1 #ifndef _LINUX_LGUEST_LAUNCHER
2 #define _LINUX_LGUEST_LAUNCHER
3 /* Everything the "lguest" userspace program needs to know. */
4 #include <linux/types.h>
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.
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!
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:
27 struct lguest_device_desc {
28 /* The device type: console, network, disk etc. Type 0 terminates. */
30 /* The number of virtqueues (first in config array) */
32 /* The number of bytes of feature bits. Multiply by 2: one for host
33 * features and one for Guest acknowledgements. */
35 /* The number of bytes of the config array after virtqueues. */
37 /* A status byte, written by the Guest. */
42 /*D:135 This is how we expect the device configuration field for a virtqueue
43 * to be laid out in config space. */
44 struct lguest_vqconfig {
45 /* The number of entries in the virtio_ring */
47 /* The interrupt we get when something happens. */
49 /* The page number of the virtio ring for this device. */
54 /* Write command first word is a request. */
57 LHREQ_INITIALIZE, /* + base, pfnlimit, start */
58 LHREQ_GETDMA, /* No longer used */
59 LHREQ_IRQ, /* + irq */
60 LHREQ_BREAK, /* No longer used */
61 LHREQ_EVENTFD, /* + address, fd. */
64 /* The alignment to use between consumer and producer parts of vring.
65 * x86 pagesize for historical reasons. */
66 #define LGUEST_VRING_ALIGN 4096
67 #endif /* _LINUX_LGUEST_LAUNCHER */