qemu/backends/hostmem.c
Michal Privoznik 6bb613f081 hostmem: Honor multiple preferred nodes if possible
If a memory-backend is configured with mode
HOST_MEM_POLICY_PREFERRED then
host_memory_backend_memory_complete() calls mbind() as:

  mbind(..., MPOL_PREFERRED, nodemask, ...);

Here, 'nodemask' is a bitmap of host NUMA nodes and corresponds
to the .host-nodes attribute. Therefore, there can be multiple
nodes specified. However, the documentation to MPOL_PREFERRED
says:

  MPOL_PREFERRED
    This mode sets the preferred node for allocation. ...
    If nodemask specifies more than one node ID, the first node
    in the mask will be selected as the preferred node.

Therefore, only the first node is honored and the rest is
silently ignored. Well, with recent changes to the kernel and
numactl we can do better.

The Linux kernel added in v5.15 via commit cfcaa66f8032
("mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY")
support for MPOL_PREFERRED_MANY, which accepts multiple preferred
NUMA nodes instead.

Then, numa_has_preferred_many() API was introduced to numactl
(v2.0.15~26) allowing applications to query kernel support.

Wiring this all together, we can pass MPOL_PREFERRED_MANY to the
mbind() call instead and stop ignoring multiple nodes, silently.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Message-Id: <a0b4adce1af5bd2344c2218eb4a04b3ff7bcfdb4.1671097918.git.mprivozn@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
2022-12-28 14:59:55 +01:00

