@BY5PR12MB4322.namprd12.prod.outlook.com>


On 2021/1/14 下午3:58, Parav Pandit wrote:
>
>> From: Jason Wang <jasowang@redhat.com>
>> Sent: Thursday, January 14, 2021 9:48 AM
>>
>> On 2021/1/7 上午11:48, Parav Pandit wrote:
>>>> From: Michael S. Tsirkin <mst@redhat.com>
>>>> Sent: Tuesday, January 5, 2021 6:53 PM
>>>>
>>>> On Tue, Jan 05, 2021 at 12:30:15PM +0000, Parav Pandit wrote:
>>>>>> From: Michael S. Tsirkin <mst@redhat.com>
>>>>>> Sent: Tuesday, January 5, 2021 5:45 PM
>>>>>>
>>>>>> On Tue, Jan 05, 2021 at 12:02:33PM +0000, Parav Pandit wrote:
>>>>>>>> From: Michael S. Tsirkin <mst@redhat.com>
>>>>>>>> Sent: Tuesday, January 5, 2021 5:19 PM
>>>>>>>>
>>>>>>>> On Tue, Jan 05, 2021 at 12:32:03PM +0200, Parav Pandit wrote:
>>>>>>>>> Enable user to create vdpasim net simulate devices.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> $ vdpa dev add mgmtdev vdpasim_net name foo2
>>>>>>>>>
>>>>>>>>> Show the newly created vdpa device by its name:
>>>>>>>>> $ vdpa dev show foo2
>>>>>>>>> foo2: type network mgmtdev vdpasim_net vendor_id 0 max_vqs 2
>>>>>>>>> max_vq_size 256
>>>>>>>>>
>>>>>>>>> $ vdpa dev show foo2 -jp
>>>>>>>>> {
>>>>>>>>>       "dev": {
>>>>>>>>>           "foo2": {
>>>>>>>>>               "type": "network",
>>>>>>>>>               "mgmtdev": "vdpasim_net",
>>>>>>>>>               "vendor_id": 0,
>>>>>>>>>               "max_vqs": 2,
>>>>>>>>>               "max_vq_size": 256
>>>>>>>>>           }
>>>>>>>>>       }
>>>>>>>>> }
>>>>>>>> I'd like an example of how do device specific (e.g. net
>>>>>>>> specific) interfaces tie in to this.
>>>>>>> Not sure I follow your question.
>>>>>>> Do you mean how to set mac address or mtu of this vdpa device of
>>>>>>> type
>>>>>> net?
>>>>>>> If so, dev add command will be extended shortly in subsequent
>>>>>>> series to
>>>>>> set this net specific attributes.
>>>>>>> (I did mention in the next steps in cover letter).
>>>>>>>
>>>>>>>>> +static int __init vdpasim_net_init(void) {
>>>>>>>>> +	int ret;
>>>>>>>>> +
>>>>>>>>> +	if (macaddr) {
>>>>>>>>> +		mac_pton(macaddr, macaddr_buf);
>>>>>>>>> +		if (!is_valid_ether_addr(macaddr_buf))
>>>>>>>>> +			return -EADDRNOTAVAIL;
>>>>>>>>> +	} else {
>>>>>>>>> +		eth_random_addr(macaddr_buf);
>>>>>>>>>    	}
>>>>>>>> Hmm so all devices start out with the same MAC until changed?
>>>>>>>> And how is the change effected?
>>>>>>> Post this patchset and post we have iproute2 vdpa in the tree,
>>>>>>> will add the
>>>>>> mac address as the input attribute during "vdpa dev add" command.
>>>>>>> So that each different vdpa device can have user specified
>>>>>>> (different) mac
>>>>>> address.
>>>>>>
>>>>>> For now maybe just avoid VIRTIO_NET_F_MAC then for new devices
>>>> then?
>>>>> That would require book keeping existing net vdpa_sim devices
>>>>> created to
