The new option can be used to indicate that the file contents can be destroyed and don't need to be flushed to disk when QEMU exits or when the memory backend object is removed. Internally, it will trigger a madvise(MADV_REMOVE) call when the memory backend is removed. Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> Message-Id: <20170824192315.5897-4-ehabkost@redhat.com> [ehabkost: fixup: improved documentation] Reviewed-by: Daniel P. Berrange <berrange@redhat.com> Tested-by: Zack Cornelius <zack.cornelius@kove.net> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
171 lines
4.6 KiB
C
171 lines
4.6 KiB
C
/*
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* QEMU Host Memory Backend for hugetlbfs
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*
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* Copyright (C) 2013-2014 Red Hat Inc
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*
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* Authors:
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* Paolo Bonzini <pbonzini@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*/
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#include "qemu/osdep.h"
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#include "qapi/error.h"
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#include "qemu-common.h"
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#include "sysemu/hostmem.h"
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#include "sysemu/sysemu.h"
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#include "qom/object_interfaces.h"
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/* hostmem-file.c */
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/**
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* @TYPE_MEMORY_BACKEND_FILE:
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* name of backend that uses mmap on a file descriptor
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*/
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#define TYPE_MEMORY_BACKEND_FILE "memory-backend-file"
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#define MEMORY_BACKEND_FILE(obj) \
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OBJECT_CHECK(HostMemoryBackendFile, (obj), TYPE_MEMORY_BACKEND_FILE)
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typedef struct HostMemoryBackendFile HostMemoryBackendFile;
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struct HostMemoryBackendFile {
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HostMemoryBackend parent_obj;
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bool share;
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bool discard_data;
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char *mem_path;
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};
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static void
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file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
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{
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HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(backend);
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if (!backend->size) {
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error_setg(errp, "can't create backend with size 0");
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return;
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}
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if (!fb->mem_path) {
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error_setg(errp, "mem-path property not set");
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return;
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}
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#ifndef CONFIG_LINUX
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error_setg(errp, "-mem-path not supported on this host");
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#else
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if (!host_memory_backend_mr_inited(backend)) {
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gchar *path;
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backend->force_prealloc = mem_prealloc;
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path = object_get_canonical_path(OBJECT(backend));
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memory_region_init_ram_from_file(&backend->mr, OBJECT(backend),
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path,
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backend->size, fb->share,
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fb->mem_path, errp);
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g_free(path);
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}
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#endif
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}
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static char *get_mem_path(Object *o, Error **errp)
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{
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HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
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return g_strdup(fb->mem_path);
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}
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static void set_mem_path(Object *o, const char *str, Error **errp)
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{
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HostMemoryBackend *backend = MEMORY_BACKEND(o);
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HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
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if (host_memory_backend_mr_inited(backend)) {
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error_setg(errp, "cannot change property value");
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return;
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}
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g_free(fb->mem_path);
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fb->mem_path = g_strdup(str);
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}
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static bool file_memory_backend_get_share(Object *o, Error **errp)
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{
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HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
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return fb->share;
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}
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static void file_memory_backend_set_share(Object *o, bool value, Error **errp)
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{
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HostMemoryBackend *backend = MEMORY_BACKEND(o);
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HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
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if (host_memory_backend_mr_inited(backend)) {
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error_setg(errp, "cannot change property value");
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return;
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}
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fb->share = value;
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}
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static bool file_memory_backend_get_discard_data(Object *o, Error **errp)
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{
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return MEMORY_BACKEND_FILE(o)->discard_data;
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}
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static void file_memory_backend_set_discard_data(Object *o, bool value,
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Error **errp)
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{
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MEMORY_BACKEND_FILE(o)->discard_data = value;
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}
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static void file_backend_unparent(Object *obj)
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{
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HostMemoryBackend *backend = MEMORY_BACKEND(obj);
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HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(obj);
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if (host_memory_backend_mr_inited(backend) && fb->discard_data) {
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void *ptr = memory_region_get_ram_ptr(&backend->mr);
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uint64_t sz = memory_region_size(&backend->mr);
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qemu_madvise(ptr, sz, QEMU_MADV_REMOVE);
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}
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}
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static void
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file_backend_class_init(ObjectClass *oc, void *data)
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{
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HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
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bc->alloc = file_backend_memory_alloc;
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oc->unparent = file_backend_unparent;
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object_class_property_add_bool(oc, "share",
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file_memory_backend_get_share, file_memory_backend_set_share,
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&error_abort);
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object_class_property_add_bool(oc, "discard-data",
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file_memory_backend_get_discard_data, file_memory_backend_set_discard_data,
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&error_abort);
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object_class_property_add_str(oc, "mem-path",
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get_mem_path, set_mem_path,
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&error_abort);
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}
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static void file_backend_instance_finalize(Object *o)
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{
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HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
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g_free(fb->mem_path);
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}
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static const TypeInfo file_backend_info = {
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.name = TYPE_MEMORY_BACKEND_FILE,
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.parent = TYPE_MEMORY_BACKEND,
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.class_init = file_backend_class_init,
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.instance_finalize = file_backend_instance_finalize,
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.instance_size = sizeof(HostMemoryBackendFile),
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};
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static void register_types(void)
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{
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type_register_static(&file_backend_info);
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}
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type_init(register_types);
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