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     ram_flags |= backend->guest_memfd ? RAM_GUEST_MEMFD : 0;
  59     return memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend), name,
  60                                           backend->size, ram_flags, fd, 0, errp);
  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     uint64_t value;
  81
  82     if (host_memory_backend_mr_inited(MEMORY_BACKEND(obj))) {
  83         error_setg(errp, "cannot change property value");
  84         return;
  85     }
  86
  87     if (!visit_type_size(v, name, &value, errp)) {
  88         return;
  89     }
  90     if (!value) {
  91         error_setg(errp, "Property '%s.%s' doesn't take value '%" PRIu64 "'",
  92                    object_get_typename(obj), name, value);
  93         return;
  94     }
  95     m->hugetlbsize = value;
  96 }
  97
  98 static void
  99 memfd_backend_get_hugetlbsize(Object *obj, Visitor *v, const char *name,
 100                               void *opaque, Error **errp)
 101 {
 102     HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
 103     uint64_t value = m->hugetlbsize;
 104
 105     visit_type_size(v, name, &value, errp);
 106 }
 107
 108 static bool
 109 memfd_backend_get_seal(Object *o, Error **errp)
 110 {
 111     return MEMORY_BACKEND_MEMFD(o)->seal;
 112 }
 113
 114 static void
 115 memfd_backend_set_seal(Object *o, bool value, Error **errp)
 116 {
 117     MEMORY_BACKEND_MEMFD(o)->seal = value;
 118 }
 119
 120 static void
 121 memfd_backend_instance_init(Object *obj)
 122 {
 123     HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
 124
 125     /* default to sealed file */
 126     m->seal = true;
 127     MEMORY_BACKEND(m)->share = true;
 128 }
 129
 130 static void
 131 memfd_backend_class_init(ObjectClass *oc, void *data)
 132 {
 133     HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
 134
 135     bc->alloc = memfd_backend_memory_alloc;
 136
 137     if (qemu_memfd_check(MFD_HUGETLB)) {
 138         object_class_property_add_bool(oc, "hugetlb",
 139                                        memfd_backend_get_hugetlb,
 140                                        memfd_backend_set_hugetlb);
 141         object_class_property_set_description(oc, "hugetlb",
 142                                               "Use huge pages");
 143         object_class_property_add(oc, "hugetlbsize", "int",
 144                                   memfd_backend_get_hugetlbsize,
 145                                   memfd_backend_set_hugetlbsize,
 146                                   NULL, NULL);
 147         object_class_property_set_description(oc, "hugetlbsize",
 148                                               "Huge pages size (ex: 2M, 1G)");
 149     }
 150     object_class_property_add_bool(oc, "seal",
 151                                    memfd_backend_get_seal,
 152                                    memfd_backend_set_seal);
 153     object_class_property_set_description(oc, "seal",
 154                                           "Seal growing & shrinking");
 155 }
 156
 157 static const TypeInfo memfd_backend_info = {
 158     .name = TYPE_MEMORY_BACKEND_MEMFD,
 159     .parent = TYPE_MEMORY_BACKEND,
 160     .instance_init = memfd_backend_instance_init,
 161     .class_init = memfd_backend_class_init,
 162     .instance_size = sizeof(HostMemoryBackendMemfd),
 163 };
 164
 165 static void register_types(void)
 166 {
 167     if (qemu_memfd_check(MFD_ALLOW_SEALING)) {
 168         type_register_static(&memfd_backend_info);
 169     }
 170 }
 171
 172 type_init(register_types);