LXR qemu/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
  23OBJECT_DECLARE_SIMPLE_TYPE(HostMemoryBackendMemfd, MEMORY_BACKEND_MEMFD)
  24
  25
  26struct HostMemoryBackendMemfd {
  27    HostMemoryBackend parent_obj;
  28
  29    bool hugetlb;
  30    uint64_t hugetlbsize;
  31    bool seal;
  32};
  33
  34static void
  35memfd_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
  36{
  37    HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(backend);
  38    uint32_t ram_flags;
  39    char *name;
  40    int fd;
  41
  42    if (!backend->size) {
  43        error_setg(errp, "can't create backend with size 0");
  44        return;
  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;
  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    memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend), name,
  59                                   backend->size, ram_flags, fd, 0, errp);
  60    g_free(name);
  61}
  62
  63static bool
  64memfd_backend_get_hugetlb(Object *o, Error **errp)
  65{
  66    return MEMORY_BACKEND_MEMFD(o)->hugetlb;
  67}
  68
  69static void
  70memfd_backend_set_hugetlb(Object *o, bool value, Error **errp)
  71{
  72    MEMORY_BACKEND_MEMFD(o)->hugetlb = value;
  73}
  74
  75static void
  76memfd_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
  98static void
  99memfd_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
 108static bool
 109memfd_backend_get_seal(Object *o, Error **errp)
 110{
 111    return MEMORY_BACKEND_MEMFD(o)->seal;
 112}
 113
 114static void
 115memfd_backend_set_seal(Object *o, bool value, Error **errp)
 116{
 117    MEMORY_BACKEND_MEMFD(o)->seal = value;
 118}
 119
 120static void
 121memfd_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
 130static void
 131memfd_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
 157static 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
 165static void register_types(void)
 166{
 167    if (qemu_memfd_check(MFD_ALLOW_SEALING)) {
 168        type_register_static(&memfd_backend_info);
 169    }
 170}
 171
 172type_init(register_types);
 173