1 /*
2 * This file and its contents are supplied under the terms of the
3 * Common Development and Distribution License ("CDDL"), version 1.0.
4 * You may only use this file in accordance with the terms of version
5 * 1.0 of the CDDL.
6 *
7 * A full copy of the text of the CDDL should have accompanied this
8 * source. A copy of the CDDL is also available via the Internet at
9 * http://www.illumos.org/license/CDDL.
10 */
11
12 /*
13 * Copyright 2022 Oxide Computer Company
14 */
15
16
17 #include <stdio.h>
18 #include <unistd.h>
19 #include <stropts.h>
20 #include <strings.h>
21 #include <signal.h>
22 #include <setjmp.h>
23 #include <libgen.h>
24
25 #include <sys/vmm.h>
26 #include <sys/vmm_dev.h>
27 #include <sys/mman.h>
28 #include <vmmapi.h>
29
30 #include "common.h"
31
32 /* Half of a leaf page table is 256 pages */
33 #define LOWER_SZ (256 * 4096)
34 #define UPPER_SZ LOWER_SZ
35 #define TOTAL_SZ (LOWER_SZ + UPPER_SZ)
36
37 #define LOWER_OFF 0
38 #define UPPER_OFF LOWER_SZ
39
40 enum test_memsegs {
41 MSEG_LOW = 0,
42 MSEG_HIGH = 1,
43 };
44
45 static sigjmp_buf segv_env;
46
47 void
sigsegv_handler(int sig)48 sigsegv_handler(int sig)
49 {
50 siglongjmp(segv_env, 1);
51 }
52
53
54 int
main(int argc,char * argv[])55 main(int argc, char *argv[])
56 {
57 struct vmctx *ctx;
58 int res, fd;
59 void *guest_mem;
60 const char *suite_name = basename(argv[0]);
61
62 ctx = create_test_vm(suite_name);
63 if (ctx == NULL) {
64 perror("could open test VM");
65 return (1);
66 }
67 fd = vm_get_device_fd(ctx);
68
69 res = alloc_memseg(ctx, MSEG_LOW, LOWER_SZ, "mseg_low");
70 if (res != 0) {
71 perror("could not alloc low memseg");
72 goto bail;
73 }
74 res = alloc_memseg(ctx, MSEG_HIGH, UPPER_SZ, "mseg_high");
75 if (res != 0) {
76 perror("could not alloc high memseg");
77 goto bail;
78 }
79
80
81 res = vm_mmap_memseg(ctx, LOWER_OFF, MSEG_LOW, 0, LOWER_SZ, PROT_ALL);
82 if (res != 0) {
83 perror("could not map low memseg");
84 goto bail;
85 }
86 res = vm_mmap_memseg(ctx, UPPER_OFF, MSEG_HIGH, 0, UPPER_SZ, PROT_ALL);
87 if (res != 0) {
88 perror("could not map high memseg");
89 goto bail;
90 }
91
92 guest_mem = mmap(NULL, TOTAL_SZ, PROT_READ | PROT_WRITE, MAP_SHARED,
93 fd, 0);
94 if (guest_mem == MAP_FAILED) {
95 perror("could not mmap guest memory");
96 goto bail;
97 }
98
99 /* Fill memory with 0xff */
100 for (uintptr_t gpa = 0; gpa < TOTAL_SZ; gpa++) {
101 uint8_t *ptr = guest_mem + gpa;
102 *ptr = 0xff;
103 }
104
105 /* Unmap the lower memseg */
106 res = vm_munmap_memseg(ctx, LOWER_OFF, LOWER_SZ);
107 if (guest_mem == NULL) {
108 perror("could not unmap lower memseg");
109 goto bail;
110 }
111
112 /* Confirm upper contents are still correct/accessible */
113 for (uintptr_t gpa = UPPER_OFF; gpa < UPPER_OFF + UPPER_SZ; gpa++) {
114 uint8_t *ptr = guest_mem + gpa;
115 if (*ptr != 0xff) {
116 (void) printf("invalid mem contents at GPA %lx: %x\n",
117 gpa, *ptr);
118 goto bail;
119 }
120 *ptr = 0xee;
121 }
122
123 /*
124 * Attempt to access the lower contents, which should result in an
125 * expected (and thus handled) SIGSEGV.
126 */
127 struct sigaction sa = {
128 .sa_handler = sigsegv_handler,
129 };
130 struct sigaction old_sa;
131 res = sigaction(SIGSEGV, &sa, &old_sa);
132 if (res != 0) {
133 perror("could not prep signal handling for bad access");
134 goto bail;
135 }
136
137 if (sigsetjmp(segv_env, 1) == 0) {
138 volatile uint8_t *ptr = guest_mem;
139
140 /*
141 * This access to the guest space should fail, since the memseg
142 * covering the lower part of the VM space has been unmapped.
143 */
144 uint8_t tmp = *ptr;
145
146 (void) printf("access to %p (%x) should have failed\n", tmp);
147 goto bail;
148 }
149
150 /*
151 * Unmap and remap the space so any cached entries are dropped for the
152 * portion we expect is still accessible.
153 */
154 res = munmap(guest_mem, TOTAL_SZ);
155 if (res != 0) {
156 perror("could not unmap lower memseg");
157 goto bail;
158 }
159 guest_mem = mmap(NULL, TOTAL_SZ, PROT_READ | PROT_WRITE, MAP_SHARED,
160 fd, 0);
161 if (guest_mem == MAP_FAILED) {
162 perror("could not re-mmap guest memory");
163 goto bail;
164 }
165
166 /* Check the upper portion for accessibility. */
167 if (sigsetjmp(segv_env, 1) == 0) {
168 volatile uint8_t *ptr = guest_mem + UPPER_OFF;
169
170 uint8_t tmp = *ptr;
171 if (tmp != 0xee) {
172 (void) printf("unexpected value at %p (%x)\n", ptr,
173 tmp);
174 goto bail;
175 }
176
177 res = sigaction(SIGSEGV, &old_sa, NULL);
178 if (res != 0) {
179 perror("could not restore SIGSEGV handler");
180 goto bail;
181 }
182 } else {
183 (void) printf("unexpected fault in upper mapping\n");
184 goto bail;
185 }
186
187
188 /* Unmap the upper memseg */
189 res = vm_munmap_memseg(ctx, UPPER_OFF, UPPER_SZ);
190 if (guest_mem == NULL) {
191 perror("could not unmap upper memseg");
192 goto bail;
193 }
194
195 /* mission accomplished */
196 (void) printf("%s\tPASS\n", suite_name);
197 vm_destroy(ctx);
198 return (0);
199
200 bail:
201 vm_destroy(ctx);
202 return (1);
203 }
204