Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933766AbbDUQXt (ORCPT ); Tue, 21 Apr 2015 12:23:49 -0400 Received: from e06smtp17.uk.ibm.com ([195.75.94.113]:46906 "EHLO e06smtp17.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932740AbbDUQXd (ORCPT ); Tue, 21 Apr 2015 12:23:33 -0400 Date: Tue, 21 Apr 2015 18:23:25 +0200 From: Greg Kurz To: "Michael S. Tsirkin" 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 6/8] virtio: add explicit big-endian support to memory accessors Message-ID: <20150421182325.551a90b0@bahia.local> In-Reply-To: <20150421160652-mutt-send-email-mst@redhat.com> References: <20150410101500.31843.61248.stgit@bahia.local> <20150410101616.31843.51000.stgit@bahia.local> <20150421160652-mutt-send-email-mst@redhat.com> Organization: IBM X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.27; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15042116-0029-0000-0000-0000044C0F3C Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7274 Lines: 208 On Tue, 21 Apr 2015 16:09:44 +0200 "Michael S. Tsirkin" wrote: > On Fri, Apr 10, 2015 at 12:16:20PM +0200, Greg Kurz wrote: > > The current memory accessors logic is: > > - little endian if little_endian > > - native endian (i.e. no byteswap) if !little_endian > > > > If we want to fully support cross-endian vhost, we also need to be > > able to convert to big endian. > > > > Instead of changing the little_endian argument to some 3-value enum, this > > patch changes the logic to: > > - little endian if little_endian > > - big endian if !little_endian > > > > The native endian case is handled by all users with a trivial helper. This > > patch doesn't change any functionality, nor it does add overhead. > > > > Signed-off-by: Greg Kurz > > --- > > OK overall. Style comment: > > > drivers/net/macvtap.c | 4 +++- > > drivers/net/tun.c | 4 +++- > > drivers/vhost/vhost.h | 4 +++- > > include/linux/virtio_byteorder.h | 24 ++++++++++++++---------- > > include/linux/virtio_config.h | 4 +++- > > include/linux/vringh.h | 4 +++- > > 6 files changed, 29 insertions(+), 15 deletions(-) > > > > diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c > > index a2f2958..0a03a66 100644 > > --- a/drivers/net/macvtap.c > > +++ b/drivers/net/macvtap.c > > @@ -51,7 +51,9 @@ struct macvtap_queue { > > > > static inline bool macvtap_is_little_endian(struct macvtap_queue *q) > > { > > - return q->flags & MACVTAP_VNET_LE; > > + if (q->flags & MACVTAP_VNET_LE) > > + return true; > > + return virtio_legacy_is_little_endian(); > > } > > > > I'd prefer a bit more symmetry: > > + if (q->flags & MACVTAP_VNET_LE) > + return true; > + else > + return virtio_legacy_is_little_endian(); > > Or better just: > return (q->flags & MACVTAP_VNET_LE) ? true : virtio_legacy_is_little_endian(); > > might make line long, but your follow-up patch makes it short again, > so that's ok. > Will do. > > > static inline u16 macvtap16_to_cpu(struct macvtap_queue *q, __virtio16 val) > > diff --git a/drivers/net/tun.c b/drivers/net/tun.c > > index 3c3d6c0..053f9b6 100644 > > --- a/drivers/net/tun.c > > +++ b/drivers/net/tun.c > > @@ -208,7 +208,9 @@ struct tun_struct { > > > > static inline bool tun_is_little_endian(struct tun_struct *tun) > > { > > - return tun->flags & TUN_VNET_LE; > > + if (tun->flags & TUN_VNET_LE) > > + return true; > > + return virtio_legacy_is_little_endian(); > > } > > > > static inline u16 tun16_to_cpu(struct tun_struct *tun, __virtio16 val) > > diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h > > index 6a49960..4e9a186 100644 > > --- a/drivers/vhost/vhost.h > > +++ b/drivers/vhost/vhost.h > > @@ -175,7 +175,9 @@ static inline bool vhost_has_feature(struct vhost_virtqueue *vq, int bit) > > > > static inline bool vhost_is_little_endian(struct vhost_virtqueue *vq) > > { > > - return vhost_has_feature(vq, VIRTIO_F_VERSION_1); > > + if (vhost_has_feature(vq, VIRTIO_F_VERSION_1)) > > + return true; > > + return virtio_legacy_is_little_endian(); > > } > > > > /* Memory accessors */ > > diff --git a/include/linux/virtio_byteorder.h b/include/linux/virtio_byteorder.h > > index 51865d0..ce63a2c 100644 > > --- a/include/linux/virtio_byteorder.h > > +++ b/include/linux/virtio_byteorder.h > > @@ -3,17 +3,21 @@ > > #include > > #include > > > > -/* > > - * Low-level memory accessors for handling virtio in modern little endian and in > > - * compatibility native endian format. > > - */ > > +static inline bool virtio_legacy_is_little_endian(void) > > +{ > > +#ifdef __LITTLE_ENDIAN > > + return true; > > +#else > > + return false; > > +#endif > > +} > > > > static inline u16 __virtio16_to_cpu(bool little_endian, __virtio16 val) > > { > > if (little_endian) > > return le16_to_cpu((__force __le16)val); > > else > > - return (__force u16)val; > > + return be16_to_cpu((__force __be16)val); > > } > > > > static inline __virtio16 __cpu_to_virtio16(bool little_endian, u16 val) > > @@ -21,7 +25,7 @@ static inline __virtio16 __cpu_to_virtio16(bool little_endian, u16 val) > > if (little_endian) > > return (__force __virtio16)cpu_to_le16(val); > > else > > - return (__force __virtio16)val; > > + return (__force __virtio16)cpu_to_be16(val); > > } > > > > static inline u32 __virtio32_to_cpu(bool little_endian, __virtio32 val) > > @@ -29,7 +33,7 @@ static inline u32 __virtio32_to_cpu(bool little_endian, __virtio32 val) > > if (little_endian) > > return le32_to_cpu((__force __le32)val); > > else > > - return (__force u32)val; > > + return be32_to_cpu((__force __be32)val); > > } > > > > static inline __virtio32 __cpu_to_virtio32(bool little_endian, u32 val) > > @@ -37,7 +41,7 @@ static inline __virtio32 __cpu_to_virtio32(bool little_endian, u32 val) > > if (little_endian) > > return (__force __virtio32)cpu_to_le32(val); > > else > > - return (__force __virtio32)val; > > + return (__force __virtio32)cpu_to_be32(val); > > } > > > > static inline u64 __virtio64_to_cpu(bool little_endian, __virtio64 val) > > @@ -45,7 +49,7 @@ static inline u64 __virtio64_to_cpu(bool little_endian, __virtio64 val) > > if (little_endian) > > return le64_to_cpu((__force __le64)val); > > else > > - return (__force u64)val; > > + return be64_to_cpu((__force __be64)val); > > } > > > > static inline __virtio64 __cpu_to_virtio64(bool little_endian, u64 val) > > @@ -53,7 +57,7 @@ static inline __virtio64 __cpu_to_virtio64(bool little_endian, u64 val) > > if (little_endian) > > return (__force __virtio64)cpu_to_le64(val); > > else > > - return (__force __virtio64)val; > > + return (__force __virtio64)cpu_to_be64(val); > > } > > > > #endif /* _LINUX_VIRTIO_BYTEORDER */ > > diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h > > index bd1a582..36a6daa 100644 > > --- a/include/linux/virtio_config.h > > +++ b/include/linux/virtio_config.h > > @@ -207,7 +207,9 @@ int virtqueue_set_affinity(struct virtqueue *vq, int cpu) > > > > static inline bool virtio_is_little_endian(struct virtio_device *vdev) > > { > > - return virtio_has_feature(vdev, VIRTIO_F_VERSION_1); > > + if (virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) > > + return true; > > + return virtio_legacy_is_little_endian(); > > } > > > > /* Memory accessors */ > > diff --git a/include/linux/vringh.h b/include/linux/vringh.h > > index 3ed62ef..d786c2d 100644 > > --- a/include/linux/vringh.h > > +++ b/include/linux/vringh.h > > @@ -228,7 +228,9 @@ static inline void vringh_notify(struct vringh *vrh) > > > > static inline bool vringh_is_little_endian(const struct vringh *vrh) > > { > > - return vrh->little_endian; > > + if (vrh->little_endian) > > + return true; > > + return virtio_legacy_is_little_endian(); > > } > > > > static inline u16 vringh16_to_cpu(const struct vringh *vrh, __virtio16 val) > -- 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/