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.

Michael S. Tsirkin committed 12 years ago

Commit eef960a1 parent 4ec22fa5 files · +161 −22Browse files

Showing the changes to include/uapi/linux (3 of 5 files). Show all

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3 files

include/uapi/linux/Kbuild +1 −0
include/uapi/linux/virtio_ring.h +23 −22
include/uapi/linux/virtio_types.h +46 −0

include/uapi/linux/Kbuild+1−0

@@ -423,6 +423,7 @@ header-y += virtio_blk.h · 422 unmodified lines
423	423	header-y += virtio_config.h
424	424	header-y += virtio_console.h
425	425	header-y += virtio_ids.h
	426	+header-y += virtio_types.h
426	427	header-y += virtio_net.h
427	428	header-y += virtio_pci.h
428	429	header-y += virtio_ring.h

include/uapi/linux/virtio_ring.h+23−22

@@ -32,6 +32,7 @@ · 31 unmodified lines
32	32	*
33	33	* Copyright Rusty Russell IBM Corporation 2007. */
34	34	#include <linux/types.h>
	35	+#include <linux/virtio_types.h>
35	36
36	37	/* This marks a buffer as continuing via the next field. */
37	38	#define VRING_DESC_F_NEXT 1
@@ -61,32 +62,32 @@ · 23 unmodified lines
61	62	/* Virtio ring descriptors: 16 bytes. These can chain together via "next". */
62	63	struct vring_desc {
63	64	/* Address (guest-physical). */
64		− __u64 addr;
	65	+ __virtio64 addr;
65	66	/* Length. */
66		− __u32 len;
	67	+ __virtio32 len;
67	68	/* The flags as indicated above. */
68		− __u16 flags;
	69	+ __virtio16 flags;
69	70	/* We chain unused descriptors via this, too */
70		− __u16 next;
	71	+ __virtio16 next;
71	72	};
72	73
73	74	struct vring_avail {
74		− __u16 flags;
75		− __u16 idx;
76		− __u16 ring[];
	75	+ __virtio16 flags;
	76	+ __virtio16 idx;
	77	+ __virtio16 ring[];
77	78	};
78	79
79	80	/* u32 is used here for ids for padding reasons. */
80	81	struct vring_used_elem {
81	82	/* Index of start of used descriptor chain. */
82		− __u32 id;
	83	+ __virtio32 id;
83	84	/* Total length of the descriptor chain which was used (written to) */
84		− __u32 len;
	85	+ __virtio32 len;
85	86	};
86	87
87	88	struct vring_used {
88		− __u16 flags;
89		− __u16 idx;
	89	+ __virtio16 flags;
	90	+ __virtio16 idx;
90	91	struct vring_used_elem ring[];
91	92	};
92	93
@@ -109,25 +110,25 @@ struct vring { · 16 unmodified lines
109	110	* struct vring_desc desc[num];
110	111	*
111	112	* // A ring of available descriptor heads with free-running index.
112		− * __u16 avail_flags;
113		− * __u16 avail_idx;
114		− * __u16 available[num];
115		− * __u16 used_event_idx;
	113	+ * __virtio16 avail_flags;
	114	+ * __virtio16 avail_idx;
	115	+ * __virtio16 available[num];
	116	+ * __virtio16 used_event_idx;
116	117	*
117	118	* // Padding to the next align boundary.
118	119	* char pad[];
119	120	*
120	121	* // A ring of used descriptor heads with free-running index.
121		− * __u16 used_flags;
122		− * __u16 used_idx;
	122	+ * __virtio16 used_flags;
	123	+ * __virtio16 used_idx;
123	124	* struct vring_used_elem used[num];
124		− * __u16 avail_event_idx;
	125	+ * __virtio16 avail_event_idx;
125	126	* };
126	127	*/
127	128	/* We publish the used event index at the end of the available ring, and vice
128	129	* versa. They are at the end for backwards compatibility. */
129	130	#define vring_used_event(vr) ((vr)->avail->ring[(vr)->num])
130		−#define vring_avail_event(vr) ((__u16 )&(vr)->used->ring[(vr)->num])
	131	+#define vring_avail_event(vr) ((__virtio16 )&(vr)->used->ring[(vr)->num])
131	132
132	133	static inline void vring_init(struct vring vr, unsigned int num, void p,
133	134	unsigned long align)
@@ -135,15 +136,15 @@ static inline void vring_init(struct vring vr, unsigned int num, void p, · 1 unmodified line
135	136	vr->num = num;
136	137	vr->desc = p;
137	138	vr->avail = p + num*sizeof(struct vring_desc);
138		− vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + sizeof(__u16)
	139	+ vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + sizeof(__virtio16)
139	140	+ align-1) & ~(align - 1));
140	141	}
141	142
142	143	static inline unsigned vring_size(unsigned int num, unsigned long align)
143	144	{
144		− return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (3 + num)
	145	+ return ((sizeof(struct vring_desc) * num + sizeof(__virtio16) * (3 + num)
145	146	+ align - 1) & ~(align - 1))
146		− + sizeof(__u16) * 3 + sizeof(struct vring_used_elem) * num;
	147	+ + sizeof(__virtio16) * 3 + sizeof(struct vring_used_elem) * num;
147	148	}
148	149
149	150	/* The following is used with USED_EVENT_IDX and AVAIL_EVENT_IDX */

include/uapi/linux/virtio_types.h+46−0

@@ -0,0 +1,46 @@
	1	+#ifndef _UAPI_LINUX_VIRTIO_TYPES_H
	2	+#define _UAPI_LINUX_VIRTIO_TYPES_H
	3	+/* Type definitions for virtio implementations.
	4	+ *
	5	+ * This header is BSD licensed so anyone can use the definitions to implement
	6	+ * compatible drivers/servers.
	7	+ *
	8	+ * Redistribution and use in source and binary forms, with or without
	9	+ * modification, are permitted provided that the following conditions
	10	+ * are met:
	11	+ * 1. Redistributions of source code must retain the above copyright
	12	+ * notice, this list of conditions and the following disclaimer.
	13	+ * 2. Redistributions in binary form must reproduce the above copyright
	14	+ * notice, this list of conditions and the following disclaimer in the
	15	+ * documentation and/or other materials provided with the distribution.
	16	+ * 3. Neither the name of IBM nor the names of its contributors
	17	+ * may be used to endorse or promote products derived from this software
	18	+ * without specific prior written permission.
	19	+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND
	20	+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	21	+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	22	+ * ARE DISCLAIMED. IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE
	23	+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	24	+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	25	+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	26	+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	27	+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	28	+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	29	+ * SUCH DAMAGE.
	30	+ *
	31	+ * Copyright (C) 2014 Red Hat, Inc.
	32	+ * Author: Michael S. Tsirkin <mst@redhat.com>
	33	+ */
	34	+#include <linux/types.h>
	35	+
	36	+/*
	37	+ * __virtio{16,32,64} have the following meaning:
	38	+ * - __u{16,32,64} for virtio devices in legacy mode, accessed in native endian
	39	+ * - __le{16,32,64} for standard-compliant virtio devices
	40	+ */
	41	+
	42	+typedef __u16 __bitwise__ __virtio16;
	43	+typedef __u32 __bitwise__ __virtio32;
	44	+typedef __u64 __bitwise__ __virtio64;
	45	+
	46	+#endif /* _UAPI_LINUX_VIRTIO_TYPES_H */