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virtio: simplify config mechanism.

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Previously we used a type/len pair within the config space, but this
seems overkill.  We now simply define a structure which represents the
layout in the config space: the config space can now only be extended
at the end.

The main driver-visible changes:
1) We indicate what fields are present with an explicit feature bit.
2) Virtqueues are explicitly numbered, and not in the config space.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2008-02-04 23:49:56 -05:00
parent f35d9d8aae
commit a586d4f601
11 changed files with 278 additions and 279 deletions
Download patch file Download diff file Expand all files Collapse all files

9
include/linux/lguest_launcher.h
View file

@ -23,7 +23,12 @@
struct lguest_device_desc {
/* The device type: console, network, disk etc. Type 0 terminates. */
__u8 type;
/* The number of bytes of the config array. */
/* The number of virtqueues (first in config array) */
__u8 num_vq;
/* The number of bytes of feature bits. Multiply by 2: one for host
* features and one for guest acknowledgements. */
__u8 feature_len;
/* The number of bytes of the config array after virtqueues. */
__u8 config_len;
/* A status byte, written by the Guest. */
__u8 status;
@ -31,7 +36,7 @@ struct lguest_device_desc {
};
/*D:135 This is how we expect the device configuration field for a virtqueue
* (type VIRTIO_CONFIG_F_VIRTQUEUE) to be laid out: */
* to be laid out in config space. */
struct lguest_vqconfig {
/* The number of entries in the virtio_ring */
__u16 num;

20
include/linux/virtio_blk.h
View file

@ -6,15 +6,19 @@
#define VIRTIO_ID_BLOCK 2
/* Feature bits */
#define VIRTIO_CONFIG_BLK_F 0x40
#define VIRTIO_BLK_F_BARRIER 1 /* Does host support barriers? */
#define VIRTIO_BLK_F_BARRIER 0 /* Does host support barriers? */
#define VIRTIO_BLK_F_SIZE_MAX 1 /* Indicates maximum segment size */
#define VIRTIO_BLK_F_SEG_MAX 2 /* Indicates maximum # of segments */
/* The capacity (in 512-byte sectors). */
#define VIRTIO_CONFIG_BLK_F_CAPACITY 0x41
/* The maximum segment size. */
#define VIRTIO_CONFIG_BLK_F_SIZE_MAX 0x42
/* The maximum number of segments. */
#define VIRTIO_CONFIG_BLK_F_SEG_MAX 0x43
struct virtio_blk_config
{
/* The capacity (in 512-byte sectors). */
__le64 capacity;
/* The maximum segment size (if VIRTIO_BLK_F_SIZE_MAX) */
__le32 size_max;
/* The maximum number of segments (if VIRTIO_BLK_F_SEG_MAX) */
__le32 seg_max;
} __attribute__((packed));
/* These two define direction. */
#define VIRTIO_BLK_T_IN 0