581 lines
18 KiB
C

/*
* QEMU Host Memory Backend
*
* Copyright (C) 2013-2014 Red Hat Inc
*
* Authors:
* Igor Mammedov <imammedo@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 "sysemu/hostmem.h"
#include "hw/boards.h"
#include "qapi/error.h"
#include "qapi/qapi-builtin-visit.h"
#include "qapi/visitor.h"
#include "qemu/config-file.h"
#include "qom/object_interfaces.h"
#include "qemu/mmap-alloc.h"
#include "qemu/madvise.h"
#ifdef CONFIG_NUMA
#include <numaif.h>
#include <numa.h>
QEMU_BUILD_BUG_ON(HOST_MEM_POLICY_DEFAULT != MPOL_DEFAULT);
/*
* HOST_MEM_POLICY_PREFERRED may either translate to MPOL_PREFERRED or
* MPOL_PREFERRED_MANY, see comments further below.
*/
QEMU_BUILD_BUG_ON(HOST_MEM_POLICY_PREFERRED != MPOL_PREFERRED);
QEMU_BUILD_BUG_ON(HOST_MEM_POLICY_BIND != MPOL_BIND);
QEMU_BUILD_BUG_ON(HOST_MEM_POLICY_INTERLEAVE != MPOL_INTERLEAVE);
#endif
char *
host_memory_backend_get_name(HostMemoryBackend *backend)
{
if (!backend->use_canonical_path) {
return g_strdup(object_get_canonical_path_component(OBJECT(backend)));
}
return object_get_canonical_path(OBJECT(backend));
}
static void
host_memory_backend_get_size(Object *obj, Visitor *v, const char *name,
void *opaque, Error **errp)
{
HostMemoryBackend *backend = MEMORY_BACKEND(obj);
uint64_t value = backend->size;
visit_type_size(v, name, &value, errp);
}
static void
host_memory_backend_set_size(Object *obj, Visitor *v, const char *name,
void *opaque, Error **errp)
{
HostMemoryBackend *backend = MEMORY_BACKEND(obj);
uint64_t value;
if (host_memory_backend_mr_inited(backend)) {
error_setg(errp, "cannot change property %s of %s ", name,
object_get_typename(obj));
return;
}
if (!visit_type_size(v, name, &value, errp)) {
return;
}
if (!value) {
error_setg(errp,
"property '%s' of %s doesn't take value '%" PRIu64 "'",
name, object_get_typename(obj), value);
return;
}
backend->size = value;
}
static void
host_memory_backend_get_host_nodes(Object *obj, Visitor *v, const char *name,
void *opaque, Error **errp)
{
HostMemoryBackend *backend = MEMORY_BACKEND(obj);
uint16List *host_nodes = NULL;
uint16List **tail = &host_nodes;
unsigned long value;
value = find_first_bit(backend->host_nodes, MAX_NODES);
if (value == MAX_NODES) {
goto ret;
}
QAPI_LIST_APPEND(tail, value);
do {
value = find_next_bit(backend->host_nodes, MAX_NODES, value + 1);
if (value == MAX_NODES) {
break;
}
QAPI_LIST_APPEND(tail, value);
} while (true);
ret:
visit_type_uint16List(v, name, &host_nodes, errp);
qapi_free_uint16List(host_nodes);
}
static void
host_memory_backend_set_host_nodes(Object *obj, Visitor *v, const char *name,
void *opaque, Error **errp)
{
#ifdef CONFIG_NUMA
HostMemoryBackend *backend = MEMORY_BACKEND(obj);
uint16List *l, *host_nodes = NULL;
visit_type_uint16List(v, name, &host_nodes, errp);
for (l = host_nodes; l; l = l->next) {
if (l->value >= MAX_NODES) {
error_setg(errp, "Invalid host-nodes value: %d", l->value);
goto out;
}
}
for (l = host_nodes; l; l = l->next) {
bitmap_set(backend->host_nodes, l->value, 1);
}
out:
qapi_free_uint16List(host_nodes);
#else
error_setg(errp, "NUMA node binding are not supported by this QEMU");
#endif
}
static int
host_memory_backend_get_policy(Object *obj, Error **errp G_GNUC_UNUSED)
{
HostMemoryBackend *backend = MEMORY_BACKEND(obj);
return backend->policy;
}
static void
host_memory_backend_set_policy(Object *obj, int policy, Error **errp)
{
HostMemoryBackend *backend = MEMORY_BACKEND(obj);
backend->policy = policy;
#ifndef CONFIG_NUMA
if (policy != HOST_MEM_POLICY_DEFAULT) {
error_setg(errp, "NUMA policies are not supported by this QEMU");
}
#endif
}
static bool host_memory_backend_get_merge(Object *obj, Error **errp)
{
HostMemoryBackend *backend = MEMORY_BACKEND(obj);
return backend->merge;
}
static void host_memory_backend_set_merge(Object *obj, bool value, Error **errp)
{
HostMemoryBackend *backend = MEMORY_BACKEND(obj);
if (!host_memory_backend_mr_inited(backend)) {
backend->merge = value;
return;
}
if (value != backend->merge) {
void *ptr = memory_region_get_ram_ptr(&backend->mr);
uint64_t sz = memory_region_size(&backend->mr);
qemu_madvise(ptr, sz,
value ? QEMU_MADV_MERGEABLE : QEMU_MADV_UNMERGEABLE);
backend->merge = value;
}
}
static bool host_memory_backend_get_dump(Object *obj, Error **errp)
{
HostMemoryBackend *backend = MEMORY_BACKEND(obj);
return backend->dump;
}
static void host_memory_backend_set_dump(Object *obj, bool value, Error **errp)
{
HostMemoryBackend *backend = MEMORY_BACKEND(obj);
if (!host_memory_backend_mr_inited(backend)) {
backend->dump = value;
return;
}
if (value != backend->dump) {
void *ptr = memory_region_get_ram_ptr(&backend->mr);
uint64_t sz = memory_region_size(&backend->mr);
qemu_madvise(ptr, sz,
value ? QEMU_MADV_DODUMP : QEMU_MADV_DONTDUMP);
backend->dump = value;
}
}
static bool host_memory_backend_get_prealloc(Object *obj, Error **errp)
