Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755098AbbDUOGj (ORCPT ); Tue, 21 Apr 2015 10:06:39 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49779 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753360AbbDUOGh (ORCPT ); Tue, 21 Apr 2015 10:06:37 -0400 Date: Tue, 21 Apr 2015 16:06:33 +0200 From: "Michael S. Tsirkin" To: Greg Kurz Cc: Rusty Russell , Cornelia Huck , linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: Re: [PATCH v4 8/8] macvtap/tun: add VNET_BE flag Message-ID: <20150421160538-mutt-send-email-mst@redhat.com> References: <20150410101500.31843.61248.stgit@bahia.local> <20150410101923.31843.66853.stgit@bahia.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150410101923.31843.66853.stgit@bahia.local> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7408 Lines: 254 On Fri, Apr 10, 2015 at 12:20:21PM +0200, Greg Kurz wrote: > The VNET_LE flag was introduced to fix accesses to virtio 1.0 headers > that are always little-endian. It can also be used to handle the special > case of a legacy little-endian device implemented by a big-endian host. > > Let's add a flag and ioctls for big-endian devices as well. If both flags > are set, little-endian wins. > > Since this is isn't a common usecase, the feature is controlled by a kernel > config option (not set by default). > > Both macvtap and tun are covered by this patch since they share the same > API with userland. > > Signed-off-by: Greg Kurz > --- > drivers/net/Kconfig | 12 ++++++++ > drivers/net/macvtap.c | 60 +++++++++++++++++++++++++++++++++++++++++- > drivers/net/tun.c | 62 ++++++++++++++++++++++++++++++++++++++++++- > include/uapi/linux/if_tun.h | 2 + > 4 files changed, 134 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig > index df51d60..f0e23a0 100644 > --- a/drivers/net/Kconfig > +++ b/drivers/net/Kconfig > @@ -244,6 +244,18 @@ config TUN > > If you don't know what to use this for, you don't need it. > > +config TUN_VNET_BE > + bool "Support for big-endian vnet headers" > + default n > + ---help--- > + This option allows TUN/TAP and MACVTAP device drivers to parse > + vnet headers that are in big-endian byte order. It is useful > + when the headers come from a big-endian legacy virtio driver and > + the host is little-endian. > + > + Unless you have a little-endian system hosting a big-endian virtual > + machine with a virtio NIC, you should say N. > + should mention cross-endian, not big-endian, right? > config VETH > tristate "Virtual ethernet pair device" > ---help--- > diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c > index 0a03a66..e0ab1b7 100644 > --- a/drivers/net/macvtap.c > +++ b/drivers/net/macvtap.c > @@ -48,12 +48,27 @@ struct macvtap_queue { > #define MACVTAP_FEATURES (IFF_VNET_HDR | IFF_MULTI_QUEUE) > > #define MACVTAP_VNET_LE 0x80000000 > +#define MACVTAP_VNET_BE 0x40000000 > + > +#ifdef CONFIG_TUN_VNET_BE > +static inline bool macvtap_legacy_is_little_endian(struct macvtap_queue *q) > +{ > + if (q->flags & MACVTAP_VNET_BE) > + return false; > + return virtio_legacy_is_little_endian(); > +} > +#else > +static inline bool macvtap_legacy_is_little_endian(struct macvtap_queue *q) > +{ > + return virtio_legacy_is_little_endian(); > +} > +#endif > > static inline bool macvtap_is_little_endian(struct macvtap_queue *q) > { > if (q->flags & MACVTAP_VNET_LE) > return true; > - return virtio_legacy_is_little_endian(); > + return macvtap_legacy_is_little_endian(q); > } > > static inline u16 macvtap16_to_cpu(struct macvtap_queue *q, __virtio16 val) > @@ -1000,6 +1015,43 @@ static int set_offload(struct macvtap_queue *q, unsigned long arg) > return 0; > } > > +#ifdef CONFIG_TUN_VNET_BE > +static long macvtap_get_vnet_be(struct macvtap_queue *q, int __user *sp) > +{ > + int s = !!