98
include/linux/virtio_config.h
View file

@ -5,7 +5,7 @@
* store and access that space differently. */
#include <linux/types.h>
/* Status byte for guest to report progress, and synchronize config. */
/* Status byte for guest to report progress, and synchronize features. */
/* We have seen device and processed generic fields (VIRTIO_CONFIG_F_VIRTIO) */
#define VIRTIO_CONFIG_S_ACKNOWLEDGE 1
/* We have found a driver for the device. */
@ -15,34 +15,27 @@
/* We've given up on this device. */
#define VIRTIO_CONFIG_S_FAILED 0x80
/* Feature byte (actually 7 bits availabe): */
/* Requirements/features of the virtio implementation. */
#define VIRTIO_CONFIG_F_VIRTIO 1
/* Requirements/features of the virtqueue (may have more than one). */
#define VIRTIO_CONFIG_F_VIRTQUEUE 2
#ifdef __KERNEL__
struct virtio_device;
/**
* virtio_config_ops - operations for configuring a virtio device
* @find: search for the next configuration field of the given type.
* @feature: search for a feature in this config
* vdev: the virtio_device
* type: the feature type
* len: the (returned) length of the field if found.
* Returns a token if found, or NULL. Never returnes the same field twice
* (ie. it's used up).
* @get: read the value of a configuration field after find().
* bit: the feature bit
* Returns true if the feature is supported. Acknowledges the feature
* so the host can see it.
* @get: read the value of a configuration field
* vdev: the virtio_device
* token: the token returned from find().
* offset: the offset of the configuration field
* buf: the buffer to write the field value into.
* len: the length of the buffer (given by find()).
* len: the length of the buffer
* Note that contents are conventionally little-endian.
* @set: write the value of a configuration field after find().
* @set: write the value of a configuration field
* vdev: the virtio_device
* token: the token returned from find().
* offset: the offset of the configuration field
* buf: the buffer to read the field value from.
* len: the length of the buffer (given by find()).
* len: the length of the buffer
* Note that contents are conventionally little-endian.
* @get_status: read the status byte
* vdev: the virtio_device
@ -50,62 +43,63 @@ struct virtio_device;
* @set_status: write the status byte
* vdev: the virtio_device
* status: the new status byte
* @find_vq: find the first VIRTIO_CONFIG_F_VIRTQUEUE and create a virtqueue.
* @find_vq: find a virtqueue and instantiate it.
* vdev: the virtio_device
* index: the 0-based virtqueue number in case there's more than one.
* callback: the virqtueue callback
* Returns the new virtqueue or ERR_PTR().
* Returns the new virtqueue or ERR_PTR() (eg. -ENOENT).
* @del_vq: free a virtqueue found by find_vq().
*/
struct virtio_config_ops
{
void *(*find)(struct virtio_device *vdev, u8 type, unsigned *len);
void (*get)(struct virtio_device *vdev, void *token,
bool (*feature)(struct virtio_device *vdev, unsigned bit);
void (*get)(struct virtio_device *vdev, unsigned offset,
void *buf, unsigned len);
void (*set)(struct virtio_device *vdev, void *token,
void (*set)(struct virtio_device *vdev, unsigned offset,
const void *buf, unsigned len);
u8 (*get_status)(struct virtio_device *vdev);
void (*set_status)(struct virtio_device *vdev, u8 status);
struct virtqueue *(*find_vq)(struct virtio_device *vdev,
unsigned index,
bool (*callback)(struct virtqueue *));
void (*del_vq)(struct virtqueue *vq);
};
/**
* virtio_config_val - get a single virtio config and mark it used.
* @config: the virtio config space
* @type: the type to search for.
* virtio_config_val - look for a feature and get a single virtio config.
* @vdev: the virtio device
* @fbit: the feature bit
* @offset: the type to search for.
* @val: a pointer to the value to fill in.
*
* Once used, the config type is marked with VIRTIO_CONFIG_F_USED so it can't
* be found again. This version does endian conversion. */
#define virtio_config_val(vdev, type, v) ({ \
int _err = __virtio_config_val((vdev),(type),(v),sizeof(*(v))); \
\
BUILD_BUG_ON(sizeof(*(v)) != 1 && sizeof(*(v)) != 2 \
&& sizeof(*(v)) != 4 && sizeof(*(v)) != 8); \
if (!_err) { \
switch (sizeof(*(v))) { \
case 2: le16_to_cpus((__u16 *) v); break; \
case 4: le32_to_cpus((__u32 *) v); break; \
case 8: le64_to_cpus((__u64 *) v); break; \
} \
} \
* The return value is -ENOENT if the feature doesn't exist. Otherwise
* the value is endian-corrected and returned in v. */
#define virtio_config_val(vdev, fbit, offset, v) ({ \
int _err; \
if ((vdev)->config->feature((vdev), (fbit))) { \
__virtio_config_val((vdev), (offset), (v)); \
_err = 0; \
} else \
_err = -ENOENT; \
_err; \
})
int __virtio_config_val(struct virtio_device *dev,
u8 type, void *val, size_t size);
/**
* virtio_use_bit - helper to use a feature bit in a bitfield value.
* @dev: the virtio device
* @token: the token as returned from vdev->config->find().
* @len: the length of the field.
* @bitnum: the bit to test.
* __virtio_config_val - get a single virtio config without feature check.
* @vdev: the virtio device
* @offset: the type to search for.
* @val: a pointer to the value to fill in.
*
* If handed a NULL token, it returns false, otherwise returns bit status.
* If it's one, it sets the mirroring acknowledgement bit. */
int virtio_use_bit(struct virtio_device *vdev,
void *token, unsigned int len, unsigned int bitnum);
* The value is endian-corrected and returned in v. */
#define __virtio_config_val(vdev, offset, v) do { \
BUILD_BUG_ON(sizeof(*(v)) != 1 && sizeof(*(v)) != 2 \
&& sizeof(*(v)) != 4 && sizeof(*(v)) != 8); \
(vdev)->config->get((vdev), (offset), (v), sizeof(*(v))); \
switch (sizeof(*(v))) { \
case 2: le16_to_cpus((__u16 *) v); break; \
case 4: le32_to_cpus((__u32 *) v); break; \
case 8: le64_to_cpus((__u64 *) v); break; \
} \
} while(0)
#endif /* __KERNEL__ */
#endif /* _LINUX_VIRTIO_CONFIG_H */

11
include/linux/virtio_net.h
View file

@ -5,16 +5,19 @@
/* The ID for virtio_net */
#define VIRTIO_ID_NET 1
/* The bitmap of config for virtio net */
#define VIRTIO_CONFIG_NET_F 0x40
/* The feature bitmap for virtio net */
#define VIRTIO_NET_F_NO_CSUM 0
#define VIRTIO_NET_F_TSO4 1
#define VIRTIO_NET_F_UFO 2
#define VIRTIO_NET_F_TSO4_ECN 3
#define VIRTIO_NET_F_TSO6 4
#define VIRTIO_NET_F_MAC 5
/* The config defining mac address. */
#define VIRTIO_CONFIG_NET_MAC_F 0x41
struct virtio_net_config
{
/* The config defining mac address (if VIRTIO_NET_F_MAC) */
__u8 mac[6];
} __attribute__((packed));
/* This is the first element of the scatter-gather list. If you don't
* specify GSO or CSUM features, you can simply ignore the header. */