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virtio: add explicit big-endian support to memory accessors

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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 <gkurz@linux.vnet.ibm.com>

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Greg Kurz 2015-04-24 14:26:24 +02:00 • committed by Michael S. Tsirkin
parent ab27c07f60
commit 7d82410950
6 changed files with 24 additions and 15 deletions
Download patch file Download diff file Expand all files Collapse all files

24
include/linux/virtio_byteorder.h
View file

@ -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 __virtio64)cpu_to_le64(val);
else
return (__force __virtio64)val;
return (__force __virtio64)cpu_to_be64(val);
}
#endif /* _LINUX_VIRTIO_BYTEORDER */