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Nova/pci hotplug

< Nova
Revision as of 02:24, 26 February 2014 by 苟宗梅 (talk | contribs) (Current implementation)

PCI Hotplug Support - API and Featurres

Background

In current PCI passthrough implementation, a pci device is only allowed to be assigned to a instance while the instance is being created, it is not allowed to be assigned or removed from the instance while the instance is running or stop.

Concept

1. pci_alias is configed in nova.conf on the controller node, for example,

   pci_alias={"vendor_id":"8086", "product_id":"10c9", "name":"a1"}

2. pci_passthrough_whitelist is configed in nova.conf on the compute node,for example,

   pci_passthrough_whitelist=[{ "vendor_id":"8086","product_id":"10c9"}]

Current implementation

1. Config pci_passthrough_whitelist on the compute node and pci_alias on the controller node, which means the devices you permit to be assigned to vms.
2. Create a floavor and set the "pci_passthrough:alias",for example,

   nova flavor-key gzm set "pci_passthrough:alias"="a1:2".
   
   one more request is supported too,like this,
   nova flavor-key gzm set "pci_passthrough:alias"="a1:2,b1:1".

3. Show details of the flavor, you'll see ,

   nova flavor-show gzm
   +----------------------------+--------------------------------------+
   | Property                   | Value                                |
   +----------------------------+--------------------------------------+
   | name                       | gzm                                  |
   | ram                        | 1024                                 |
   | OS-FLV-DISABLED:disabled   | False                                |
   | vcpus                      | 2                                    |
   | extra_specs                | {u'pci_passthrough:alias': u'a1:2'}  |
   | swap                       |                                      |
   | os-flavor-access:is_public | True                                 |
   | rxtx_factor                | 1.0                                  |
   | OS-FLV-EXT-DATA:ephemeral  | 0                                    |
   | disk                       | 10                                   |
   | id                         | 62686729-aa43-4fc6-99e0-b50bb84e2f60 |
   +----------------------------+--------------------------------------+

4. Create instance using the flavor above,then you'll see two pci devices have been assigned to the instance and you won't see them on the old compute node.
5. Query pci device in nova DB, you'll see,

   mysql> select * from pci_devices;
   +---------------------+---------------------+------------+---------+----+-----------------+--------------+------------+-----------+----------+------------------+-----------------+-----------+------------+--------------------------------------+
   | created_at          | updated_at          | deleted_at | deleted | id | compute_node_id | address      | product_id | vendor_id | dev_type | dev_id           | label           | status    | extra_info | instance_uuid                        |
   +---------------------+---------------------+------------+---------+----+-----------------+--------------+------------+-----------+----------+------------------+-----------------+-----------+------------+--------------------------------------+
   | 2014-02-22 06:59:16 | 2014-02-22 07:01:59 | NULL       |       0 |  1 |               1 | 0000:02:00.0 | 10c9       | 8086      | type-PCI | pci_0000_02_00_0 | label_8086_10c9 | allocated | {}         | 294c0426-693a-4514-907e-3eb17dc1de1c |
   | 2014-02-22 06:59:16 | 2014-02-22 07:01:59 | NULL       |       0 |  2 |               1 | 0000:02:00.1 | 10c9       | 8086      | type-PCI | pci_0000_02_00_1 | label_8086_10c9 | allocated | {}         | 294c0426-693a-4514-907e-3eb17dc1de1c |
   | 2014-02-22 06:59:16 | NULL                | NULL       |       0 |  3 |               1 | 0000:03:00.0 | 10c9       | 8086      | type-PCI | pci_0000_03_00_0 | label_8086_10c9 | available | {}         | NULL                                 |
   | 2014-02-22 06:59:16 | NULL                | NULL       |       0 |  4 |               1 | 0000:03:00.1 | 10c9       | 8086      | type-PCI | pci_0000_03_00_1 | label_8086_10c9 | available | {}         | NULL                                 |
   +---------------------+---------------------+------------+---------+----+-----------------+--------------+------------+-----------+----------+------------------+-----------------+-----------+------------+--------------------------------------+

The Hotplug APIs Based on Current Implementation

A proposal to allow the users to add or remove a pci device from a instance when the instance has been created.

1.Provide the api of getting the assigned pci devices from the instance, for example,

   Get  v2/​{tenant_id}​/servers/​{server_id}
   {
     ……
     "pci_devices":[
            {
             "dev_id":"pci_0000_02_00_0",
             "address":"0000:02:00.0",
             "vendor_id":"8086",
             "product_id":"10c9"
            },
           {
             "dev_id":"pci_0000_02_00_1",
             "address":"0000:02:00.1",
             "vendor_id":"8086",
             "product_id":"10c9"
            }
                 ]
   }

2. Provide the attach pci device api,for example,

   Post  v2/​{tenant_id}​/servers/​{server_id}/action
   {
       "attach_pci": 
       {
          "pci_passthrough:alias":"a1:2"     
       }
   }

3. Provide the detach pci device api,for example,

   Post  v2/​{tenant_id}​/servers/​{server_id}/action
   {
       "detach_pci": [
       {
          "dev_id":"pci_0000_02_00_0"        
       },
       {
          "dev_id":"pci_0000_02_00_1"        
       }
         ]
   }