ppc/pnv: Add support for POWER8+ LPC Controller
[qemu.git] / util / mmap-alloc.c
1 /*
2 * Support for RAM backed by mmaped host memory.
3 *
4 * Copyright (c) 2015 Red Hat, Inc.
5 *
6 * Authors:
7 * Michael S. Tsirkin <mst@redhat.com>
8 *
9 * This work is licensed under the terms of the GNU GPL, version 2 or
10 * later. See the COPYING file in the top-level directory.
11 */
12
13 #include "qemu/osdep.h"
14 #include "qemu/mmap-alloc.h"
15 #include "qemu/host-utils.h"
16
17 #define HUGETLBFS_MAGIC 0x958458f6
18
19 #ifdef CONFIG_LINUX
20 #include <sys/vfs.h>
21 #endif
22
23 size_t qemu_fd_getpagesize(int fd)
24 {
25 #ifdef CONFIG_LINUX
26 struct statfs fs;
27 int ret;
28
29 if (fd != -1) {
30 do {
31 ret = fstatfs(fd, &fs);
32 } while (ret != 0 && errno == EINTR);
33
34 if (ret == 0 && fs.f_type == HUGETLBFS_MAGIC) {
35 return fs.f_bsize;
36 }
37 }
38 #endif
39
40 return getpagesize();
41 }
42
43 size_t qemu_mempath_getpagesize(const char *mem_path)
44 {
45 #ifdef CONFIG_LINUX
46 struct statfs fs;
47 int ret;
48
49 do {
50 ret = statfs(mem_path, &fs);
51 } while (ret != 0 && errno == EINTR);
52
53 if (ret != 0) {
54 fprintf(stderr, "Couldn't statfs() memory path: %s\n",
55 strerror(errno));
56 exit(1);
57 }
58
59 if (fs.f_type == HUGETLBFS_MAGIC) {
60 /* It's hugepage, return the huge page size */
61 return fs.f_bsize;
62 }
63 #endif
64
65 return getpagesize();
66 }
67
68 void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared)
69 {
70 /*
71 * Note: this always allocates at least one extra page of virtual address
72 * space, even if size is already aligned.
73 */
74 size_t total = size + align;
75 #if defined(__powerpc64__) && defined(__linux__)
76 /* On ppc64 mappings in the same segment (aka slice) must share the same
77 * page size. Since we will be re-allocating part of this segment
78 * from the supplied fd, we should make sure to use the same page size, to
79 * this end we mmap the supplied fd. In this case, set MAP_NORESERVE to
80 * avoid allocating backing store memory.
81 * We do this unless we are using the system page size, in which case
82 * anonymous memory is OK.
83 */
84 int anonfd = fd == -1 || qemu_fd_getpagesize(fd) == getpagesize() ? -1 : fd;
85 int flags = anonfd == -1 ? MAP_ANONYMOUS : MAP_NORESERVE;
86 void *ptr = mmap(0, total, PROT_NONE, flags | MAP_PRIVATE, anonfd, 0);
87 #else
88 void *ptr = mmap(0, total, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
89 #endif
90 size_t offset;
91 void *ptr1;
92
93 if (ptr == MAP_FAILED) {
94 return MAP_FAILED;
95 }
96
97 assert(is_power_of_2(align));
98 /* Always align to host page size */
99 assert(align >= getpagesize());
100
101 offset = QEMU_ALIGN_UP((uintptr_t)ptr, align) - (uintptr_t)ptr;
102 ptr1 = mmap(ptr + offset, size, PROT_READ | PROT_WRITE,
103 MAP_FIXED |
104 (fd == -1 ? MAP_ANONYMOUS : 0) |
105 (shared ? MAP_SHARED : MAP_PRIVATE),
106 fd, 0);
107 if (ptr1 == MAP_FAILED) {
108 munmap(ptr, total);
109 return MAP_FAILED;
110 }
111
112 if (offset > 0) {
113 munmap(ptr, offset);
114 }
115
116 /*
117 * Leave a single PROT_NONE page allocated after the RAM block, to serve as
118 * a guard page guarding against potential buffer overflows.
119 */
120 total -= offset;
121 if (total > size + getpagesize()) {
122 munmap(ptr1 + size + getpagesize(), total - size - getpagesize());
123 }
124
125 return ptr1;
126 }
127
128 void qemu_ram_munmap(void *ptr, size_t size)
129 {
130 if (ptr) {
131 /* Unmap both the RAM block and the guard page */
132 munmap(ptr, size + getpagesize());
133 }
134 }