| 1 | /* |
| 2 | * QEMU host memfd memory backend |
| 3 | * |
| 4 | * Copyright (C) 2018 Red Hat Inc |
| 5 | * |
| 6 | * Authors: |
| 7 | * Marc-André Lureau <marcandre.lureau@redhat.com> |
| 8 | * |
| 9 | * This work is licensed under the terms of the GNU GPL, version 2 or later. |
| 10 | * See the COPYING file in the top-level directory. |
| 11 | */ |
| 12 | |
| 13 | #include "qemu/osdep.h" |
| 14 | #include "system/hostmem.h" |
| 15 | #include "qom/object_interfaces.h" |
| 16 | #include "qemu/memfd.h" |
| 17 | #include "qemu/module.h" |
| 18 | #include "qapi/error.h" |
| 19 | #include "qom/object.h" |
| 20 | #include "migration/cpr.h" |
| 21 | |
| 22 | OBJECT_DECLARE_SIMPLE_TYPE(HostMemoryBackendMemfd, MEMORY_BACKEND_MEMFD) |
| 23 | |
| 24 | |
| 25 | struct HostMemoryBackendMemfd { |
| 26 | HostMemoryBackend parent_obj; |
| 27 | |
| 28 | bool hugetlb; |
| 29 | uint64_t hugetlbsize; |
| 30 | bool seal; |
| 31 | }; |
| 32 | |
| 33 | static bool |
| 34 | memfd_backend_memory_alloc(HostMemoryBackend *backend, Error **errp) |
| 35 | { |
| 36 | HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(backend); |
| 37 | g_autofree char *name = host_memory_backend_get_name(backend); |
| 38 | int fd = cpr_find_fd(name, 0); |
| 39 | uint32_t ram_flags; |
| 40 | |
| 41 | if (!backend->size) { |
| 42 | error_setg(errp, "can't create backend with size 0"); |
| 43 | return false; |
| 44 | } |
| 45 | |
| 46 | if (fd >= 0) { |
| 47 | goto have_fd; |
| 48 | } |
| 49 | |
| 50 | fd = qemu_memfd_create(TYPE_MEMORY_BACKEND_MEMFD, backend->size, |
| 51 | m->hugetlb, m->hugetlbsize, m->seal ? |
| 52 | F_SEAL_GROW | F_SEAL_SHRINK | F_SEAL_SEAL : 0, |
| 53 | errp); |
| 54 | if (fd == -1) { |
| 55 | return false; |
| 56 | } |
| 57 | cpr_save_fd(name, 0, fd); |
| 58 | |
| 59 | have_fd: |
| 60 | backend->aligned = true; |
| 61 | ram_flags = backend->share ? RAM_SHARED : RAM_PRIVATE; |
| 62 | ram_flags |= backend->reserve ? 0 : RAM_NORESERVE; |
| 63 | ram_flags |= backend->guest_memfd ? RAM_GUEST_MEMFD : 0; |
| 64 | return memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend), name, |
| 65 | backend->size, ram_flags, fd, 0, errp); |
| 66 | } |
| 67 | |
| 68 | static bool |
| 69 | memfd_backend_get_hugetlb(Object *o, Error **errp) |
| 70 | { |
| 71 | return MEMORY_BACKEND_MEMFD(o)->hugetlb; |
| 72 | } |
| 73 | |
| 74 | static void |
| 75 | memfd_backend_set_hugetlb(Object *o, bool value, Error **errp) |
| 76 | { |
| 77 | MEMORY_BACKEND_MEMFD(o)->hugetlb = value; |
| 78 | } |
| 79 | |
| 80 | static void |
| 81 | memfd_backend_set_hugetlbsize(Object *obj, Visitor *v, const char *name, |
| 82 | void *opaque, Error **errp) |
| 83 | { |
| 84 | HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj); |
| 85 | uint64_t value; |
| 86 | |
| 87 | if (host_memory_backend_mr_inited(MEMORY_BACKEND(obj))) { |
| 88 | error_setg(errp, "cannot change property value"); |
| 89 | return; |
| 90 | } |