(q->flags & MACVTAP_VNET_BE); > + > + if (put_user(s, sp)) > + return -EFAULT; > + > + return 0; > +} > + > +static long macvtap_set_vnet_be(struct macvtap_queue *q, int __user *sp) > +{ > + int s; > + > + if (get_user(s, sp)) > + return -EFAULT; > + > + if (s) > + q->flags |= MACVTAP_VNET_BE; > + else > + q->flags &= ~MACVTAP_VNET_BE; > + > + return 0; > +} > +#else > +static long macvtap_get_vnet_be(struct macvtap_queue *q, int __user *argp) > +{ > + return -EINVAL; > +} > + > +static long macvtap_set_vnet_be(struct macvtap_queue *q, int __user *argp) > +{ > + return -EINVAL; > +} > +#endif /* CONFIG_TUN_VNET_BE */ > + > /* > * provide compatibility with generic tun/tap interface > */ > @@ -1097,6 +1149,12 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd, > q->flags &= ~MACVTAP_VNET_LE; > return 0; > > + case TUNGETVNETBE: > + return macvtap_get_vnet_be(q, sp); > + > + case TUNSETVNETBE: > + return macvtap_set_vnet_be(q, sp); > + > case TUNSETOFFLOAD: > /* let the user check for future flags */ > if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 | > diff --git a/drivers/net/tun.c b/drivers/net/tun.c > index 053f9b6..4e12488 100644 > --- a/drivers/net/tun.c > +++ b/drivers/net/tun.c > @@ -111,6 +111,7 @@ do { \ > #define TUN_FASYNC IFF_ATTACH_QUEUE > /* High bits in flags field are unused. */ > #define TUN_VNET_LE 0x80000000 > +#define TUN_VNET_BE 0x40000000 > > #define TUN_FEATURES (IFF_NO_PI | IFF_ONE_QUEUE | IFF_VNET_HDR | \ > IFF_MULTI_QUEUE) > @@ -206,11 +207,25 @@ struct tun_struct { > u32 flow_count; > }; > > +#ifdef CONFIG_TUN_VNET_BE > +static inline bool tun_legacy_is_little_endian(struct tun_struct *tun) > +{ > + if (tun->flags & TUN_VNET_BE) > + return false; > + return virtio_legacy_is_little_endian(); > +} > +#else > +static inline bool tun_legacy_is_little_endian(struct tun_struct *tun) > +{ > + return virtio_legacy_is_little_endian(); > +} > +#endif > + > static inline bool tun_is_little_endian(struct tun_struct *tun) > { > if (tun->flags & TUN_VNET_LE) > return true; > - return virtio_legacy_is_little_endian(); > + return tun_legacy_is_little_endian(tun); > } > > static inline u16 tun16_to_cpu(struct tun_struct *tun, __virtio16 val) > @@ -1836,6 +1851,43 @@ unlock: > return ret; > } > > +#ifdef CONFIG_TUN_VNET_BE > +static long tun_get_vnet_be(struct tun_struct *tun, int __user *argp) > +{ > + int be = !!(tun->flags & TUN_VNET_BE); > + > + if (put_user(be, argp)) > + return EFAULT; > + > + return 0; > +} > + > +static long tun_set_vnet_be(struct tun_struct *tun, int __user *argp) > +{ > + int be; > + > + if (get_user(be, argp)) > + return -EFAULT; > + > + if (be) > + tun->flags |= TUN_VNET_BE; > + else > + tun->flags &= ~TUN_VNET_BE; > + > + return 0; > +} > +#else > +static long tun_get_vnet_be(struct tun_struct *tun, int __user *argp) > +{ > + return -EINVAL; > +} > + > +static long tun_set_vnet_be(struct tun_struct *tun, int __user *argp) > +{ > + return -EINVAL; > +} > +#endif /* CONFIG_TUN_VNET_BE */ > + > static long __tun_chr_ioctl(struct file *file, unsigned int cmd, > unsigned long arg, int ifreq_len) > { > @@ -2065,6 +2117,14 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd, > tun->flags &= ~TUN_VNET_LE; > break; > > + case TUNGETVNETBE: > + ret = tun_get_vnet_be(tun, argp); > + break; > + > + case TUNSETVNETBE: > + ret = tun_set_vnet_be(tun, argp); > + break; > + > case TUNATTACHFILTER: > /* Can be set only for TAPs */ > ret = -EINVAL; > diff --git a/include/uapi/linux/if_tun.h b/include/uapi/linux/if_tun.h > index 50ae243..bcac4c0 100644 > --- a/include/uapi/linux/if_tun.h > +++ b/include/uapi/linux/if_tun.h > @@ -50,6 +50,8 @@ > #define TUNGETFILTER _IOR('T', 219, struct sock_fprog) > #define TUNSETVNETLE _IOW('T', 220, int) > #define TUNGETVNETLE _IOR('T', 221, int) > +#define TUNSETVNETBE _IOW('T', 222, int) > +#define TUNGETVNETBE _IOR('T', 223, int) > > /* TUNSETIFF ifr flags */ > #define IFF_TUN 0x0001 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/