{
HostMemoryBackend *backend = MEMORY_BACKEND(obj);
return backend->prealloc;
}
static void host_memory_backend_set_prealloc(Object *obj, bool value,
Error **errp)
{
Error *local_err = NULL;
HostMemoryBackend *backend = MEMORY_BACKEND(obj);
if (!backend->reserve && value) {
error_setg(errp, "'prealloc=on' and 'reserve=off' are incompatible");
return;
}
if (!host_memory_backend_mr_inited(backend)) {
backend->prealloc = value;
return;
}
if (value && !backend->prealloc) {
int fd = memory_region_get_fd(&backend->mr);
void *ptr = memory_region_get_ram_ptr(&backend->mr);
uint64_t sz = memory_region_size(&backend->mr);
qemu_prealloc_mem(fd, ptr, sz, backend->prealloc_threads,
backend->prealloc_context, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return;
}
backend->prealloc = true;
}
}
static void host_memory_backend_get_prealloc_threads(Object *obj, Visitor *v,
const char *name, void *opaque, Error **errp)
{
HostMemoryBackend *backend = MEMORY_BACKEND(obj);
visit_type_uint32(v, name, &backend->prealloc_threads, errp);
}
static void host_memory_backend_set_prealloc_threads(Object *obj, Visitor *v,
const char *name, void *opaque, Error **errp)
{
HostMemoryBackend *backend = MEMORY_BACKEND(obj);
uint32_t value;
if (!visit_type_uint32(v, name, &value, errp)) {
return;
}
if (value <= 0) {
error_setg(errp, "property '%s' of %s doesn't take value '%d'", name,
object_get_typename(obj), value);
return;
}
backend->prealloc_threads = value;
}
static void host_memory_backend_init(Object *obj)
{
HostMemoryBackend *backend = MEMORY_BACKEND(obj);
MachineState *machine = MACHINE(qdev_get_machine());
/* TODO: convert access to globals to compat properties */
backend->merge = machine_mem_merge(machine);
backend->dump = machine_dump_guest_core(machine);
backend->reserve = true;
backend->prealloc_threads = machine->smp.cpus;
}
static void host_memory_backend_post_init(Object *obj)
{
object_apply_compat_props(obj);
}
bool host_memory_backend_mr_inited(HostMemoryBackend *backend)
{
/*
* NOTE: We forbid zero-length memory backend, so here zero means
* "we haven't inited the backend memory region yet".
*/
return memory_region_size(&backend->mr) != 0;
}
MemoryRegion *host_memory_backend_get_memory(HostMemoryBackend *backend)
{
return host_memory_backend_mr_inited(backend) ? &backend->mr : NULL;
}
void host_memory_backend_set_mapped(HostMemoryBackend *backend, bool mapped)
{
backend->is_mapped = mapped;
}
bool host_memory_backend_is_mapped(HostMemoryBackend *backend)
{
return backend->is_mapped;
}
size_t host_memory_backend_pagesize(HostMemoryBackend *memdev)
{
size_t pagesize = qemu_ram_pagesize(memdev->mr.ram_block);
g_assert(pagesize >= qemu_real_host_page_size());
return pagesize;
}
static void
host_memory_backend_memory_complete(UserCreatable *uc, Error **errp)
{
HostMemoryBackend *backend = MEMORY_BACKEND(uc);
HostMemoryBackendClass *bc = MEMORY_BACKEND_GET_CLASS(uc);
Error *local_err = NULL;
void *ptr;
uint64_t sz;
if (bc->alloc) {
bc->alloc(backend, &local_err);
if (local_err) {
goto out;
}
ptr = memory_region_get_ram_ptr(&backend->mr);
sz = memory_region_size(&backend->mr);
if (backend->merge) {
qemu_madvise(ptr, sz, QEMU_MADV_MERGEABLE);
}
if (!backend->dump) {
qemu_madvise(ptr, sz, QEMU_MADV_DONTDUMP);
}
#ifdef CONFIG_NUMA
unsigned long lastbit = find_last_bit(backend->host_nodes, MAX_NODES);
/* lastbit == MAX_NODES means maxnode = 0 */
unsigned long maxnode = (lastbit + 1) % (MAX_NODES + 1);
/* ensure policy won't be ignored in case memory is preallocated
* before mbind(). note: MPOL_MF_STRICT is ignored on hugepages so
* this doesn't catch hugepage case. */
unsigned flags = MPOL_MF_STRICT | MPOL_MF_MOVE;
int mode = backend->policy;
/* check for invalid host-nodes and policies and give more verbose
* error messages than mbind(). */
if (maxnode && backend->policy == MPOL_DEFAULT) {
error_setg(errp, "host-nodes must be empty for policy default,"
" or you should explicitly specify a policy other"
" than default");
return;
} else if (maxnode == 0 && backend->policy != MPOL_DEFAULT) {
error_setg(errp, "host-nodes must be set for policy %s",
HostMemPolicy_str(backend->policy));
return;
}
/* We can have up to MAX_NODES nodes, but we need to pass maxnode+1
* as argument to mbind() due to an old Linux bug (feature?) which
* cuts off the last specified node. This means backend->host_nodes
* must have MAX_NODES+1 bits available.
*/
assert(sizeof(backend->host_nodes) >=
BITS_TO_LONGS(MAX_NODES + 1) * sizeof(unsigned long));
assert(maxnode <= MAX_NODES);
#ifdef HAVE_NUMA_HAS_PREFERRED_MANY
if (mode == MPOL_PREFERRED && numa_has_preferred_many() > 0) {
/*
* Replace with MPOL_PREFERRED_MANY otherwise the mbind() below
* silently picks the first node.
*/
mode = MPOL_PREFERRED_MANY;
}
#endif
if (maxnode &&
mbind(ptr, sz, mode, backend->host_nodes, maxnode + 1, flags)) {