>>>> avoid setting VIRTIO_NET_F_MAC.
>>>>> Such book keeping code will be short lived anyway.
>>>>> Not sure if its worth it.
>>>>> Until now only one device was created. So not sure two vdpa devices
>>>>> with
>>>> same mac address will be a real issue.
>>>>> When we add mac address attribute in add command, at that point also
>>>> remove the module parameter macaddr.
>>>>
>>>> Will that be mandatory? I'm not to happy with a UAPI we intend to
>>>> break straight away ...
>>> No. Specifying mac address shouldn't be mandatory. UAPI wont' be
>> broken.
>>
>>
>> If it's not mandatory. Does it mean the vDPA parent need to use its own logic
>> to generate a validate mac? I'm not sure this is what management (libvirt
>> want).
>>
> There are few use cases that I see with PFs, VFs and SFs supporting vdpa devices.
>
> 1. User wants to use the VF only for vdpa purpose. Here user got the VF which was pre-setup by the sysadmin.
> In this case whatever MAC assigned to the VF can be used by its vdpa device.
> Here, user doesn't need to pass the mac address during vdpa device creation time.
> This is done as the same MAC has been setup in the ACL rules on the switch side.
> Non VDPA users of a VF typically use the VF this way for Netdev and rdma functionality.
> They might continue same way for vdpa application as well.
> Here VF mac is either set using
> (a) devlink port function set hw_addr command or using
> (b) ip link set vf mac
> So vdpa tool didn't pass the mac. (optional).
> Though VIRTIO_NET_F_MAC is still valid.
>
> 2. User may want to create one or more vdpa device out of the mgmt. device.
> Here user wants to more/full control of all features, overriding what sysadmin has setup as MAC of the VF/SF.
> In this case user will specify the MAC via mgmt tool.
> (a) This is also used by those vdpa devices which doesn't have eswitch offloads.
> (b) This will work with eswitch offloads as well who does source learning.
> (c) User chose to use the vdpa device of a VF while VF Netdev and rdma device are used by hypervisor for something else as well.
> VIRTIO_NET_F_MAC remains valid in all 2.{a,b,c}.
>
> 3. A  vendor mgmt. device always expects it user to provide mac for its vdpa devices.
> So when it is not provided, it can fail with error message string in extack or clear the VIRTIO_NET_F_MAC and let it work using virtio spec's 5.1.5 point 5 to proceed.
>
> As common denominator of all above cases, if QEMU or user pass the MAC during creation, it will almost always work.
> Advance user and QEMU with switchdev mode support who has done 1.a/1.b, will omit it.
> I do not know how deep integration of QEMU exist with the switchdev mode support.
>
> With that mac, mtu as optional input fields provide the necessary flexibility for different stacks to take appropriate shape as they desire.


