qemu/backends/hostmem-file.c
Marcel Apfelbaum 06329ccecf mem: add share parameter to memory-backend-ram
Currently only file backed memory backend can
be created with a "share" flag in order to allow
sharing guest RAM with other processes in the host.

Add the "share" flag also to RAM Memory Backend
in order to allow remapping parts of the guest RAM
to different host virtual addresses. This is needed
by the RDMA devices in order to remap non-contiguous
QEMU virtual addresses to a contiguous virtual address range.

Moved the "share" flag to the Host Memory base class,
modified phys_mem_alloc to include the new parameter
and a new interface memory_region_init_ram_shared_nomigrate.

There are no functional changes if the new flag is not used.

Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Marcel Apfelbaum <marcel@redhat.com>
2018-02-19 13:03:24 +02:00

187 lines
5.1 KiB
C

/*
* QEMU Host Memory Backend for hugetlbfs
*
* Copyright (C) 2013-2014 Red Hat Inc
*
* Authors:
* Paolo Bonzini <pbonzini@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "qemu-common.h"
#include "sysemu/hostmem.h"
#include "sysemu/sysemu.h"
#include "qom/object_interfaces.h"
/* hostmem-file.c */
/**
* @TYPE_MEMORY_BACKEND_FILE:
* name of backend that uses mmap on a file descriptor
*/
#define TYPE_MEMORY_BACKEND_FILE "memory-backend-file"
#define MEMORY_BACKEND_FILE(obj) \
OBJECT_CHECK(HostMemoryBackendFile, (obj), TYPE_MEMORY_BACKEND_FILE)
typedef struct HostMemoryBackendFile HostMemoryBackendFile;
struct HostMemoryBackendFile {
HostMemoryBackend parent_obj;
bool discard_data;
char *mem_path;
uint64_t align;
};
static void
file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
{
HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(backend);
if (!backend->size) {
error_setg(errp, "can't create backend with size 0");
return;
}
if (!fb->mem_path) {
error_setg(errp, "mem-path property not set");
return;
}
#ifndef CONFIG_LINUX
error_setg(errp, "-mem-path not supported on this host");
#else
if (!host_memory_backend_mr_inited(backend)) {
gchar *path;
backend->force_prealloc = mem_prealloc;
path = object_get_canonical_path(OBJECT(backend));
memory_region_init_ram_from_file(&backend->mr, OBJECT(backend),
path,
backend->size, fb->align, backend->share,
fb->mem_path, errp);
g_free(path);
}
#endif
}
static char *get_mem_path(Object *o, Error **errp)
{
HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
return g_strdup(fb->mem_path);
}
static void set_mem_path(Object *o, const char *str, Error **errp)
{
HostMemoryBackend *backend = MEMORY_BACKEND(o);
HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
if (host_memory_backend_mr_inited(backend)) {
error_setg(errp, "cannot change property value");
return;
}
g_free(fb->mem_path);
fb->mem_path = g_strdup(str);
}
static bool file_memory_backend_get_discard_data(Object *o, Error **errp)
{
return MEMORY_BACKEND_FILE(o)->discard_data;
}
static void file_memory_backend_set_discard_data(Object *o, bool value,
Error **errp)
{
MEMORY_BACKEND_FILE(o)->discard_data = value;
}
static void file_memory_backend_get_align(Object *o, Visitor *v,
const char *name, void *opaque,
Error **errp)
{
HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
uint64_t val = fb->align;
visit_type_size(v, name, &val, errp);
}
static void file_memory_backend_set_align(Object *o, Visitor *v,
const char *name, void *opaque,
Error **errp)
{
HostMemoryBackend *backend = MEMORY_BACKEND(o);
HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
Error *local_err = NULL;
uint64_t val;
if (host_memory_backend_mr_inited(backend)) {
error_setg(&local_err, "cannot change property value");
goto out;
}
visit_type_size(v, name, &val, &local_err);
if (local_err) {
goto out;
}
fb->align = val;
out:
error_propagate(errp, local_err);
}
static void file_backend_unparent(Object *obj)
{
HostMemoryBackend *backend = MEMORY_BACKEND(obj);
HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(obj);
if (host_memory_backend_mr_inited(backend) && fb->discard_data) {
void *ptr = memory_region_get_ram_ptr(&backend->mr);
uint64_t sz = memory_region_size(&backend->mr);
qemu_madvise(ptr, sz, QEMU_MADV_REMOVE);
}
}
static void
file_backend_class_init(ObjectClass *oc, void *data)
{
HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
bc->alloc = file_backend_memory_alloc;
oc->unparent = file_backend_unparent;
object_class_property_add_bool(oc, "discard-data",
file_memory_backend_get_discard_data, file_memory_backend_set_discard_data,
&error_abort);
object_class_property_add_str(oc, "mem-path",
get_mem_path, set_mem_path,
&error_abort);
object_class_property_add(oc, "align", "int",
file_memory_backend_get_align,
file_memory_backend_set_align,
NULL, NULL, &error_abort);
}
static void file_backend_instance_finalize(Object *o)
{
HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
g_free(fb->mem_path);
}
static const TypeInfo file_backend_info = {
.name = TYPE_MEMORY_BACKEND_FILE,
.parent = TYPE_MEMORY_BACKEND,
.class_init = file_backend_class_init,
.instance_finalize = file_backend_instance_finalize,
.instance_size = sizeof(HostMemoryBackendFile),
};
static void register_types(void)
{
type_register_static(&file_backend_info);
}
type_init(register_types);