| 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 | */ |
| 27 | struct 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 | /* |
| 33 | * The number of bytes of feature bits. Multiply by 2: one for host |
| 34 | * features and one for Guest acknowledgements. |
| 35 | */ |
| 36 | __u8 feature_len; |
| 37 | /* The number of bytes of the config array after virtqueues. */ |
| 38 | __u8 config_len; |
| 39 | /* A status byte, written by the Guest. */ |
| 40 | __u8 status; |
| 41 | __u8 config[0]; |
| 42 | }; |
| 43 | |
| 44 | /*D:135 |
| 45 | * This is how we expect the device configuration field for a virtqueue |
| 46 | * to be laid out in config space. |
| 47 | */ |
| 48 | struct lguest_vqconfig { |
| 49 | /* The number of entries in the virtio_ring */ |
| 50 | __u16 num; |
| 51 | /* The interrupt we get when something happens. */ |
| 52 | __u16 irq; |
| 53 | /* The page number of the virtio ring for this device. */ |
| 54 | __u32 pfn; |
| 55 | }; |
| 56 | /*:*/ |
| 57 | |
| 58 | /* Write command first word is a request. */ |
| 59 | enum lguest_req |
| 60 | { |
| 61 | LHREQ_INITIALIZE, /* + base, pfnlimit, start */ |
| 62 | LHREQ_GETDMA, /* No longer used */ |
| 63 | LHREQ_IRQ, /* + irq */ |
| 64 | LHREQ_BREAK, /* No longer used */ |
| 65 | LHREQ_EVENTFD, /* + address, fd. */ |
| 66 | }; |
| 67 | |
| 68 | /* |
| 69 | * The alignment to use between consumer and producer parts of vring. |
| 70 | * x86 pagesize for historical reasons. |
| 71 | */ |
| 72 | #define LGUEST_VRING_ALIGN 4096 |
| 73 | #endif /* _LINUX_LGUEST_LAUNCHER */ |