diff options
Diffstat (limited to 'include/linux/lguest_launcher.h')
| -rw-r--r-- | include/linux/lguest_launcher.h | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/include/linux/lguest_launcher.h b/include/linux/lguest_launcher.h new file mode 100644 index 00000000000..495203ff221 --- /dev/null +++ b/include/linux/lguest_launcher.h @@ -0,0 +1,73 @@ +#ifndef _LINUX_LGUEST_LAUNCHER +#define _LINUX_LGUEST_LAUNCHER +/* Everything the "lguest" userspace program needs to know. */ +#include <linux/types.h> + +/*D:010 + * Drivers + * + * The Guest needs devices to do anything useful. Since we don't let it touch + * real devices (think of the damage it could do!) we provide virtual devices. + * We could emulate a PCI bus with various devices on it, but that is a fairly + * complex burden for the Host and suboptimal for the Guest, so we have our own + * simple lguest bus and we use "virtio" drivers. These drivers need a set of + * routines from us which will actually do the virtual I/O, but they handle all + * the net/block/console stuff themselves. This means that if we want to add + * a new device, we simply need to write a new virtio driver and create support + * for it in the Launcher: this code won't need to change. + * + * Virtio devices are also used by kvm, so we can simply reuse their optimized + * device drivers. And one day when everyone uses virtio, my plan will be + * complete. Bwahahahah! + * + * 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. Type 0 terminates. */ + __u8 type; + /* 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; + __u8 config[0]; +}; + +/*D:135 + * This is how we expect the device configuration field for a virtqueue + * to be laid out in config space. + */ +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; +}; +/*:*/ + +/* Write command first word is a request. */ +enum lguest_req +{ + LHREQ_INITIALIZE, /* + base, pfnlimit, start */ + LHREQ_GETDMA, /* No longer used */ + LHREQ_IRQ, /* + irq */ + LHREQ_BREAK, /* No longer used */ + LHREQ_EVENTFD, /* + address, fd. */ +}; + +/* + * The alignment to use between consumer and producer parts of vring. + * x86 pagesize for historical reasons. + */ +#define LGUEST_VRING_ALIGN 4096 +#endif /* _LINUX_LGUEST_LAUNCHER */ |