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 #include "qemu/osdep.h"
  13 #include "qemu-common.h"
  14 #include "sysemu/hostmem.h"
  15 #include "sysemu/sysemu.h"
  16 #include "qom/object_interfaces.h"
  17 #include "qemu/memfd.h"
  18 #include "qapi/error.h"
  19
  20 #define TYPE_MEMORY_BACKEND_MEMFD "memory-backend-memfd"
  21
  22 #define MEMORY_BACKEND_MEMFD(obj)                                        \
  23     OBJECT_CHECK(HostMemoryBackendMemfd, (obj), TYPE_MEMORY_BACKEND_MEMFD)
  24
  25 typedef struct HostMemoryBackendMemfd HostMemoryBackendMemfd;
  26
  27 struct HostMemoryBackendMemfd {
  28     HostMemoryBackend parent_obj;
  29
  30     bool hugetlb;
  31     uint64_t hugetlbsize;
  32     bool seal;
  33 };
  34
  35 static void
  36 memfd_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
  37 {
  38     HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(backend);
  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     if (host_memory_backend_mr_inited(backend)) {
  48         return;
  49     }
  50
  51     backend->force_prealloc = mem_prealloc;
  52     fd = qemu_memfd_create(TYPE_MEMORY_BACKEND_MEMFD, backend->size,
  53                            m->hugetlb, m->hugetlbsize, m->seal ?
  54                            F_SEAL_GROW | F_SEAL_SHRINK | F_SEAL_SEAL : 0,
  55                            errp);
  56     if (fd == -1) {
  57         return;
  58     }
  59
  60     name = object_get_canonical_path(OBJECT(backend));
  61     memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend),
  62                                    name, backend->size, true, fd, errp);
  63     g_free(name);
  64 }
  65
  66 static bool
  67 memfd_backend_get_hugetlb(Object *o, Error **errp)
  68 {
  69     return MEMORY_BACKEND_MEMFD(o)->hugetlb;
  70 }
  71
  72 static void
  73 memfd_backend_set_hugetlb(Object *o, bool value, Error **errp)
  74 {
  75     MEMORY_BACKEND_MEMFD(o)->hugetlb = value;
  76 }
  77
  78 static void
  79 memfd_backend_set_hugetlbsize(Object *obj, Visitor *v, const char *name,
  80                               void *opaque, Error **errp)
  81 {
  82     HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
  83     Error *local_err = NULL;
  84     uint64_t value;
  85
  86     if (host_memory_backend_mr_inited(MEMORY_BACKEND(obj))) {
  87         error_setg(&local_err, "cannot change property value");
  88         goto out;
  89     }
  90
  91     visit_type_size(v, name, &value, &local_err);
  92     if (local_err) {
  93         goto out;
  94     }
  95     if (!value) {
  96         error_setg(&local_err, "Property '%s.%s' doesn't take value '%"
  97                    PRIu64 "'", object_get_typename(obj), name, value);
  98         goto out;
  99     }
 100     m->hugetlbsize = value;
 101 out:
 102     error_propagate(errp, local_err);
 103 }
 104
 105 static void
 106 memfd_backend_get_hugetlbsize(Object *obj, Visitor *v, const char *name,
 107                               void *opaque, Error **errp)
 108 {
 109     HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
 110     uint64_t value = m->hugetlbsize;
 111
 112     visit_type_size(v, name, &value, errp);
 113 }
 114
 115 static bool
 116 memfd_backend_get_seal(Object *o, Error **errp)
 117 {
 118     return MEMORY_BACKEND_MEMFD(o)->seal;
 119 }
 120
 121 static void
 122 memfd_backend_set_seal(Object *o, bool value, Error **errp)
 123 {
 124     MEMORY_BACKEND_MEMFD(o)->seal = value;
 125 }
 126
 127 static void
 128 memfd_backend_instance_init(Object *obj)
 129 {
 130     HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
 131
 132     /* default to sealed file */
 133     m->seal = true;
 134 }
 135
 136 static void
 137 memfd_backend_class_init(ObjectClass *oc, void *data)
 138 {
 139     HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
 140
 141     bc->alloc = memfd_backend_memory_alloc;
 142
 143     object_class_property_add_bool(oc, "hugetlb",
 144                                    memfd_backend_get_hugetlb,
 145                                    memfd_backend_set_hugetlb,
 146                                    &error_abort);
 147     object_class_property_add(oc, "hugetlbsize", "int",
 148                               memfd_backend_get_hugetlbsize,
 149                               memfd_backend_set_hugetlbsize,
 150                               NULL, NULL, &error_abort);
 151     object_class_property_add_bool(oc, "seal",
 152                                    memfd_backend_get_seal,
 153                                    memfd_backend_set_seal,
 154                                    &error_abort);
 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     type_register_static(&memfd_backend_info);
 168 }
 169
 170 type_init(register_types);