netdev - Re: [PATCH net-next] ibmvnic: Client-initiated failover

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Message-Id: <2f2385af-023b-a5fe-9ccf-378c0340443b@linux.vnet.ibm.com>
Date:   Mon, 12 Jun 2017 14:42:54 -0500
From:   Nathan Fontenot <nfont@...ux.vnet.ibm.com>
To:     Thomas Falcon <tlfalcon@...ux.vnet.ibm.com>, netdev@...r.kernel.org
Cc:     jallen@...ux.vnet.ibm.com
Subject: Re: [PATCH net-next] ibmvnic: Client-initiated failover

On 06/12/2017 12:35 PM, Thomas Falcon wrote:
> The IBM vNIC protocol provides support for the user to initiate
> a failover from the client LPAR in case the current backing infrastructure
> is deemed inadequate or in an error state.
> 
> Support for two H_VIOCTL sub-commands for vNIC devices are required
> to implement this function. These commands are H_GET_SESSION_TOKEN
> and H_SESSION_ERR_DETECTED.
> 
> "[H_GET_SESSION_TOKEN] is used to obtain a session token from a VNIC client
> adapter.  This token is opaque to the caller and is intended to be used in
> tandem with the SESSION_ERROR_DETECTED vioctl subfunction."
> 
> "[H_SESSION_ERR_DETECTED] is used to report that the currently active
> backing device for a VNIC client adapter is behaving poorly, and that
> the hypervisor should attempt to fail over to a different backing device,
> if one is available."
> 
> To provide tools access to this functionality the vNIC driver creates a
> sysfs file that, when written to, will send a request to pHyp to failover
> to a different backing device.
> 
> Signed-off-by: Thomas Falcon <tlfalcon@...ux.vnet.ibm.com>

Reviewed-by: Nathan Fontenot <nfont@...ux.vnet.ibm.com>

> ---
>  arch/powerpc/include/asm/hvcall.h  |  2 ++
>  drivers/net/ethernet/ibm/ibmvnic.c | 46 ++++++++++++++++++++++++++++++++++++++
>  2 files changed, 48 insertions(+)
> 
> diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h
> index d73755f..57d38b5 100644
> --- a/arch/powerpc/include/asm/hvcall.h
> +++ b/arch/powerpc/include/asm/hvcall.h
> @@ -295,6 +295,8 @@
>  #define H_DISABLE_ALL_VIO_INTS	0x0A
>  #define H_DISABLE_VIO_INTERRUPT	0x0B
>  #define H_ENABLE_VIO_INTERRUPT	0x0C
> +#define H_GET_SESSION_TOKEN	0x19
> +#define H_SESSION_ERR_DETECTED	0x1A
> 
> 
>  /* Platform specific hcalls, used by KVM */
> diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
> index 7d84e20..fd3ef30 100644
> --- a/drivers/net/ethernet/ibm/ibmvnic.c
> +++ b/drivers/net/ethernet/ibm/ibmvnic.c
> @@ -3656,6 +3656,8 @@ static int ibmvnic_init(struct ibmvnic_adapter *adapter)
>  	return rc;
>  }
> 
> +static struct device_attribute dev_attr_failover;
> +
>  static int ibmvnic_probe(struct vio_dev *dev, const struct vio_device_id *id)
>  {
>  	struct ibmvnic_adapter *adapter;
> @@ -3712,9 +3714,16 @@ static int ibmvnic_probe(struct vio_dev *dev, const struct vio_device_id *id)
> 
>  	netdev->mtu = adapter->req_mtu - ETH_HLEN;
> 
> +	rc = device_create_file(&dev->dev, &dev_attr_failover);
> +	if (rc) {
> +		free_netdev(netdev);
> +		return rc;
> +	}
> +
>  	rc = register_netdev(netdev);
>  	if (rc) {
>  		dev_err(&dev->dev, "failed to register netdev rc=%d\n", rc);
> +		device_remove_file(&dev->dev, &dev_attr_failover);
>  		free_netdev(netdev);
>  		return rc;
>  	}
> @@ -3740,12 +3749,49 @@ static int ibmvnic_remove(struct vio_dev *dev)
>  	adapter->state = VNIC_REMOVED;
> 
>  	mutex_unlock(&adapter->reset_lock);
> +	device_remove_file(&dev->dev, &dev_attr_failover);
>  	free_netdev(netdev);
>  	dev_set_drvdata(&dev->dev, NULL);
> 
>  	return 0;
>  }
> 
> +static ssize_t failover_store(struct device *dev, struct device_attribute *attr,
> +			      const char *buf, size_t count)
> +{
> +	struct net_device *netdev = dev_get_drvdata(dev);
> +	struct ibmvnic_adapter *adapter = netdev_priv(netdev);
> +	unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
> +	__be64 session_token;
> +	long rc;
> +
> +	if (!sysfs_streq(buf, "1"))
> +		return -EINVAL;
> +
> +	rc = plpar_hcall(H_VIOCTL, retbuf, adapter->vdev->unit_address,
> +			 H_GET_SESSION_TOKEN, 0, 0, 0);
> +	if (rc) {
> +		netdev_err(netdev, "Couldn't retrieve session token, rc %ld\n",
> +			   rc);
> +		return -EINVAL;
> +	}
> +
> +	session_token = (__be64)retbuf[0];
> +	netdev_dbg(netdev, "Initiating client failover, session id %llx\n",
> +		   be64_to_cpu(session_token));
> +	rc = plpar_hcall_norets(H_VIOCTL, adapter->vdev->unit_address,
> +				H_SESSION_ERR_DETECTED, session_token, 0, 0);
> +	if (rc) {
> +		netdev_err(netdev, "Client initiated failover failed, rc %ld\n",
> +			   rc);
> +		return -EINVAL;
> +	}
> +
> +	return count;
> +}
> +
> +static DEVICE_ATTR(failover, 0200, NULL, failover_store);
> +
>  static unsigned long ibmvnic_get_desired_dma(struct vio_dev *vdev)
>  {
>  	struct net_device *netdev = dev_get_drvdata(&vdev->dev);
>