Re: [PATCH v3 6/7] virtio: add explicit big-endian support to memory accessors

2015-04-21 Thread Greg Kurz 
On Tue, 7 Apr 2015 17:56:25 +0200
"Michael S. Tsirkin"  wrote:

> On Tue, Apr 07, 2015 at 02:15:52PM +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 
> > ---
> >  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();
> >  }
> >  
> >  static inline u16 macvtap16_to_cpu(struct macvtap_queue *q, __virtio16 val)
> 
> Hmm I'm not sure how well this will work once you
> actually make it dynamic.
> Remains to be seen.
> 

Oops I overlooked this mail... FWIW I could reboot/kexec from a ppc64 guest
to ppc64le and back with the following QEMU:

https://github.com/gkurz/qemu/commits/vhost/cross-endian

> > 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

Re: [PATCH v3 6/7] virtio: add explicit big-endian support to memory accessors

2015-04-21 Thread Greg Kurz 
On Tue, 7 Apr 2015 17:56:25 +0200
Michael S. Tsirkin m...@redhat.com wrote:

 On Tue, Apr 07, 2015 at 02:15:52PM +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 gk...@linux.vnet.ibm.com
  ---
   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();
   }
   
   static inline u16 macvtap16_to_cpu(struct macvtap_queue *q, __virtio16 val)
 
 Hmm I'm not sure how well this will work once you
 actually make it dynamic.
 Remains to be seen.
 

Oops I overlooked this mail... FWIW I could reboot/kexec from a ppc64 guest
to ppc64le and back with the following QEMU:

https://github.com/gkurz/qemu/commits/vhost/cross-endian

  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 linux/types.h
   #include uapi/linux/virtio_types.h
   
  -/*
  - * 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,

Re: [PATCH v3 6/7] virtio: add explicit big-endian support to memory accessors

2015-04-07 Thread Michael S. Tsirkin 
On Tue, Apr 07, 2015 at 02:15:52PM +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 
> ---
>  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();
>  }
>  
>  static inline u16 macvtap16_to_cpu(struct macvtap_queue *q, __virtio16 val)

Hmm I'm not sure how well this will work once you
actually make it dynamic.
Remains to be seen.

> 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;

[PATCH v3 6/7] virtio: add explicit big-endian support to memory accessors

2015-04-07 Thread Greg Kurz 
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 
---
 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();
 }
 
 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

[PATCH v3 6/7] virtio: add explicit big-endian support to memory accessors

2015-04-07 Thread Greg Kurz 
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 gk...@linux.vnet.ibm.com
---
 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();
 }
 
 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 linux/types.h
 #include uapi/linux/virtio_types.h
 
-/*
- * 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

Re: [PATCH v3 6/7] virtio: add explicit big-endian support to memory accessors

2015-04-07 Thread Michael S. Tsirkin 
On Tue, Apr 07, 2015 at 02:15:52PM +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 gk...@linux.vnet.ibm.com
 ---
  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();
  }
  
  static inline u16 macvtap16_to_cpu(struct macvtap_queue *q, __virtio16 val)

Hmm I'm not sure how well this will work once you
actually make it dynamic.
Remains to be seen.

 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 linux/types.h
  #include uapi/linux/virtio_types.h
  
 -/*
 - * 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