Re: [dpdk-dev] [PATCH v2] vhost: add interface name to virtio-net struct

["Xie, Huawei" <huawei.xie@intel.com>]

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Linhaifeng
> Sent: Sunday, January 25, 2015 12:42 PM
> To: Loftus, Ciara; dev@dpdk.org
> Cc: Anthony Fee
> Subject: Re: [dpdk-dev] [PATCH v2] vhost: add interface name to virtio-net struct
> 
> 
> 
> On 2014/12/19 2:07, ciara.loftus@intel.com wrote:
> > From: Ciara Loftus <ciara.loftus@intel.com>
> >
> > This patch fixes the issue whereby when using userspace vhost ports
> > in the context of vSwitching, the name provided to the hypervisor/QEMU
> > of the vhost tap device needs to be exposed in the library, in order
> 
> Who create the tap device?When using vhost-user QEMU will not create it.
> 
> > for the vSwitch to be able to direct packets to the correct device.
> 
> Why not use unix domain socket path?

In this patch, for vhost-cuse, the ifname comes from the name of the tap device.
For vhost-user, ifname is the name of the socket path.

> 
> > This patch introduces an 'ifname' member to the virtio-net structure
> > which is populated with the tap device name when QEMU is brought up
> > with a vhost device.
> >
> > Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
> > Signed-off-by: Anthony Fee <anthonyx.fee@intel.com>
> > Acked-by: Huawei Xie <huawei.xie@intel.com>
> > ---
> >  lib/librte_vhost/rte_virtio_net.h |    3 ++
> >  lib/librte_vhost/virtio-net.c     |   48
> ++++++++++++++++++++++++++++++++++++-
> >  2 files changed, 50 insertions(+), 1 deletions(-)
> >
> > diff --git a/lib/librte_vhost/rte_virtio_net.h b/lib/librte_vhost/rte_virtio_net.h
> > index 00b1328..0bf07c7 100644
> > --- a/lib/librte_vhost/rte_virtio_net.h
> > +++ b/lib/librte_vhost/rte_virtio_net.h
> > @@ -43,6 +43,8 @@
> >  #include <linux/virtio_ring.h>
> >  #include <linux/virtio_net.h>
> >  #include <sys/eventfd.h>
> > +#include <sys/socket.h>
> > +#include <linux/if.h>
> >
> >  #include <rte_memory.h>
> >  #include <rte_mempool.h>
> > @@ -96,6 +98,7 @@ struct virtio_net {
> >  	uint64_t		features;	/**< Negotiated feature set.
> */
> >  	uint64_t		device_fh;	/**< device identifier. */
> >  	uint32_t		flags;		/**< Device flags. Only used to
> check if device is running on data core. */
> > +	char			ifname[IFNAMSIZ];	/**< Name of the tap
> device. */
> >  	void			*priv;		/**< private context */
> >  } __rte_cache_aligned;
> >
> > diff --git a/lib/librte_vhost/virtio-net.c b/lib/librte_vhost/virtio-net.c
> > index 852b6d1..7eae5ee 100644
> > --- a/lib/librte_vhost/virtio-net.c
> > +++ b/lib/librte_vhost/virtio-net.c
> > @@ -43,6 +43,10 @@
> >  #include <sys/mman.h>
> >  #include <unistd.h>
> >
> > +#include <sys/socket.h>
> > +#include <linux/if_tun.h>
> > +#include <linux/if.h>
> > +
> >  #include <rte_ethdev.h>
> >  #include <rte_log.h>
> >  #include <rte_string_fns.h>
> > @@ -1000,6 +1004,46 @@ set_vring_kick(struct vhost_device_ctx ctx, struct
> vhost_vring_file *file)
> >  }
> >
> >  /*
> > + * Function to get the tap device name from the provided file descriptor and
> > + * save it in the device structure.
> > + */
> > +static int
> > +get_ifname(struct virtio_net *dev, int tap_fd, int pid)
> > +{
> > +	struct eventfd_copy fd_tap;
> > +	struct ifreq ifr;
> > +	uint32_t size, ifr_size;
> > +	int ret;
> > +
> > +	fd_tap.source_fd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
> > +	fd_tap.target_fd = tap_fd;
> > +	fd_tap.target_pid = pid;
> > +
> > +	if (eventfd_copy(dev, &fd_tap))
> > +		return -1;
> > +
> > +	ret = ioctl(fd_tap.source_fd, TUNGETIFF, &ifr);
> > +
> > +	if (close(fd_tap.source_fd) < 0)
> > +		RTE_LOG(ERR, VHOST_CONFIG,
> > +			"(%"PRIu64") fd close failed\n",
> > +			dev->device_fh);
> > +
> > +	if (ret >= 0) {
> > +		ifr_size = strnlen(ifr.ifr_name, sizeof(ifr.ifr_name));
> > +		size = ifr_size > sizeof(dev->ifname)?
> > +				sizeof(dev->ifname): ifr_size;
> > +
> > +		strncpy(dev->ifname, ifr.ifr_name, size);
> > +	} else
> > +		RTE_LOG(ERR, VHOST_CONFIG,
> > +			"(%"PRIu64") TUNGETIFF ioctl failed\n",
> > +			dev->device_fh);
> > +
> > +	return 0;
> > +}
> > +
> > +/*
> >   * Called from CUSE IOCTL: VHOST_NET_SET_BACKEND
> >   * To complete device initialisation when the virtio driver is loaded,
> >   * we are provided with a valid fd for a tap device (not used by us).
> > @@ -1026,8 +1070,10 @@ set_backend(struct vhost_device_ctx ctx, struct
> vhost_vring_file *file)
> >  	 */
> >  	if (!(dev->flags & VIRTIO_DEV_RUNNING)) {
> >  		if (((int)dev->virtqueue[VIRTIO_TXQ]->backend !=
> VIRTIO_DEV_STOPPED) &&
> > -			((int)dev->virtqueue[VIRTIO_RXQ]->backend !=
> VIRTIO_DEV_STOPPED))
> > +			((int)dev->virtqueue[VIRTIO_RXQ]->backend !=
> VIRTIO_DEV_STOPPED)) {
> > +			get_ifname(dev, file->fd, ctx.pid);
> >  			return notify_ops->new_device(dev);
> > +		}
> >  	/* Otherwise we remove it. */
> >  	} else
> >  		if (file->fd == VIRTIO_DEV_STOPPED)
> >
> 
> --
> Regards,
> Haifeng