Thanks for the clarification. I think we'd better document the above in 
the patch that introduces the mac setting from management API.


>


  reply index

Thread overview: 79+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-12  6:39 [PATCH 0/7] Introduce vdpa management tool Parav Pandit
2020-11-12  6:39 ` [PATCH 1/7] vdpa: Add missing comment for virtqueue count Parav Pandit
2020-11-12  6:40 ` [PATCH 2/7] vdpa: Use simpler version of ida allocation Parav Pandit
2020-11-12  6:40 ` [PATCH 3/7] vdpa: Extend routine to accept vdpa device name Parav Pandit
2020-11-12  6:40 ` [PATCH 4/7] vdpa: Define vdpa parent device, ops and a netlink interface Parav Pandit
2020-11-12  6:40 ` [PATCH 5/7] vdpa: Enable a user to add and delete a vdpa device Parav Pandit
2020-11-12  6:40 ` [PATCH 6/7] vdpa: Enable user to query vdpa device info Parav Pandit
2020-11-12  6:40 ` [PATCH 7/7] vdpa/vdpa_sim: Enable user to create vdpasim net devices Parav Pandit
2020-11-16  9:41 ` [PATCH 0/7] Introduce vdpa management tool Stefan Hajnoczi
2020-11-17 19:41   ` Parav Pandit
2020-11-16 22:23 ` Jakub Kicinski
2020-11-17 19:51   ` Parav Pandit
2020-12-16  9:13     ` Michael S. Tsirkin
     [not found]       ` <20201216080610.08541f44@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
2020-12-16 16:54         ` Parav Pandit
2020-12-16 19:57           ` Michael S. Tsirkin
2020-12-17 12:13             ` Parav Pandit
2020-11-27  3:53 ` Jason Wang
     [not found]   ` <CACycT3sYScObb9nN3g7L3cesjE7sCZWxZ5_5R1usGU9ePZEeqA@mail.gmail.com>
2020-11-30  3:36     ` [External] " Jason Wang
2020-11-30  7:07       ` Yongji Xie
2020-12-01  6:25         ` Jason Wang
2020-12-01  9:55           ` Yongji Xie
2020-12-01 11:32             ` Parav Pandit
2020-12-01 14:18               ` Yongji Xie
2020-12-01 15:58                 ` Parav Pandit
2020-12-02  3:29                   ` Yongji Xie
2020-12-02  4:53                     ` Parav Pandit
2020-12-02  5:51                       ` Jason Wang
2020-12-02  6:24                         ` Parav Pandit
2020-12-02  7:55                           ` Jason Wang
2020-12-02  9:27                         ` Yongji Xie
2020-12-02  9:21                       ` Yongji Xie
2020-12-02 11:13                         ` Parav Pandit
2020-12-02 13:18                           ` Yongji Xie
2020-12-02  5:48             ` Jason Wang
2020-12-08 22:47   ` David Ahern
2021-01-19  4:21     ` Parav Pandit
2020-12-16  9:16 ` Michael S. Tsirkin
2021-01-04  3:31 ` [PATCH linux-next v2 " Parav Pandit
2021-01-04  3:31   ` [PATCH linux-next v2 1/7] vdpa_sim_net: Make mac address array static Parav Pandit
2021-01-04  7:00     ` Jason Wang
2021-01-04  3:31   ` [PATCH linux-next v2 2/7] vdpa_sim_net: Add module param to disable default vdpa net device Parav Pandit
2021-01-04  3:31   ` [PATCH linux-next v2 3/7] vdpa: Extend routine to accept vdpa device name Parav Pandit
2021-01-04  3:31   ` [PATCH linux-next v2 4/7] vdpa: Define vdpa mgmt device, ops and a netlink interface Parav Pandit
2021-01-04  7:03     ` Jason Wang
2021-01-04  7:24       ` Parav Pandit
2021-01-05  4:10         ` Jason Wang
2021-01-05  6:33           ` Parav Pandit
2021-01-05  8:36             ` Jason Wang
2021-01-04  3:31   ` [PATCH linux-next v2 5/7] vdpa: Enable a user to add and delete a vdpa device Parav Pandit
2021-01-04  3:31   ` [PATCH linux-next v2 6/7] vdpa: Enable user to query vdpa device info Parav Pandit
2021-01-04  3:31   ` [PATCH linux-next v2 7/7] vdpa_sim_net: Add support for user supported devices Parav Pandit
2021-01-04  7:05     ` Jason Wang
2021-01-04  7:21       ` Parav Pandit
2021-01-05  4:06         ` Jason Wang
2021-01-05  6:22           ` Parav Pandit
2021-01-05 10:31 ` [PATCH linux-next v3 0/6] Introduce vdpa management tool Parav Pandit
2021-01-05 10:31   ` [PATCH linux-next v3 1/6] vdpa_sim_net: Make mac address array static Parav Pandit
2021-01-07 13:45     ` Stefano Garzarella
2021-01-05 10:31   ` [PATCH linux-next v3 2/6] vdpa: Extend routine to accept vdpa device name Parav Pandit
2021-01-05 10:32   ` [PATCH linux-next v3 3/6] vdpa: Define vdpa mgmt device, ops and a netlink interface Parav Pandit
2021-01-05 10:32   ` [PATCH linux-next v3 4/6] vdpa: Enable a user to add and delete a vdpa device Parav Pandit
2021-01-05 10:32   ` [PATCH linux-next v3 5/6] vdpa: Enable user to query vdpa device info Parav Pandit
2021-01-05 10:32   ` [PATCH linux-next v3 6/6] vdpa_sim_net: Add support for user supported devices Parav Pandit
2021-01-05 11:48     ` Michael S. Tsirkin
2021-01-05 12:02       ` Parav Pandit
2021-01-05 12:14         ` Michael S. Tsirkin
2021-01-05 12:30           ` Parav Pandit
2021-01-05 13:23             ` Michael S. Tsirkin
2021-01-07  3:48               ` Parav Pandit
2021-01-12  4:14                 ` Parav Pandit
2021-01-14  4:17                 ` Jason Wang
2021-01-14  7:58                   ` Parav Pandit
2021-01-15  5:38                     ` Jason Wang [this message]
2021-01-15  6:27                       ` Parav Pandit
2021-01-19 11:09                         ` Jason Wang
2021-01-20  3:21                           ` Parav Pandit
2021-01-20  3:46                             ` Parav Pandit
2021-01-18 18:03                       ` Parav Pandit
2021-01-20  7:53                         ` Michael S. Tsirkin

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