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Commit eef960a0 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin
Browse files

virtio: memory access APIs 



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
query device endian-ness and act accordingly.

Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
parent 4ec22fae

include/linux/virtio_byteorder.h

0 → 100644
+59 −0
Original line number Diff line number Diff line 
#ifndef _LINUX_VIRTIO_BYTEORDER_H

#define _LINUX_VIRTIO_BYTEORDER_H

#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 u16 __virtio16_to_cpu(bool little_endian, __virtio16 val)

{

	if (little_endian)

		return le16_to_cpu((__force __le16)val);

	else

		return (__force u16)val;

}



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;

}



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;

}



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;

}



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;

}



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;

}



#endif /* _LINUX_VIRTIO_BYTEORDER */

include/linux/virtio_config.h

+32 −0
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 
#include <linux/err.h>

#include <linux/bug.h>

#include <linux/virtio.h>

#include <linux/virtio_byteorder.h>

#include <uapi/linux/virtio_config.h>



/**
@@ -199,6 +200,37 @@ int virtqueue_set_affinity(struct virtqueue *vq, int cpu) 
	return 0;

}



/* Memory accessors */

static inline u16 virtio16_to_cpu(struct virtio_device *vdev, __virtio16 val)

{

	return __virtio16_to_cpu(virtio_has_feature(vdev, VIRTIO_F_VERSION_1), val);

}



static inline __virtio16 cpu_to_virtio16(struct virtio_device *vdev, u16 val)

{

	return __cpu_to_virtio16(virtio_has_feature(vdev, VIRTIO_F_VERSION_1), val);

}



static inline u32 virtio32_to_cpu(struct virtio_device *vdev, __virtio32 val)

{

	return __virtio32_to_cpu(virtio_has_feature(vdev, VIRTIO_F_VERSION_1), val);

}



static inline __virtio32 cpu_to_virtio32(struct virtio_device *vdev, u32 val)

{

	return __cpu_to_virtio32(virtio_has_feature(vdev, VIRTIO_F_VERSION_1), val);

}



static inline u64 virtio64_to_cpu(struct virtio_device *vdev, __virtio64 val)

{

	return __virtio64_to_cpu(virtio_has_feature(vdev, VIRTIO_F_VERSION_1), val);

}



static inline __virtio64 cpu_to_virtio64(struct virtio_device *vdev, u64 val)

{

	return __cpu_to_virtio64(virtio_has_feature(vdev, VIRTIO_F_VERSION_1), val);

}



/* Config space accessors. */

#define virtio_cread(vdev, structname, member, ptr)			\

	do {								\

include/uapi/linux/Kbuild

+1 −0
Original line number Diff line number Diff line
@@ -423,6 +423,7 @@ header-y += virtio_blk.h 
header-y += virtio_config.h

header-y += virtio_console.h

header-y += virtio_ids.h

header-y += virtio_types.h

header-y += virtio_net.h

header-y += virtio_pci.h

header-y += virtio_ring.h

include/uapi/linux/virtio_ring.h

+23 −22
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ 
 *

 * Copyright Rusty Russell IBM Corporation 2007. */

#include <linux/types.h>

#include <linux/virtio_types.h>



/* 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;

};



struct vring_avail {

	__u16 flags;

	__u16 idx;

	__u16 ring[];

	__virtio16 flags;

	__virtio16 idx;

	__virtio16 ring[];

};



/* u32 is used here for ids for padding reasons. */

struct vring_used_elem {

	/* Index of start of used descriptor chain. */

	__u32 id;

	__virtio32 id;

	/* Total length of the descriptor chain which was used (written to) */

	__u32 len;

	__virtio32 len;

};



struct vring_used {

	__u16 flags;

	__u16 idx;

	__virtio16 flags;

	__virtio16 idx;

	struct vring_used_elem ring[];

};
@@ -109,25 +110,25 @@ struct vring { 
 *	struct vring_desc desc[num];

 *

 *	// A ring of available descriptor heads with free-running index.

 *	__u16 avail_flags;

 *	__u16 avail_idx;

 *	__u16 available[num];

 *	__u16 used_event_idx;

 *	__virtio16 avail_flags;

 *	__virtio16 avail_idx;

 *	__virtio16 available[num];

 *	__virtio16 used_event_idx;

 *

 *	// Padding to the next align boundary.

 *	char pad[];

 *

 *	// A ring of used descriptor heads with free-running index.

 *	__u16 used_flags;

 *	__u16 used_idx;

 *	__virtio16 used_flags;

 *	__virtio16 used_idx;

 *	struct vring_used_elem used[num];

 *	__u16 avail_event_idx;

 *	__virtio16 avail_event_idx;

 * };

 */

/* We publish the used event index at the end of the available ring, and vice

 * versa. They are at the end for backwards compatibility. */

#define vring_used_event(vr) ((vr)->avail->ring[(vr)->num])

#define vring_avail_event(vr) (*(__u16 *)&(vr)->used->ring[(vr)->num])

#define vring_avail_event(vr) (*(__virtio16 *)&(vr)->used->ring[(vr)->num])



static inline void vring_init(struct vring *vr, unsigned int num, void *p,

			      unsigned long align)
@@ -135,15 +136,15 @@ static inline void vring_init(struct vring *vr, unsigned int num, void *p, 
	vr->num = num;

	vr->desc = p;

	vr->avail = p + num*sizeof(struct vring_desc);

	vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + sizeof(__u16)

	vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + sizeof(__virtio16)

		+ align-1) & ~(align - 1));

}



static inline unsigned vring_size(unsigned int num, unsigned long align)

{

	return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (3 + num)

	return ((sizeof(struct vring_desc) * num + sizeof(__virtio16) * (3 + num)

		 + align - 1) & ~(align - 1))

		+ sizeof(__u16) * 3 + sizeof(struct vring_used_elem) * num;

		+ sizeof(__virtio16) * 3 + sizeof(struct vring_used_elem) * num;

}



/* The following is used with USED_EVENT_IDX and AVAIL_EVENT_IDX */

include/uapi/linux/virtio_types.h

0 → 100644
+46 −0
Original line number Diff line number Diff line 
#ifndef _UAPI_LINUX_VIRTIO_TYPES_H

#define _UAPI_LINUX_VIRTIO_TYPES_H

/* Type definitions for virtio implementations.

 *

 * This header is BSD licensed so anyone can use the definitions to implement

 * compatible drivers/servers.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. Neither the name of IBM nor the names of its contributors

 *    may be used to endorse or promote products derived from this software

 *    without specific prior written permission.

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND

 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

 * ARE DISCLAIMED.  IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE

 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

 * SUCH DAMAGE.

 *

 * Copyright (C) 2014 Red Hat, Inc.

 * Author: Michael S. Tsirkin <mst@redhat.com>

 */

#include <linux/types.h>



/*

 * __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

 */



typedef __u16 __bitwise__ __virtio16;

typedef __u32 __bitwise__ __virtio32;

typedef __u64 __bitwise__ __virtio64;



#endif /* _UAPI_LINUX_VIRTIO_TYPES_H */