[pve-devel] [PATCH qemu-server 1/1] Close #2443: qemu-server: add MTU option to virtio-net device

[Thomas Lamprecht]

On 12/11/19 6:03 PM, Paul Shepel wrote:
> This patch adds support of QEMU host_mtu virtio-net parameter
> thats expose host MTU to guest
> 

Looks OK, a nit (which I can fixup locally) and a question out of interest
inline.

> Signed-off-by: Paul Shepel <tacid at tacid.kiev.ua>
> ---
>  PVE/QemuServer.pm | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
> index 865a89b..3168dde 100644
> --- a/PVE/QemuServer.pm
> +++ b/PVE/QemuServer.pm
> @@ -892,6 +892,12 @@ my $net_fmt = {
>  	description => "Rate limit in mbps (megabytes per second) as floating point number.",
>  	optional => 1,
>      },
> +    mtu => {
> +       type => 'number',
> +       minimum => 576, maximum=> 65536,

nit: space missing between maximum and =>

Do you know what the default is? Is it always 1500, or does QEMU adapt this
to the host, if the interface it's plugged to has a smaller MTU - for example.

> +       description => "MTU (virtio-net only)",
> +       optional => 1,
> +    },
>      tag => {
>  	type => 'integer',
>  	minimum => 1, maximum => 4094,
> @@ -2060,6 +2066,7 @@ sub print_netdevice_full {
>  	$tmpstr .= ",vectors=$vectors,mq=on";
>      }
>      $tmpstr .= ",bootindex=$net->{bootindex}" if $net->{bootindex} ;
> +    $tmpstr .= ",host_mtu=$net->{mtu}" if $net->{mtu} && $device eq 'virtio-net-pci';
>  
>      if ($use_old_bios_files) {
>  	my $romfile;
> @@ -5052,6 +5059,7 @@ sub vmconfig_update_net {
>  	if (&$safe_string_ne($oldnet->{model}, $newnet->{model}) ||
>  	    &$safe_string_ne($oldnet->{macaddr}, $newnet->{macaddr}) ||
>  	    &$safe_num_ne($oldnet->{queues}, $newnet->{queues}) ||
> +	    &$safe_num_ne($oldnet->{mtu}, $newnet->{mtu}) ||
>  	    !($newnet->{bridge} && $oldnet->{bridge})) { # bridge/nat mode change
>  
>              # for non online change, we try to hot-unplug
>