1
26
27#include <stdint.h>
28#include <stdlib.h>
29#include <stdio.h>
30#include <string.h>
31#include <setjmp.h>
32#include <signal.h>
33#include <unistd.h>
34#include <getopt.h>
35
36static void cpuid(uint32_t idx,
37 uint32_t *eax,
38 uint32_t *ebx,
39 uint32_t *ecx,
40 uint32_t *edx,
41 int pv_context)
42{
43 asm volatile (
44 "test %1,%1 ; jz 1f ; ud2a ; .ascii \"xen\" ; 1: cpuid"
45 : "=a" (*eax), "=b" (*ebx), "=c" (*ecx), "=d" (*edx)
46 : "0" (idx), "1" (pv_context) );
47}
48
49static int check_for_xen(int pv_context)
50{
51 uint32_t eax, ebx, ecx, edx;
52 char signature[13];
53 uint32_t base;
54
55 for ( base = 0x40000000; base < 0x40010000; base += 0x100 )
56 {
57 cpuid(base, &eax, &ebx, &ecx, &edx, pv_context);
58
59 *(uint32_t *)(signature + 0) = ebx;
60 *(uint32_t *)(signature + 4) = ecx;
61 *(uint32_t *)(signature + 8) = edx;
62 signature[12] = '\0';
63
64 if ( !strcmp(" XenVMMXenVMM", signature) && (eax >= (base + 2)) )
65 goto found;
66 }
67
68 return 0;
69
70 found:
71 cpuid(base + 1, &eax, &ebx, &ecx, &edx, pv_context);
72 return 1;
73}
74
75static jmp_buf sigill_jmp;
76void sigill_handler(int sig)
77{
78 longjmp(sigill_jmp, 1);
79}
80
81static void usage(void)
82{
83 printf("Usage: xen_detect [options]\n");
84 printf("Options:\n");
85 printf(" -h,
--
help Display this information\n");
86 printf(" -q,
--
quiet Quiesce normal informational output\n");
87 printf(" -P,
--
pv Exit status 1 if not running as PV guest\n");
88 printf(" -H,
--
hvm Exit status 1 if not running as HVM guest.\n");
89 printf(" -N,
--
none Exit status 1 if running on Xen (PV or HVM)\n");
90}
91
92int main(int argc, char **argv)
93{
94 enum { XEN_PV = 1, XEN_HVM = 2, XEN_NONE = 3 } detected = 0, expected = 0;
95 uint32_t version = 0;
96 int ch, quiet = 0;
97
98 const static char sopts[] = "hqPHN";
99 const static struct option lopts[] = {
100 { "help", 0, NULL, 'h' },
101 { "quiet", 0, NULL, 'q' },
102 { "pv", 0, NULL, 'P' },
103 { "hvm", 0, NULL, 'H' },
104 { "none", 0, NULL, 'N' },
105 { 0, 0, 0, 0}
106 };
107
108 while ( (ch = getopt_long(argc, argv, sopts, lopts, NULL)) != -1 )
109 {
110 switch ( ch )
111 {
112 case 'q':
113 quiet = 1;
114 break;
115 case 'P':
116 expected = XEN_PV;
117 break;
118 case 'H':
119 expected = XEN_HVM;
120 break;
121 case 'N':
122 expected = XEN_NONE;
123 break;
124 default:
125 usage();
126 exit(1);
127 }
128 }
129
130
131 detected = XEN_HVM;
132 if ( (version = check_for_xen(0)) != 0 )
133 goto out;
134
135
140 detected = XEN_PV;
141 if ( !setjmp(sigill_jmp)
142 && (signal(SIGILL, sigill_handler) != SIG_ERR)
143 && ((version = check_for_xen(1)) != 0) )
144 goto out;
145
146 detected = XEN_NONE;
147
148 out:
149 if ( quiet )
150 ;
151 else if ( detected
==
XEN_NONE )
152 printf("Not running on Xen.\n");
153 else
154 printf("Running in %s context on Xen v%d.%d.\n",
155 (detected
==
XEN_PV) ? "PV" : "HVM",
156 (uint16_t)(version >> 16), (uint16_t)version);
157
158 return expected && (expected != detected);
159}