From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH RFC v2 01/16] virtio: memory access APIs Date: Wed, 22 Oct 2014 21:40:14 +0300 Message-ID: <20141022184014.GA10919@redhat.com> References: <1413992894-22976-1-git-send-email-mst@redhat.com> <1413992894-22976-2-git-send-email-mst@redhat.com> <5447ED53.2030502@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <5447ED53.2030502@codeaurora.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Christopher Covington Cc: Bjarke Istrup Pedersen , Anup Patel , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, David Drysdale , "Lad, Prabhakar" , Geert Uytterhoeven , linux-api@vger.kernel.org, Alexei Starovoitov , virtualization@lists.linux-foundation.org, "David S. Miller" , Piotr =?iso-8859-1?Q?Kr=F3l?= , Mauro Carvalho Chehab List-Id: linux-api@vger.kernel.org On Wed, Oct 22, 2014 at 01:45:55PM -0400, Christopher Covington wrote: > Hi Michael, > > On 10/22/2014 11:50 AM, 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_config.h | 16 +++++++++++++ > > include/uapi/linux/virtio_ring.h | 49 ++++++++++++++++++++-------------------- > > include/uapi/linux/Kbuild | 1 + > > 3 files changed, 42 insertions(+), 24 deletions(-) > > > > diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h > > index 7f4ef66..d38d3c2 100644 > > --- a/include/linux/virtio_config.h > > +++ b/include/linux/virtio_config.h > > @@ -4,6 +4,7 @@ > > #include > > #include > > #include > > +#include > > What patch creates this file? Oops I forgot to git add it. Will resend. > > #include > > > > /** > > @@ -152,6 +153,21 @@ int virtqueue_set_affinity(struct virtqueue *vq, int cpu) > > return 0; > > } > > > > +/* Memory accessors */ > > +#define DEFINE_VIRTIO_XX_TO_CPU(bits) \ > > +static inline u##bits virtio##bits##_to_cpu(struct virtio_device *vdev, __virtio##bits val) \ > > +{ \ > > + return __virtio##bits##_to_cpu(false, val); \ > > +} \ > > +static inline __virtio##bits cpu_to_virtio##bits(struct virtio_device *vdev, u##bits val) \ > > +{ \ > > + return __cpu_to_virtio##bits(false, val); \ > > +} > > + > > +DEFINE_VIRTIO_XX_TO_CPU(16) > > +DEFINE_VIRTIO_XX_TO_CPU(32) > > +DEFINE_VIRTIO_XX_TO_CPU(64) > > + > > /* Config space accessors. */ > > #define virtio_cread(vdev, structname, member, ptr) \ > > do { \ > > 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 > > @@ -32,6 +32,7 @@ > > * > > * Copyright Rusty Russell IBM Corporation 2007. */ > > #include > > +#include > > > > /* This marks a buffer as continuing via the next field. */ > > #define VRING_DESC_F_NEXT 1 > > @@ -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; > > }; > > How does __virtio64 differ from __le64? > > Thanks, > Chris __le64 would require cpu_to_le, I wanted to force the use of our byte swapping macros. > -- > Qualcomm Innovation Center, Inc. > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, > a Linux Foundation Collaborative Project