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Commit 7d824109 authored by Greg Kurz's avatar Greg Kurz Committed by Michael S. Tsirkin
Browse files

virtio: add explicit big-endian support to memory accessors 



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: default avatarGreg Kurz <gkurz@linux.vnet.ibm.com>

Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
parent ab27c07f

drivers/net/macvtap.c

+2 −1
Original line number Diff line number Diff line
@@ -51,7 +51,8 @@ struct macvtap_queue { 


static inline bool macvtap_is_little_endian(struct macvtap_queue *q)

{

	return q->flags & MACVTAP_VNET_LE;

	return q->flags & MACVTAP_VNET_LE ||

		virtio_legacy_is_little_endian();

}



static inline u16 macvtap16_to_cpu(struct macvtap_queue *q, __virtio16 val)

drivers/net/tun.c

+2 −1
Original line number Diff line number Diff line
@@ -208,7 +208,8 @@ struct tun_struct { 


static inline bool tun_is_little_endian(struct tun_struct *tun)

{

	return tun->flags & TUN_VNET_LE;

	return tun->flags & TUN_VNET_LE ||

		virtio_legacy_is_little_endian();

}



static inline u16 tun16_to_cpu(struct tun_struct *tun, __virtio16 val)

drivers/vhost/vhost.h

+2 −1
Original line number Diff line number Diff line
@@ -175,7 +175,8 @@ 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);

	return vhost_has_feature(vq, VIRTIO_F_VERSION_1) ||

		virtio_legacy_is_little_endian();

}



/* Memory accessors */

include/linux/virtio_byteorder.h

+14 −10
Original line number Diff line number Diff line
@@ -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 */

include/linux/virtio_config.h

+2 −1
Original line number Diff line number Diff line
@@ -207,7 +207,8 @@ 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);

	return virtio_has_feature(vdev, VIRTIO_F_VERSION_1) ||

		virtio_legacy_is_little_endian();

}



/* Memory accessors */