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Re: [PATCH v2 0/1] virtio: failover: allow to keep the VFIO device rathe
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From: |
Jason Wang |
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Subject: |
Re: [PATCH v2 0/1] virtio: failover: allow to keep the VFIO device rather than the virtio-net one |
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Date: |
Wed, 11 Aug 2021 12:17:25 +0800 |
On Tue, Aug 10, 2021 at 1:13 AM Laurent Vivier <lvivier@redhat.com> wrote:
>
> v2: use validate_features() to disable the guest driver rather
> than setting vring.num to 0.
>
> With failover, when the guest virtio-net driver doesn't support the
> STANDBY feature, the primary device is not plugged and only the virtio-net
> device is kept. Doing like that we can migrate the machine and
> keep the network connection.
>
> But in some cases, when performance is more important than availability
> we would prefer to keep the VFIO device rather than the virtio-net one,
> even if it means to lose the network connection during the migration of
> the machine.
I think we still need to seek a way to recover the network after migration.
Thanks
>
> To do that we can't simply unplug the virtio-net device and plug the
> VFIO one because for the migration the initial state must be kept
> (virtio-net plugged, VFIO unplugged) but we can try to disable the
> virtio-net driver and plug the VFIO card, so the initial state is
> correct (the virtio-net card is plugged, but disabled in guest, and
> the VFIO card is unplugged before migration).
>
> This change doesn't impact the case when guest and host support
> the STANDBY feature.
>
> I've introduced the "failover-default" property to virtio-net device
> to set which device to keep (failover-default=true keeps the virtio-net
> device, =off the other one).
>
> For example, with a guest driver that doesn't support STANDBY:
>
> ...
> -device virtio-net-pci,id=virtio0,failover=on,failover-default=on \
> -device vfio-pci,host=$PCI,id=hostdev0,failover_pair_id=virtio0 \
> ...
>
> [root@localhost ~]# ip a
> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
> link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
> inet 127.0.0.1/8 scope host lo
> valid_lft forever preferred_lft forever
> inet6 ::1/128 scope host
> valid_lft forever preferred_lft forever
> 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state
> UP q0
> link/ether 26:28:c5:7f:14:24 brd ff:ff:ff:ff:ff:ff
> inet 192.168.20.2/24 brd 192.168.20.255 scope global eth0
> valid_lft forever preferred_lft forever
> inet6 fe80::2428:c5ff:fe7f:1424/64 scope link
> valid_lft forever preferred_lft forever
> # ethtool -i eth0
> driver: virtio_net
> version: 1.0.0
> firmware-version:
> expansion-rom-version:
> bus-info: 0000:04:00.0
> supports-statistics: no
> supports-test: no
> supports-eeprom-access: no
> supports-register-dump: no
> supports-priv-flags: no
>
> ...
> -device virtio-net-pci,id=virtio0,failover=on,failover-default=off \
> -device vfio-pci,host=$PCI,id=hostdev0,failover_pair_id=virtio0 \
> ...
>
> [root@localhost ~]# ip a
> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
> link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
> inet 127.0.0.1/8 scope host lo
> valid_lft forever preferred_lft forever
> inet6 ::1/128 scope host
> valid_lft forever preferred_lft forever
> 2: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP
> qlen 100
> link/ether 26:28:c5:7f:14:24 brd ff:ff:ff:ff:ff:ff
> inet 192.168.20.2/24 brd 192.168.20.255 scope global enp2s0
> valid_lft forever preferred_lft forever
> inet6 fe80::2428:c5ff:fe7f:1424/64 scope link
> valid_lft forever preferred_lft forever
> [root@localhost ~]# ethtool -i enp2s0
> driver: i40evf
> version: 1.6.27-k
> firmware-version: N/A
> expansion-rom-version:
> bus-info: 0000:02:00.0
> supports-statistics: yes
> supports-test: no
> supports-eeprom-access: no
> supports-register-dump: no
> supports-priv-flags: no
>
> With guest driver that supports STANDBY, we would always have:
>
> [root@localhost ~]# ip a
> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group
> defau0
> link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
> inet 127.0.0.1/8 scope host lo
> valid_lft forever preferred_lft forever
> inet6 ::1/128 scope host
> valid_lft forever preferred_lft forever
> 2: enp4s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state
> UP gr0
> link/ether 26:28:c5:7f:14:24 brd ff:ff:ff:ff:ff:ff
> inet 192.168.20.2/24 brd 192.168.20.255 scope global noprefixroute
> enp4s0
> valid_lft forever preferred_lft forever
> inet6 fe80::2428:c5ff:fe7f:1424/64 scope link
> valid_lft forever preferred_lft forever
> 3: enp4s0nsby: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel
> master0
> link/ether 26:28:c5:7f:14:24 brd ff:ff:ff:ff:ff:ff
> 4: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq master
> enp4s0 st0
> link/ether 26:28:c5:7f:14:24 brd ff:ff:ff:ff:ff:ff
> [root@localhost ~]# ethtool -i enp4s0
> driver: net_failover
> version: 0.1
> firmware-version:
> expansion-rom-version:
> bus-info:
> supports-statistics: no
> supports-test: no
> supports-eeprom-access: no
> supports-register-dump: no
> supports-priv-flags: no
> [root@localhost ~]# ethtool -i enp4s0nsby
> driver: virtio_net
> version: 1.0.0
> firmware-version:
> expansion-rom-version:
> bus-info: 0000:04:00.0
> supports-statistics: yes
> supports-test: no
> supports-eeprom-access: no
> supports-register-dump: no
> supports-priv-flags: no
> [root@localhost ~]# ethtool -i enp2s0
> driver: iavf
> version: 4.18.0-310.el8.x86_64
> firmware-version: N/A
> expansion-rom-version:
> bus-info: 0000:02:00.0
> supports-statistics: yes
> supports-test: no
> supports-eeprom-access: no
> supports-register-dump: no
> supports-priv-flags: yes
>
> Laurent Vivier (1):
> virtio: failover: define the default device to use in case of error
>
> include/hw/virtio/virtio-net.h | 1 +
> hw/net/virtio-net.c | 49 +++++++++++++++++++++++++++++-----
> 2 files changed, 44 insertions(+), 6 deletions(-)
>
> --
> 2.31.1
>
>