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Lguest support for Virtio

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This makes lguest able to use the virtio devices.

We change the device descriptor page from a simple array to a variable
length "type, config_len, status, config data..." format, and
implement virtio_config_ops to read from that config data.

We use the virtio ring implementation for an efficient Guest <-> Host
virtqueue mechanism, and the new LHCALL_NOTIFY hypercall to kick the
host when it changes.

We also use LHCALL_NOTIFY on kernel addresses for very very early
console output.  We could have another hypercall, but this hack works
quite well.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2007-10-22 11:24:21 +10:00
parent 15045275c3
commit 19f1537b7b
5 changed files with 421 additions and 28 deletions
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47
include/linux/lguest_launcher.h
View file

@ -22,37 +22,28 @@
* complex burden for the Host and suboptimal for the Guest, so we have our own
* "lguest" bus and simple drivers.
*
* Devices are described by an array of LGUEST_MAX_DEVICES of these structs,
* placed by the Launcher just above the top of physical memory:
* Devices are described by a simplified ID, a status byte, and some "config"
* bytes which describe this device's configuration. This is placed by the
* Launcher just above the top of physical memory:
*/
struct lguest_device_desc {
/* The device type: console, network, disk etc. */
__u16 type;
#define LGUEST_DEVICE_T_CONSOLE 1
#define LGUEST_DEVICE_T_NET 2
#define LGUEST_DEVICE_T_BLOCK 3
/* The device type: console, network, disk etc. Type 0 terminates. */
__u8 type;
/* The number of bytes of the config array. */
__u8 config_len;
/* A status byte, written by the Guest. */
__u8 status;
__u8 config[0];
};
/* The specific features of this device: these depends on device type
* except for LGUEST_DEVICE_F_RANDOMNESS. */
__u16 features;
#define LGUEST_NET_F_NOCSUM 0x4000 /* Don't bother checksumming */
#define LGUEST_DEVICE_F_RANDOMNESS 0x8000 /* IRQ is fairly random */
/* This is how the Guest reports status of the device: the Host can set
* LGUEST_DEVICE_S_REMOVED to indicate removal, but the rest are only
* ever manipulated by the Guest, and only ever set. */
__u16 status;
/* 256 and above are device specific. */
#define LGUEST_DEVICE_S_ACKNOWLEDGE 1 /* We have seen device. */
#define LGUEST_DEVICE_S_DRIVER 2 /* We have found a driver */
#define LGUEST_DEVICE_S_DRIVER_OK 4 /* Driver says OK! */
#define LGUEST_DEVICE_S_REMOVED 8 /* Device has gone away. */
#define LGUEST_DEVICE_S_REMOVED_ACK 16 /* Driver has been told. */
#define LGUEST_DEVICE_S_FAILED 128 /* Something actually failed */
/* Each device exists somewhere in Guest physical memory, over some
* number of pages. */
__u16 num_pages;
/*D:135 This is how we expect the device configuration field for a virtqueue
* (type VIRTIO_CONFIG_F_VIRTQUEUE) to be laid out: */
struct lguest_vqconfig {
/* The number of entries in the virtio_ring */
__u16 num;
/* The interrupt we get when something happens. */
__u16 irq;
/* The page number of the virtio ring for this device. */
__u32 pfn;
};
/*:*/