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 "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
  21 #define TYPE_MEMORY_BACKEND_MEMFD "memory-backend-memfd"
  22
  23 OBJECT_DECLARE_SIMPLE_TYPE(HostMemoryBackendMemfd, MEMORY_BACKEND_MEMFD)
  24
  25
  26 struct HostMemoryBackendMemfd {
  27     HostMemoryBackend parent_obj;
  28
  29     bool hugetlb;
  30     uint64_t hugetlbsize;
  31     bool seal;
  32 };
  33
  34 static bool
  35 memfd_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
  36 {
  37     HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(backend);
  38     g_autofree char *name = NULL;
  39     uint32_t ram_flags;
  40     int fd;
  41
  42     if (!backend->size) {
  43         error_setg(errp, "can't create backend with size 0");
  44         return false;
  45     }
  46
  47     fd = qemu_memfd_create(TYPE_MEMORY_BACKEND_MEMFD, backend->size,
  48                            m->hugetlb, m->hugetlbsize, m->seal ?
  49                            F_SEAL_GROW | F_SEAL_SHRINK | F_SEAL_SEAL : 0,
  50                            errp);
  51     if (fd == -1) {
  52         return false;
  53     }
  54
  55     name = host_memory_backend_get_name(backend);
  56     ram_flags = backend->share ? RAM_SHARED : 0;
  57     ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
  58     return memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend), name,
  59                                           backend->size, ram_flags, fd, 0, errp);
  60 }
  61
  62 static bool
  63 memfd_backend_get_hugetlb(Object *o, Error **errp)
  64 {
  65     return MEMORY_BACKEND_MEMFD(o)->hugetlb;
  66 }
  67
  68 static void
  69 memfd_backend_set_hugetlb(Object *o, bool value, Error **errp)
  70 {
  71     MEMORY_BACKEND_MEMFD(o)->hugetlb = value;
  72 }
  73
  74 static void
  75 memfd_backend_set_hugetlbsize(Object *obj, Visitor *v, const char *name,
  76                               void *opaque, Error **errp)
  77 {
  78     HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
  79     uint64_t value;
  80
  81     if (host_memory_backend_mr_inited(MEMORY_BACKEND(obj))) {
  82         error_setg(errp, "cannot change property value");
  83         return;
  84     }
  85
  86     if (!visit_type_size(v, name, &value, errp)) {
  87         return;
  88     }
  89     if (!value) {
  90         error_setg(errp, "Property '%s.%s' doesn't take value '%" PRIu64 "'",
  91                    object_get_typename(obj), name, value);
  92         return;
  93     }
  94     m->hugetlbsize = value;
  95 }
  96
  97 static void
  98 memfd_backend_get_hugetlbsize(Object *obj, Visitor *v, const char *name,
  99                               void *opaque, Error **errp)
 100 {
 101     HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
 102     uint64_t value = m->hugetlbsize;
 103
 104     visit_type_size(v, name, &value, errp);
 105 }
 106
 107 static bool
 108 memfd_backend_get_seal(Object *o, Error **errp)
 109 {
 110     return MEMORY_BACKEND_MEMFD(o)->seal;
 111 }
 112
 113 static void
 114 memfd_backend_set_seal(Object *o, bool value, Error **errp)
 115 {
 116     MEMORY_BACKEND_MEMFD(o)->seal = value;
 117 }
 118
 119 static void
 120 memfd_backend_instance_init(Object *obj)
 121 {
 122     HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
 123
 124     /* default to sealed file */
 125     m->seal = true;
 126     MEMORY_BACKEND(m)->share = true;
 127 }
 128
 129 static void
 130 memfd_backend_class_init(ObjectClass *oc, void *data)
 131 {
 132     HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
 133
 134     bc->alloc = memfd_backend_memory_alloc;
 135
 136     if (qemu_memfd_check(MFD_HUGETLB)) {
 137         object_class_property_add_bool(oc, "hugetlb",
 138                                        memfd_backend_get_hugetlb,
 139                                        memfd_backend_set_hugetlb);
 140         object_class_property_set_description(oc, "hugetlb",
 141                                               "Use huge pages");
 142         object_class_property_add(oc, "hugetlbsize", "int",
 143                                   memfd_backend_get_hugetlbsize,
 144                                   memfd_backend_set_hugetlbsize,
 145                                   NULL, NULL);
 146         object_class_property_set_description(oc, "hugetlbsize",
 147                                               "Huge pages size (ex: 2M, 1G)");
 148     }
 149     object_class_property_add_bool(oc, "seal",
 150                                    memfd_backend_get_seal,
 151                                    memfd_backend_set_seal);
 152     object_class_property_set_description(oc, "seal",
 153                                           "Seal growing & shrinking");
 154 }
 155
 156 static const TypeInfo memfd_backend_info = {
 157     .name = TYPE_MEMORY_BACKEND_MEMFD,
 158     .parent = TYPE_MEMORY_BACKEND,
 159     .instance_init = memfd_backend_instance_init,
 160     .class_init = memfd_backend_class_init,
 161     .instance_size = sizeof(HostMemoryBackendMemfd),
 162 };
 163
 164 static void register_types(void)
 165 {
 166     if (qemu_memfd_check(MFD_ALLOW_SEALING)) {
 167         type_register_static(&memfd_backend_info);
 168     }
 169 }
 170
 171 type_init(register_types);