| 91 | |
| 92 | if (!visit_type_size(v, name, &value, errp)) { |
| 93 | return; |
| 94 | } |
| 95 | if (!value) { |
| 96 | error_setg(errp, "Property '%s.%s' doesn't take value '%" PRIu64 "'", |
| 97 | object_get_typename(obj), name, value); |
| 98 | return; |
| 99 | } |
| 100 | m->hugetlbsize = value; |
| 101 | } |
| 102 | |
| 103 | static void |
| 104 | memfd_backend_get_hugetlbsize(Object *obj, Visitor *v, const char *name, |
| 105 | void *opaque, Error **errp) |
| 106 | { |
| 107 | HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj); |
| 108 | uint64_t value = m->hugetlbsize; |
| 109 | |
| 110 | visit_type_size(v, name, &value, errp); |
| 111 | } |
| 112 | |
| 113 | static bool |
| 114 | memfd_backend_get_seal(Object *o, Error **errp) |
| 115 | { |
| 116 | return MEMORY_BACKEND_MEMFD(o)->seal; |
| 117 | } |
| 118 | |
| 119 | static void |
| 120 | memfd_backend_set_seal(Object *o, bool value, Error **errp) |
| 121 | { |
| 122 | MEMORY_BACKEND_MEMFD(o)->seal = value; |
| 123 | } |
| 124 | |
| 125 | static void |
| 126 | memfd_backend_instance_init(Object *obj) |
| 127 | { |
| 128 | HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj); |
| 129 | |
| 130 | /* default to sealed file */ |
| 131 | m->seal = true; |
| 132 | MEMORY_BACKEND(m)->share = true; |
| 133 | } |
| 134 | |
| 135 | static void |
| 136 | memfd_backend_class_init(ObjectClass *oc, const void *data) |
| 137 | { |
| 138 | HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc); |
| 139 | |
| 140 | bc->alloc = memfd_backend_memory_alloc; |
| 141 | |
| 142 | if (qemu_memfd_check(MFD_HUGETLB)) { |
| 143 | object_class_property_add_bool(oc, "hugetlb", |
| 144 | memfd_backend_get_hugetlb, |
| 145 | memfd_backend_set_hugetlb); |
| 146 | object_class_property_set_description(oc, "hugetlb", |
| 147 | "Use huge pages"); |
| 148 | object_class_property_add(oc, "hugetlbsize", "int", |
| 149 | memfd_backend_get_hugetlbsize, |
| 150 | memfd_backend_set_hugetlbsize, |
| 151 | NULL, NULL); |
| 152 | object_class_property_set_description(oc, "hugetlbsize", |
| 153 | "Huge pages size (ex: 2M, 1G)"); |
| 154 | } |
| 155 | object_class_property_add_bool(oc, "seal", |
| 156 | memfd_backend_get_seal, |
| 157 | memfd_backend_set_seal); |
| 158 | object_class_property_set_description(oc, "seal", |
| 159 | "Seal growing & shrinking"); |
| 160 | } |
| 161 | |
| 162 | static const TypeInfo memfd_backend_info = { |
| 163 | .name = TYPE_MEMORY_BACKEND_MEMFD, |
| 164 | .parent = TYPE_MEMORY_BACKEND, |
| 165 | .instance_init = memfd_backend_instance_init, |
| 166 | .class_init = memfd_backend_class_init, |
| 167 | .instance_size = sizeof(HostMemoryBackendMemfd), |
| 168 | }; |
| 169 | |
| 170 | static void register_types(void) |
| 171 | { |
| 172 | if (qemu_memfd_check(MFD_ALLOW_SEALING)) { |
| 173 | type_register_static(&memfd_backend_info); |
| 174 | } |
| 175 | } |
| 176 | |
| 177 | type_init(register_types); |