include/linux/lguest_launcher.h

   1 #ifndef _ASM_LGUEST_USER
   2 #define _ASM_LGUEST_USER
   3 /* Everything the "lguest" userspace program needs to know. */
   4 #include <linux/types.h>
   5 /* They can register up to 32 arrays of lguest_dma. */
   6 #define LGUEST_MAX_DMA          32
   7 /* At most we can dma 16 lguest_dma in one op. */
   8 #define LGUEST_MAX_DMA_SECTIONS 16
   9
  10 /* How many devices?  Assume each one wants up to two dma arrays per device. */
  11 #define LGUEST_MAX_DEVICES (LGUEST_MAX_DMA/2)
  12
  13 /*D:200
  14  * Lguest I/O
  15  *
  16  * The lguest I/O mechanism is the only way Guests can talk to devices.  There
  17  * are two hypercalls involved: SEND_DMA for output and BIND_DMA for input.  In
  18  * each case, "struct lguest_dma" describes the buffer: this contains 16
  19  * addr/len pairs, and if there are fewer buffer elements the len array is
  20  * terminated with a 0.
  21  *
  22  * I/O is organized by keys: BIND_DMA attaches buffers to a particular key, and
  23  * SEND_DMA transfers to buffers bound to particular key.  By convention, keys
  24  * correspond to a physical address within the device's page.  This means that
  25  * devices will never accidentally end up with the same keys, and allows the
  26  * Host use The Futex Trick (as we'll see later in our journey).
  27  *
  28  * SEND_DMA simply indicates a key to send to, and the physical address of the
  29  * "struct lguest_dma" to send.  The Host will write the number of bytes
  30  * transferred into the "struct lguest_dma"'s used_len member.
  31  *
  32  * BIND_DMA indicates a key to bind to, a pointer to an array of "struct
  33  * lguest_dma"s ready for receiving, the size of that array, and an interrupt
  34  * to trigger when data is received.  The Host will only allow transfers into
  35  * buffers with a used_len of zero: it then sets used_len to the number of
  36  * bytes transferred and triggers the interrupt for the Guest to process the
  37  * new input. */
  38 struct lguest_dma
  39 {
  40         /* 0 if free to be used, filled by the Host. */
  41         __u32 used_len;
  42         __u16 len[LGUEST_MAX_DMA_SECTIONS];
  43         unsigned long addr[LGUEST_MAX_DMA_SECTIONS];
  44 };
  45 /*:*/
  46
  47 /* Where the Host expects the Guest to SEND_DMA console output to. */
  48 #define LGUEST_CONSOLE_DMA_KEY 0
  49
  50 /*D:010
  51  * Drivers
  52  *
  53  * The Guest needs devices to do anything useful.  Since we don't let it touch
  54  * real devices (think of the damage it could do!) we provide virtual devices.
  55  * We could emulate a PCI bus with various devices on it, but that is a fairly
  56  * complex burden for the Host and suboptimal for the Guest, so we have our own
  57  * "lguest" bus and simple drivers.
  58  *
  59  * Devices are described by an array of LGUEST_MAX_DEVICES of these structs,
  60  * placed by the Launcher just above the top of physical memory:
  61  */
  62 struct lguest_device_desc {
  63         /* The device type: console, network, disk etc. */
  64         __u16 type;
  65 #define LGUEST_DEVICE_T_CONSOLE 1
  66 #define LGUEST_DEVICE_T_NET     2
  67 #define LGUEST_DEVICE_T_BLOCK   3
  68
  69         /* The specific features of this device: these depends on device type
  70          * except for LGUEST_DEVICE_F_RANDOMNESS. */
  71         __u16 features;
  72 #define LGUEST_NET_F_NOCSUM             0x4000 /* Don't bother checksumming */
  73 #define LGUEST_DEVICE_F_RANDOMNESS      0x8000 /* IRQ is fairly random */
  74
  75         /* This is how the Guest reports status of the device: the Host can set
  76          * LGUEST_DEVICE_S_REMOVED to indicate removal, but the rest are only
  77          * ever manipulated by the Guest, and only ever set. */
  78         __u16 status;
  79 /* 256 and above are device specific. */
  80 #define LGUEST_DEVICE_S_ACKNOWLEDGE     1 /* We have seen device. */
  81 #define LGUEST_DEVICE_S_DRIVER          2 /* We have found a driver */
  82 #define LGUEST_DEVICE_S_DRIVER_OK       4 /* Driver says OK! */
  83 #define LGUEST_DEVICE_S_REMOVED         8 /* Device has gone away. */
  84 #define LGUEST_DEVICE_S_REMOVED_ACK     16 /* Driver has been told. */
  85 #define LGUEST_DEVICE_S_FAILED          128 /* Something actually failed */
  86
  87         /* Each device exists somewhere in Guest physical memory, over some
  88          * number of pages. */
  89         __u16 num_pages;
  90         __u32 pfn;
  91 };
  92 /*:*/
  93
  94 /* Write command first word is a request. */
  95 enum lguest_req
  96 {
  97         LHREQ_INITIALIZE, /* + pfnlimit, pgdir, start, pageoffset */
  98         LHREQ_GETDMA, /* + addr (returns &lguest_dma, irq in ->used_len) */
  99         LHREQ_IRQ, /* + irq */
 100         LHREQ_BREAK, /* + on/off flag (on blocks until someone does off) */
 101 };
 102 #endif /* _ASM_LGUEST_USER */