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