Date:   Tue, 28 Apr 2020 16:13:22 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Stefano Garzarella <sgarzare@...hat.com>, davem@...emloft.net,
        Stefan Hajnoczi <stefanha@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>
Cc:     linux-kernel@...r.kernel.org, Jorgen Hansen <jhansen@...are.com>,
        kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org,
        linux-hyperv@...r.kernel.org, Dexuan Cui <decui@...rosoft.com>,
        netdev@...r.kernel.org
Subject: Re: [PATCH net-next 0/3] vsock: support network namespace


On 2020/4/27 下午10:25, Stefano Garzarella wrote:
> Hi David, Michael, Stefan,
> I'm restarting to work on this topic since Kata guys are interested to
> have that, especially on the guest side.
>
> While working on the v2 I had few doubts, and I'd like to have your
> suggestions:
>
>   1. netns assigned to the device inside the guest
>
>     Currently I assigned this device to 'init_net'. Maybe it is better
>     if we allow the user to decide which netns assign to the device
>     or to disable this new feature to have the same behavior as before
>     (host reachable from any netns).
>     I think we can handle this in the vsock core and not in the single
>     transports.
>
>     The simplest way that I found, is to add a new
>     IOCTL_VM_SOCKETS_ASSIGN_G2H_NETNS to /dev/vsock to enable the feature
>     and assign the device to the same netns of the process that do the
>     ioctl(), but I'm not sure it is clean enough.
>
>     Maybe it is better to add new rtnetlink messages, but I'm not sure if
>     it is feasible since we don't have a netdev device.
>
>     What do you suggest?


As we've discussed, it should be a netdev probably in either guest or 
host side. And it would be much simpler if we want do implement 
namespace then. No new API is needed.

Thanks


>
>
>   2. netns assigned in the host
>
>      As Michael suggested, I added a new /dev/vhost-vsock-netns to allow
>      userspace application to use this new feature, leaving to
>      /dev/vhost-vsock the previous behavior (guest reachable from any
>      netns).
>
>      I like this approach, but I had these doubts:
>
>      - I need to allocate a new minor for that device (e.g.
>        VHOST_VSOCK_NETNS_MINOR) or is there an alternative way that I can
>        use?
>
>      - It is vhost-vsock specific, should we provide something handled in
>        the vsock core, maybe centralizing the CID allocation and adding a
>        new IOCTL or rtnetlink message like for the guest side?
>        (maybe it could be a second step, and for now we can continue with
>        the new device)
>
>
> Thanks for the help,
> Stefano
>
>
> On Thu, Jan 16, 2020 at 06:24:25PM +0100, Stefano Garzarella wrote:
>> RFC -> v1:
>>   * added 'netns' module param to vsock.ko to enable the
>>     network namespace support (disabled by default)
>>   * added 'vsock_net_eq()' to check the "net" assigned to a socket
>>     only when 'netns' support is enabled
>>
>> RFC: https://patchwork.ozlabs.org/cover/1202235/
>>
>> Now that we have multi-transport upstream, I started to take a look to
>> support network namespace in vsock.
>>
>> As we partially discussed in the multi-transport proposal [1], it could
>> be nice to support network namespace in vsock to reach the following
>> goals:
>> - isolate host applications from guest applications using the same ports
>>    with CID_ANY
>> - assign the same CID of VMs running in different network namespaces
>> - partition VMs between VMMs or at finer granularity
>>
>> This new feature is disabled by default, because it changes vsock's
>> behavior with network namespaces and could break existing applications.
>> It can be enabled with the new 'netns' module parameter of vsock.ko.
>>
>> This implementation provides the following behavior:
>> - packets received from the host (received by G2H transports) are
>>    assigned to the default netns (init_net)
>> - packets received from the guest (received by H2G - vhost-vsock) are
>>    assigned to the netns of the process that opens /dev/vhost-vsock
>>    (usually the VMM, qemu in my tests, opens the /dev/vhost-vsock)
>>      - for vmci I need some suggestions, because I don't know how to do
>>        and test the same in the vmci driver, for now vmci uses the
>>        init_net
>> - loopback packets are exchanged only in the same netns
>>
>> I tested the series in this way:
>> l0_host$ qemu-system-x86_64 -m 4G -M accel=kvm -smp 4 \
>>              -drive file=/tmp/vsockvm0.img,if=virtio --nographic \
>>              -device vhost-vsock-pci,guest-cid=3
>>
>> l1_vm$ echo 1 > /sys/module/vsock/parameters/netns
>>
>> l1_vm$ ip netns add ns1
>> l1_vm$ ip netns add ns2
>>   # same CID on different netns
>> l1_vm$ ip netns exec ns1 qemu-system-x86_64 -m 1G -M accel=kvm -smp 2 \
>>              -drive file=/tmp/vsockvm1.img,if=virtio --nographic \
>>              -device vhost-vsock-pci,guest-cid=4
>> l1_vm$ ip netns exec ns2 qemu-system-x86_64 -m 1G -M accel=kvm -smp 2 \
>>              -drive file=/tmp/vsockvm2.img,if=virtio --nographic \
>>              -device vhost-vsock-pci,guest-cid=4
>>
>>   # all iperf3 listen on CID_ANY and port 5201, but in different netns
>> l1_vm$ ./iperf3 --vsock -s # connection from l0 or guests started
>>                             # on default netns (init_net)
>> l1_vm$ ip netns exec ns1 ./iperf3 --vsock -s
>> l1_vm$ ip netns exec ns1 ./iperf3 --vsock -s
>>
>> l0_host$ ./iperf3 --vsock -c 3
>> l2_vm1$ ./iperf3 --vsock -c 2
>> l2_vm2$ ./iperf3 --vsock -c 2
>>
>> [1] https://www.spinics.net/lists/netdev/msg575792.html
>>
>> Stefano Garzarella (3):
>>    vsock: add network namespace support
>>    vsock/virtio_transport_common: handle netns of received packets
>>    vhost/vsock: use netns of process that opens the vhost-vsock device
>>
>>   drivers/vhost/vsock.c                   | 29 ++++++++++++-----
>>   include/linux/virtio_vsock.h            |  2 ++
>>   include/net/af_vsock.h                  |  7 +++--
>>   net/vmw_vsock/af_vsock.c                | 41 +++++++++++++++++++------
>>   net/vmw_vsock/hyperv_transport.c        |  5 +--
>>   net/vmw_vsock/virtio_transport.c        |  2 ++
>>   net/vmw_vsock/virtio_transport_common.c | 12 ++++++--
>>   net/vmw_vsock/vmci_transport.c          |  5 +--
>>   8 files changed, 78 insertions(+), 25 deletions(-)
>>
>> -- 
>> 2.24.1
>>

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