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

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
#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 */
......@@ -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 { \
......
......@@ -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
......
......@@ -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 */
......
#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 */
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