Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
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linux
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
44static inline unsigned long
45hcall(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
62void 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
69struct 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. :*/
77struct 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};
114extern struct lguest_data lguest_data;
115#endif /* __ASSEMBLY__ */
116#endif /* _ASM_LGUEST_H */