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     backend->force_prealloc = mem_prealloc;
  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     visit_type_size(v, name, &value, &local_err);
  89     if (local_err) {
  90         goto out;
  91     }
  92     if (!value) {
  93         error_setg(&local_err, "Property '%s.%s' doesn't take value '%"
  94                    PRIu64 "'", object_get_typename(obj), name, value);
  95         goto out;
  96     }
  97     m->hugetlbsize = value;
  98 out:
  99     error_propagate(errp, local_err);
 100 }
 101
 102 static void
 103 memfd_backend_get_hugetlbsize(Object *obj, Visitor *v, const char *name,
 104                               void *opaque, Error **errp)
 105 {
 106     HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
 107     uint64_t value = m->hugetlbsize;
 108
 109     visit_type_size(v, name, &value, errp);
 110 }
 111
 112 static bool
 113 memfd_backend_get_seal(Object *o, Error **errp)
 114 {
 115     return MEMORY_BACKEND_MEMFD(o)->seal;
 116 }
 117
 118 static void
 119 memfd_backend_set_seal(Object *o, bool value, Error **errp)
 120 {
 121     MEMORY_BACKEND_MEMFD(o)->seal = value;
 122 }
 123
 124 static void
 125 memfd_backend_instance_init(Object *obj)
 126 {
 127     HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
 128
 129     /* default to sealed file */
 130     m->seal = true;
 131     MEMORY_BACKEND(m)->share = true;
 132 }
 133
 134 static void
 135 memfd_backend_class_init(ObjectClass *oc, void *data)
 136 {
 137     HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
 138
 139     bc->alloc = memfd_backend_memory_alloc;
 140
 141     if (qemu_memfd_check(MFD_HUGETLB)) {
 142         object_class_property_add_bool(oc, "hugetlb",
 143                                        memfd_backend_get_hugetlb,
 144                                        memfd_backend_set_hugetlb,
 145                                        &error_abort);
 146         object_class_property_set_description(oc, "hugetlb",
 147                                               "Use huge pages",
 148                                               &error_abort);
 149         object_class_property_add(oc, "hugetlbsize", "int",
 150                                   memfd_backend_get_hugetlbsize,
 151                                   memfd_backend_set_hugetlbsize,
 152                                   NULL, NULL, &error_abort);
 153         object_class_property_set_description(oc, "hugetlbsize",
 154                                               "Huge pages size (ex: 2M, 1G)",
 155                                               &error_abort);
 156     }
 157     object_class_property_add_bool(oc, "seal",
 158                                    memfd_backend_get_seal,
 159                                    memfd_backend_set_seal,
 160                                    &error_abort);
 161     object_class_property_set_description(oc, "seal",
 162                                           "Seal growing & shrinking",
 163                                           &error_abort);
 164 }
 165
 166 static const TypeInfo memfd_backend_info = {
 167     .name = TYPE_MEMORY_BACKEND_MEMFD,
 168     .parent = TYPE_MEMORY_BACKEND,
 169     .instance_init = memfd_backend_instance_init,
 170     .class_init = memfd_backend_class_init,
 171     .instance_size = sizeof(HostMemoryBackendMemfd),
 172 };
 173
 174 static void register_types(void)
 175 {
 176     if (qemu_memfd_check(MFD_ALLOW_SEALING)) {
 177         type_register_static(&memfd_backend_info);
 178     }
 179 }
 180
 181 type_init(register_types);