backends/hostmem-memfd.c

   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 "sysemu/hostmem.h"
  15 #include "sysemu/sysemu.h"
  16 #include "qom/object_interfaces.h"
  17 #include "qemu/memfd.h"
  18 #include "qemu/module.h"
  19 #include "qapi/error.h"
  20 #include "qom/object.h"
  21
  22 #define TYPE_MEMORY_BACKEND_MEMFD "memory-backend-memfd"
  23
  24 typedef struct HostMemoryBackendMemfd HostMemoryBackendMemfd;
  25 DECLARE_INSTANCE_CHECKER(HostMemoryBackendMemfd, MEMORY_BACKEND_MEMFD,
  26                          TYPE_MEMORY_BACKEND_MEMFD)
  27
  28
  29 struct HostMemoryBackendMemfd {
  30     HostMemoryBackend parent_obj;
  31
  32     bool hugetlb;
  33     uint64_t hugetlbsize;
  34     bool seal;
  35 };
  36
  37 static void
  38 memfd_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
  39 {
  40     HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(backend);
  41     char *name;
  42     int fd;
  43
  44     if (!backend->size) {
  45         error_setg(errp, "can't create backend with size 0");
  46         return;
  47     }
  48
  49     fd = qemu_memfd_create(TYPE_MEMORY_BACKEND_MEMFD, backend->size,
  50                            m->hugetlb, m->hugetlbsize, m->seal ?
  51                            F_SEAL_GROW | F_SEAL_SHRINK | F_SEAL_SEAL : 0,
  52                            errp);
  53     if (fd == -1) {
  54         return;
  55     }
  56
  57     name = host_memory_backend_get_name(backend);
  58     memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend),
  59                                    name, backend->size,
  60                                    backend->share, fd, errp);
  61     g_free(name);
  62 }
  63
  64 static bool
  65 memfd_backend_get_hugetlb(Object *o, Error **errp)
  66 {
  67     return MEMORY_BACKEND_MEMFD(o)->hugetlb;
  68 }
  69
  70 static void
  71 memfd_backend_set_hugetlb(Object *o, bool value, Error **errp)
  72 {
  73     MEMORY_BACKEND_MEMFD(o)->hugetlb = value;
  74 }
  75
  76 static void
  77 memfd_backend_set_hugetlbsize(Object *obj, Visitor *v, const char *name,
  78                               void *opaque, Error **errp)
  79 {
  80     HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
  81     uint64_t value;
  82
  83     if (host_memory_backend_mr_inited(MEMORY_BACKEND(obj))) {
  84         error_setg(errp, "cannot change property value");
  85         return;
  86     }
  87
  88     if (!visit_type_size(v, name, &value, errp)) {
  89         return;
  90     }
  91     if (!value) {
  92         error_setg(errp, "Property '%s.%s' doesn't take value '%" PRIu64 "'",
  93                    object_get_typename(obj), name, value);
  94         return;
  95     }
  96     m->hugetlbsize = value;
  97 }
  98
  99 static void
 100 memfd_backend_get_hugetlbsize(Object *obj, Visitor *v, const char *name,
 101                               void *opaque, Error **errp)
 102 {
 103     HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
 104     uint64_t value = m->hugetlbsize;
 105
 106     visit_type_size(v, name, &value, errp);
 107 }
 108
 109 static bool
 110 memfd_backend_get_seal(Object *o, Error **errp)
 111 {
 112     return MEMORY_BACKEND_MEMFD(o)->seal;
 113 }
 114
 115 static void
 116 memfd_backend_set_seal(Object *o, bool value, Error **errp)
 117 {
 118     MEMORY_BACKEND_MEMFD(o)->seal = value;
 119 }
 120
 121 static void
 122 memfd_backend_instance_init(Object *obj)
 123 {
 124     HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
 125
 126     /* default to sealed file */
 127     m->seal = true;
 128     MEMORY_BACKEND(m)->share = true;
 129 }
 130
 131 static void
 132 memfd_backend_class_init(ObjectClass *oc, void *data)
 133 {
 134     HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
 135
 136     bc->alloc = memfd_backend_memory_alloc;
 137
 138     if (qemu_memfd_check(MFD_HUGETLB)) {
 139         object_class_property_add_bool(oc, "hugetlb",
 140                                        memfd_backend_get_hugetlb,
 141                                        memfd_backend_set_hugetlb);
 142         object_class_property_set_description(oc, "hugetlb",
 143                                               "Use huge pages");
 144         object_class_property_add(oc, "hugetlbsize", "int",
 145                                   memfd_backend_get_hugetlbsize,
 146                                   memfd_backend_set_hugetlbsize,
 147                                   NULL, NULL);
 148         object_class_property_set_description(oc, "hugetlbsize",
 149                                               "Huge pages size (ex: 2M, 1G)");
 150     }
 151     object_class_property_add_bool(oc, "seal",
 152                                    memfd_backend_get_seal,
 153                                    memfd_backend_set_seal);
 154     object_class_property_set_description(oc, "seal",
 155                                           "Seal growing & shrinking");
 156 }
 157
 158 static const TypeInfo memfd_backend_info = {
 159     .name = TYPE_MEMORY_BACKEND_MEMFD,
 160     .parent = TYPE_MEMORY_BACKEND,
 161     .instance_init = memfd_backend_instance_init,
 162     .class_init = memfd_backend_class_init,
 163     .instance_size = sizeof(HostMemoryBackendMemfd),
 164 };
 165
 166 static void register_types(void)
 167 {
 168     if (qemu_memfd_check(MFD_ALLOW_SEALING)) {
 169         type_register_static(&memfd_backend_info);
 170     }
 171 }
 172
 173 type_init(register_types);