tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1#ifndef _LINUX_LGUEST_LAUNCHER
2#define _LINUX_LGUEST_LAUNCHER
3/* Everything the "lguest" userspace program needs to know. */
4#include <linux/types.h>
5
6/*D:010
7 * Drivers
8 *
9 * The Guest needs devices to do anything useful. Since we don't let it touch
10 * real devices (think of the damage it could do!) we provide virtual devices.
11 * We could emulate a PCI bus with various devices on it, but that is a fairly
12 * complex burden for the Host and suboptimal for the Guest, so we have our own
13 * simple lguest bus and we use "virtio" drivers. These drivers need a set of
14 * routines from us which will actually do the virtual I/O, but they handle all
15 * the net/block/console stuff themselves. This means that if we want to add
16 * a new device, we simply need to write a new virtio driver and create support
17 * for it in the Launcher: this code won't need to change.
18 *
19 * Virtio devices are also used by kvm, so we can simply reuse their optimized
20 * device drivers. And one day when everyone uses virtio, my plan will be
21 * complete. Bwahahahah!
22 *
23 * Devices are described by a simplified ID, a status byte, and some "config"
24 * bytes which describe this device's configuration. This is placed by the
25 * Launcher just above the top of physical memory:
26 */
27struct lguest_device_desc {
28 /* The device type: console, network, disk etc. Type 0 terminates. */
29 __u8 type;
30 /* The number of virtqueues (first in config array) */
31 __u8 num_vq;
32 /* The number of bytes of feature bits. Multiply by 2: one for host
33 * features and one for Guest acknowledgements. */
34 __u8 feature_len;
35 /* The number of bytes of the config array after virtqueues. */
36 __u8 config_len;
37 /* A status byte, written by the Guest. */
38 __u8 status;
39 __u8 config[0];
40};
41
42/*D:135 This is how we expect the device configuration field for a virtqueue
43 * to be laid out in config space. */
44struct lguest_vqconfig {
45 /* The number of entries in the virtio_ring */
46 __u16 num;
47 /* The interrupt we get when something happens. */
48 __u16 irq;
49 /* The page number of the virtio ring for this device. */
50 __u32 pfn;
51};
52/*:*/
53
54/* Write command first word is a request. */
55enum lguest_req
56{
57 LHREQ_INITIALIZE, /* + base, pfnlimit, pgdir, start */
58 LHREQ_GETDMA, /* No longer used */
59 LHREQ_IRQ, /* + irq */
60 LHREQ_BREAK, /* + on/off flag (on blocks until someone does off) */
61};
62#endif /* _LINUX_LGUEST_LAUNCHER */