Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752658AbaJWJLz (ORCPT ); Thu, 23 Oct 2014 05:11:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:11057 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751552AbaJWJLv (ORCPT ); Thu, 23 Oct 2014 05:11:51 -0400 Date: Thu, 23 Oct 2014 12:15:02 +0300 From: "Michael S. Tsirkin" To: Cornelia Huck Cc: linux-kernel@vger.kernel.org, Bjarke Istrup Pedersen , Anup Patel , Greg Kroah-Hartman , virtualization@lists.linux-foundation.org, Geert Uytterhoeven , Sakari Ailus , linux-api@vger.kernel.org, "David S. Miller" , Piotr =?iso-8859-1?Q?Kr=F3l?= , Alexei Starovoitov Subject: Re: [PATCH RFC v3 01/16] virtio: memory access APIs Message-ID: <20141023091502.GA7028@redhat.com> References: <1414003404-505-1-git-send-email-mst@redhat.com> <1414003404-505-2-git-send-email-mst@redhat.com> <20141023095405.6bdd5a1a.cornelia.huck@de.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141023095405.6bdd5a1a.cornelia.huck@de.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 23, 2014 at 09:54:05AM +0200, Cornelia Huck wrote: > On Wed, 22 Oct 2014 21:44:08 +0300 > "Michael S. Tsirkin" wrote: > > > virtio 1.0 makes all memory structures LE, so > > we need APIs to conditionally do a byteswap on BE > > architectures. > > > > To make it easier to check code statically, > > add virtio specific types for multi-byte integers > > in memory. > > > > Add low level wrappers that do a byteswap conditionally, these will be > > useful e.g. for vhost. Add high level wrappers that will (in the > > future) query device endian-ness and act accordingly. > > > > At the moment, stub them out and assume native endian-ness everywhere. > > > > Signed-off-by: Michael S. Tsirkin > > --- > > include/linux/virtio_byteorder.h | 29 ++++++++++++++++++++++++ > > include/linux/virtio_config.h | 16 +++++++++++++ > > include/uapi/linux/virtio_ring.h | 49 ++++++++++++++++++++-------------------- > > include/uapi/linux/Kbuild | 1 + > > 4 files changed, 71 insertions(+), 24 deletions(-) > > create mode 100644 include/linux/virtio_byteorder.h > > > > diff --git a/include/linux/virtio_byteorder.h b/include/linux/virtio_byteorder.h > > new file mode 100644 > > index 0000000..7afdd8a > > --- /dev/null > > +++ b/include/linux/virtio_byteorder.h > > @@ -0,0 +1,29 @@ > > +#ifndef _LINUX_VIRTIO_BYTEORDER_H > > +#define _LINUX_VIRTIO_BYTEORDER_H > > +#include > > +#include > > + > > +/* Memory accessors for handling virtio in modern little endian and in > > + * compatibility big endian format. */ > > s/big/native/ Thanks. > > + > > +#define __DEFINE_VIRTIO_XX_TO_CPU(bits) \ > > +static inline u##bits __virtio##bits##_to_cpu(bool little_endian, __virtio##bits val) \ > > +{ \ > > + if (little_endian) \ > > + return le##bits##_to_cpu((__force __le##bits)val); \ > > + else \ > > + return (__force u##bits)val; \ > > +} \ > > +static inline __virtio##bits __cpu_to_virtio##bits(bool little_endian, u##bits val) \ > > +{ \ > > + if (little_endian) \ > > + return (__force __virtio##bits)cpu_to_le##bits(val); \ > > + else \ > > + return val; \ > > +} > > + > > +__DEFINE_VIRTIO_XX_TO_CPU(16) > > +__DEFINE_VIRTIO_XX_TO_CPU(32) > > +__DEFINE_VIRTIO_XX_TO_CPU(64) > > ...although I'm still not too happy with macro-generated helpers. I'm fine with open-coding them. > > + > > +#endif /* _LINUX_VIRTIO_BYTEORDER */ > > > diff --git a/include/uapi/linux/virtio_ring.h b/include/uapi/linux/virtio_ring.h > > index a99f9b7..6c00632 100644 > > --- a/include/uapi/linux/virtio_ring.h > > +++ b/include/uapi/linux/virtio_ring.h > > > @@ -61,32 +62,32 @@ > > /* Virtio ring descriptors: 16 bytes. These can chain together via "next". */ > > struct vring_desc { > > /* Address (guest-physical). */ > > - __u64 addr; > > + __virtio64 addr; > > /* Length. */ > > - __u32 len; > > + __virtio32 len; > > /* The flags as indicated above. */ > > - __u16 flags; > > + __virtio16 flags; > > /* We chain unused descriptors via this, too */ > > - __u16 next; > > + __virtio16 next; > > }; > > I think all of these __virtio types need an explanation somewhere as to > what they mean, e.g.: > > /* > * __virtio{16,32,64} have the following meaning: > * - __u{16,32,64} for virtio devices in legacy mode, > * accessed in native endian > * - __le{16,32,64} for standard-compliant virtio devices > */ Will do. -- MST -- 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/