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
  21 #define TYPE_MEMORY_BACKEND_MEMFD "memory-backend-memfd"
  22
  23 #define MEMORY_BACKEND_MEMFD(obj)                                        \
  24     OBJECT_CHECK(HostMemoryBackendMemfd, (obj), TYPE_MEMORY_BACKEND_MEMFD)
  25
  26 typedef struct HostMemoryBackendMemfd HostMemoryBackendMemfd;
  27
  28 struct HostMemoryBackendMemfd {
  29     HostMemoryBackend parent_obj;
  30
  31     bool hugetlb;
  32     uint64_t hugetlbsize;
  33     bool seal;
  34 };
  35
  36 static void
  37 memfd_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
  38 {
  39     HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(backend);
  40     char *name;
  41     int fd;
  42
  43     if (!backend->size) {
  44         error_setg(errp, "can't create backend with size 0");
  45         return;
  46     }
  47
  48     fd = qemu_memfd_create(TYPE_MEMORY_BACKEND_MEMFD, backend->size,
  49                            m->hugetlb, m->hugetlbsize, m->seal ?
  50                            F_SEAL_GROW | F_SEAL_SHRINK | F_SEAL_SEAL : 0,
  51                            errp);
  52     if (fd == -1) {
  53         return;
  54     }
  55
  56     name = host_memory_backend_get_name(backend);
  57     memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend),
  58                                    name, backend->size,
  59                                    backend->share, fd, errp);
  60     g_free(name);
  61 }
  62
  63 static bool
  64 memfd_backend_get_hugetlb(Object *o, Error **errp)
  65 {
  66     return MEMORY_BACKEND_MEMFD(o)->hugetlb;
  67 }
  68
  69 static void
  70 memfd_backend_set_hugetlb(Object *o, bool value, Error **errp)
  71 {
  72     MEMORY_BACKEND_MEMFD(o)->hugetlb = value;
  73 }
  74
  75 static void
  76 memfd_backend_set_hugetlbsize(Object *obj, Visitor *v, const char *name,
  77                               void *opaque, Error **errp)
  78 {
  79     HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
  80     Error *local_err = NULL;
  81     uint64_t value;
  82
  83     if (host_memory_backend_mr_inited(MEMORY_BACKEND(obj))) {
  84         error_setg(&local_err, "cannot change property value");
  85         goto out;
  86     }
  87
  88     if (!visit_type_size(v, name, &value, &local_err)) {
  89         goto out;
  90     }
  91     if (!value) {
  92         error_setg(&local_err, "Property '%s.%s' doesn't take value '%"
  93                    PRIu64 "'", object_get_typename(obj), name, value);
  94         goto out;
  95     }
  96     m->hugetlbsize = value;
  97 out:
  98     error_propagate(errp, local_err);
  99 }
 100
 101 static void
 102 memfd_backend_get_hugetlbsize(Object *obj, Visitor *v, const char *name,
 103                               void *opaque, Error **errp)
 104 {
 105     HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
 106     uint64_t value = m->hugetlbsize;
 107
 108     visit_type_size(v, name, &value, errp);
 109 }
 110
 111 static bool
 112 memfd_backend_get_seal(Object *o, Error **errp)
 113 {
 114     return MEMORY_BACKEND_MEMFD(o)->seal;
 115 }
 116
 117 static void
 118 memfd_backend_set_seal(Object *o, bool value, Error **errp)
 119 {
 120     MEMORY_BACKEND_MEMFD(o)->seal = value;
 121 }
 122
 123 static void
 124 memfd_backend_instance_init(Object *obj)
 125 {
 126     HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
 127
 128     /* default to sealed file */
 129     m->seal = true;
 130     MEMORY_BACKEND(m)->share = true;
 131 }
 132
 133 static void
 134 memfd_backend_class_init(ObjectClass *oc, void *data)
 135 {
 136     HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
 137
 138     bc->alloc = memfd_backend_memory_alloc;
 139
 140     if (qemu_memfd_check(MFD_HUGETLB)) {
 141         object_class_property_add_bool(oc, "hugetlb",
 142                                        memfd_backend_get_hugetlb,
 143                                        memfd_backend_set_hugetlb);
 144         object_class_property_set_description(oc, "hugetlb",
 145                                               "Use huge pages");
 146         object_class_property_add(oc, "hugetlbsize", "int",
 147                                   memfd_backend_get_hugetlbsize,
 148                                   memfd_backend_set_hugetlbsize,
 149                                   NULL, NULL);
 150         object_class_property_set_description(oc, "hugetlbsize",
 151                                               "Huge pages size (ex: 2M, 1G)");
 152     }
 153     object_class_property_add_bool(oc, "seal",
 154                                    memfd_backend_get_seal,
 155                                    memfd_backend_set_seal);
 156     object_class_property_set_description(oc, "seal",
 157                                           "Seal growing & shrinking");
 158 }
 159
 160 static const TypeInfo memfd_backend_info = {
 161     .name = TYPE_MEMORY_BACKEND_MEMFD,
 162     .parent = TYPE_MEMORY_BACKEND,
 163     .instance_init = memfd_backend_instance_init,
 164     .class_init = memfd_backend_class_init,
 165     .instance_size = sizeof(HostMemoryBackendMemfd),
 166 };
 167
 168 static void register_types(void)
 169 {
 170     if (qemu_memfd_check(MFD_ALLOW_SEALING)) {
 171         type_register_static(&memfd_backend_info);
 172     }
 173 }
 174
 175 type_init(register_types);