include/linux/lguest.h

   1 /* Things the lguest guest needs to know.  Note: like all lguest interfaces,
   2  * this is subject to wild and random change between versions. */
   3 #ifndef _ASM_LGUEST_H
   4 #define _ASM_LGUEST_H
   5
   6 #ifndef __ASSEMBLY__
   7 #include <asm/irq.h>
   8
   9 #define LHCALL_FLUSH_ASYNC      0
  10 #define LHCALL_LGUEST_INIT      1
  11 #define LHCALL_CRASH            2
  12 #define LHCALL_LOAD_GDT         3
  13 #define LHCALL_NEW_PGTABLE      4
  14 #define LHCALL_FLUSH_TLB        5
  15 #define LHCALL_LOAD_IDT_ENTRY   6
  16 #define LHCALL_SET_STACK        7
  17 #define LHCALL_TS               8
  18 #define LHCALL_SET_CLOCKEVENT   9
  19 #define LHCALL_HALT             10
  20 #define LHCALL_GET_WALLCLOCK    11
  21 #define LHCALL_BIND_DMA         12
  22 #define LHCALL_SEND_DMA         13
  23 #define LHCALL_SET_PTE          14
  24 #define LHCALL_SET_PMD          15
  25 #define LHCALL_LOAD_TLS         16
  26
  27 #define LG_CLOCK_MIN_DELTA      100UL
  28 #define LG_CLOCK_MAX_DELTA      ULONG_MAX
  29
  30 /*G:031 First, how does our Guest contact the Host to ask for privileged
  31  * operations?  There are two ways: the direct way is to make a "hypercall",
  32  * to make requests of the Host Itself.
  33  *
  34  * Our hypercall mechanism uses the highest unused trap code (traps 32 and
  35  * above are used by real hardware interrupts).  Seventeen hypercalls are
  36  * available: the hypercall number is put in the %eax register, and the
  37  * arguments (when required) are placed in %edx, %ebx and %ecx.  If a return
  38  * value makes sense, it's returned in %eax.
  39  *
  40  * Grossly invalid calls result in Sudden Death at the hands of the vengeful
  41  * Host, rather than returning failure.  This reflects Winston Churchill's
  42  * definition of a gentleman: "someone who is only rude intentionally". */
  43 #define LGUEST_TRAP_ENTRY 0x1F
  44
  45 static inline unsigned long
  46 hcall(unsigned long call,
  47       unsigned long arg1, unsigned long arg2, unsigned long arg3)
  48 {
  49         /* "int" is the Intel instruction to trigger a trap. */
  50         asm volatile("int $" __stringify(LGUEST_TRAP_ENTRY)
  51                        /* The call is in %eax (aka "a"), and can be replaced */
  52                      : "=a"(call)
  53                        /* The other arguments are in %eax, %edx, %ebx & %ecx */
  54                      : "a"(call), "d"(arg1), "b"(arg2), "c"(arg3)
  55                        /* "memory" means this might write somewhere in memory.
  56                         * This isn't true for all calls, but it's safe to tell
  57                         * gcc that it might happen so it doesn't get clever. */
  58                      : "memory");
  59         return call;
  60 }
  61 /*:*/
  62
  63 void async_hcall(unsigned long call,
  64                  unsigned long arg1, unsigned long arg2, unsigned long arg3);
  65
  66 /* Can't use our min() macro here: needs to be a constant */
  67 #define LGUEST_IRQS (NR_IRQS < 32 ? NR_IRQS: 32)
  68
  69 #define LHCALL_RING_SIZE 64
  70 struct hcall_ring
  71 {
  72         u32 eax, edx, ebx, ecx;
  73 };
  74
  75 /*G:032 The second method of communicating with the Host is to via "struct
  76  * lguest_data".  The Guest's very first hypercall is to tell the Host where
  77  * this is, and then the Guest and Host both publish information in it. :*/
  78 struct lguest_data
  79 {
  80         /* 512 == enabled (same as eflags in normal hardware).  The Guest
  81          * changes interrupts so often that a hypercall is too slow. */
  82         unsigned int irq_enabled;
  83         /* Fine-grained interrupt disabling by the Guest */
  84         DECLARE_BITMAP(blocked_interrupts, LGUEST_IRQS);
  85
  86         /* The Host writes the virtual address of the last page fault here,
  87          * which saves the Guest a hypercall.  CR2 is the native register where
  88          * this address would normally be found. */
  89         unsigned long cr2;
  90
  91         /* Async hypercall ring.  Instead of directly making hypercalls, we can
  92          * place them in here for processing the next time the Host wants.
  93          * This batching can be quite efficient. */
  94
  95         /* 0xFF == done (set by Host), 0 == pending (set by Guest). */
  96         u8 hcall_status[LHCALL_RING_SIZE];
  97         /* The actual registers for the hypercalls. */
  98         struct hcall_ring hcalls[LHCALL_RING_SIZE];
  99
 100 /* Fields initialized by the Host at boot: */
 101         /* Memory not to try to access */
 102         unsigned long reserve_mem;
 103         /* ID of this Guest (used by network driver to set ethernet address) */
 104         u16 guestid;
 105         /* KHz for the TSC clock. */
 106         u32 tsc_khz;
 107
 108 /* Fields initialized by the Guest at boot: */
 109         /* Instruction range to suppress interrupts even if enabled */
 110         unsigned long noirq_start, noirq_end;
 111 };
 112 extern struct lguest_data lguest_data;
 113 #endif /* __ASSEMBLY__ */
 114 #endif  /* _ASM_LGUEST_H */