Subject: Re: [PATCH] hyperv: Add netpoll support

From: Richard Weinberger <[email-masked]>
Date: Tue, 08 Jul 2014 20:39:01 +0200

Am 08.07.2014 20:01, schrieb KY Srinivasan:
> 
> 
>> -----Original Message-----
>> From: Richard Weinberger [mailto:[email-masked]]
>> Sent: Tuesday, July 8, 2014 2:32 AM
>> To: KY Srinivasan; Haiyang Zhang
>> Cc: [email-masked]; [email-masked]; linux-
>> [email-masked]; Richard Weinberger
>> Subject: [PATCH] hyperv: Add netpoll support
>>
>> In order to have at least a netconsole to debug kernel issues on Windows
>> Azure this patch implements netpoll support.
>> Sending packets is easy, netvsc_start_xmit() does already everything
>> needed.
>> To receive we need to trigger the channel callback which is usally called via
>> tasklet_schedule().
>>
>> Signed-off-by: Richard Weinberger <[email-masked]>
>> ---
>>  drivers/net/hyperv/netvsc_drv.c | 14 ++++++++++++++
>>  1 file changed, 14 insertions(+)
>>
>> diff --git a/drivers/net/hyperv/netvsc_drv.c
>> b/drivers/net/hyperv/netvsc_drv.c index 4fd71b7..367b71e 100644
>> --- a/drivers/net/hyperv/netvsc_drv.c
>> +++ b/drivers/net/hyperv/netvsc_drv.c
>> @@ -736,6 +736,17 @@ static int netvsc_set_mac_addr(struct net_device
>> *ndev, void *p)
>>  	return err;
>>  }
>>
>> +#ifdef CONFIG_NET_POLL_CONTROLLER
>> +static void netvsc_poll_controller(struct net_device *net) {
>> +	struct net_device_context *net_device_ctx = netdev_priv(net);
>> +	struct hv_device *dev = net_device_ctx->device_ctx;
>> +
>> +	local_bh_disable();
>> +	netvsc_channel_cb(dev->channel);
>> +	local_bh_enable();
>> +}
>> +#endif
> 
> Each channel is bound to a specific VCPU in the guest and the channel callback is expected to be delivered on
> the VCPU the channel is bound to. This code is not satisfying that requirement.

But struct hv_device has only one channel attribute. How does this work with multiple VCPUs?

Anyways, what solution to you propose?

Thanks,
//richard