if (backend->policy != MPOL_DEFAULT || errno != ENOSYS) {
error_setg_errno(errp, errno,
"cannot bind memory to host NUMA nodes");
return;
}
}
#endif
/* Preallocate memory after the NUMA policy has been instantiated.
* This is necessary to guarantee memory is allocated with
* specified NUMA policy in place.
*/
if (backend->prealloc) {
qemu_prealloc_mem(memory_region_get_fd(&backend->mr), ptr, sz,
backend->prealloc_threads,
backend->prealloc_context, &local_err);
if (local_err) {
goto out;
}
}
}
out:
error_propagate(errp, local_err);
}
static bool
host_memory_backend_can_be_deleted(UserCreatable *uc)
{
if (host_memory_backend_is_mapped(MEMORY_BACKEND(uc))) {
return false;
} else {
return true;
}
}
static bool host_memory_backend_get_share(Object *o, Error **errp)
{
HostMemoryBackend *backend = MEMORY_BACKEND(o);
return backend->share;
}
static void host_memory_backend_set_share(Object *o, bool value, Error **errp)
{
HostMemoryBackend *backend = MEMORY_BACKEND(o);
if (host_memory_backend_mr_inited(backend)) {
error_setg(errp, "cannot change property value");
return;
}
backend->share = value;
}
#ifdef CONFIG_LINUX
static bool host_memory_backend_get_reserve(Object *o, Error **errp)
{
HostMemoryBackend *backend = MEMORY_BACKEND(o);
return backend->reserve;
}
static void host_memory_backend_set_reserve(Object *o, bool value, Error **errp)
{
HostMemoryBackend *backend = MEMORY_BACKEND(o);
if (host_memory_backend_mr_inited(backend)) {
error_setg(errp, "cannot change property value");
return;
}
if (backend->prealloc && !value) {
error_setg(errp, "'prealloc=on' and 'reserve=off' are incompatible");
return;
}
backend->reserve = value;
}
#endif /* CONFIG_LINUX */
static bool
host_memory_backend_get_use_canonical_path(Object *obj, Error **errp)
{
HostMemoryBackend *backend = MEMORY_BACKEND(obj);
return backend->use_canonical_path;
}
static void
host_memory_backend_set_use_canonical_path(Object *obj, bool value,
Error **errp)
{
HostMemoryBackend *backend = MEMORY_BACKEND(obj);
backend->use_canonical_path = value;
}
static void
host_memory_backend_class_init(ObjectClass *oc, void *data)
{
UserCreatableClass *ucc = USER_CREATABLE_CLASS(oc);
ucc->complete = host_memory_backend_memory_complete;
ucc->can_be_deleted = host_memory_backend_can_be_deleted;
object_class_property_add_bool(oc, "merge",
host_memory_backend_get_merge,
host_memory_backend_set_merge);
object_class_property_set_description(oc, "merge",
"Mark memory as mergeable");
object_class_property_add_bool(oc, "dump",
host_memory_backend_get_dump,
host_memory_backend_set_dump);
object_class_property_set_description(oc, "dump",
"Set to 'off' to exclude from core dump");
object_class_property_add_bool(oc, "prealloc",
host_memory_backend_get_prealloc,
host_memory_backend_set_prealloc);
object_class_property_set_description(oc, "prealloc",
"Preallocate memory");
object_class_property_add(oc, "prealloc-threads", "int",
host_memory_backend_get_prealloc_threads,
host_memory_backend_set_prealloc_threads,
NULL, NULL);
object_class_property_set_description(oc, "prealloc-threads",
"Number of CPU threads to use for prealloc");
object_class_property_add_link(oc, "prealloc-context",
TYPE_THREAD_CONTEXT, offsetof(HostMemoryBackend, prealloc_context),
object_property_allow_set_link, OBJ_PROP_LINK_STRONG);
object_class_property_set_description(oc, "prealloc-context",
"Context to use for creating CPU threads for preallocation");
object_class_property_add(oc, "size", "int",
host_memory_backend_get_size,
host_memory_backend_set_size,
NULL, NULL);
object_class_property_set_description(oc, "size",
"Size of the memory region (ex: 500M)");
object_class_property_add(oc, "host-nodes", "int",
host_memory_backend_get_host_nodes,
host_memory_backend_set_host_nodes,
NULL, NULL);
object_class_property_set_description(oc, "host-nodes",
"Binds memory to the list of NUMA host nodes");
object_class_property_add_enum(oc, "policy", "HostMemPolicy",
&HostMemPolicy_lookup,
host_memory_backend_get_policy,
host_memory_backend_set_policy);
object_class_property_set_description(oc, "policy",
"Set the NUMA policy");
object_class_property_add_bool(oc, "share",
host_memory_backend_get_share, host_memory_backend_set_share);
object_class_property_set_description(oc, "share",
"Mark the memory as private to QEMU or shared");
#ifdef CONFIG_LINUX
object_class_property_add_bool(oc, "reserve",
host_memory_backend_get_reserve, host_memory_backend_set_reserve);
object_class_property_set_description(oc, "reserve",
"Reserve swap space (or huge pages) if applicable");
#endif /* CONFIG_LINUX */
/*
* Do not delete/rename option. This option must be considered stable
* (as if it didn't have the 'x-' prefix including deprecation period) as
* long as 4.0 and older machine types exists.
* Option will be used by upper layers to override (disable) canonical path
* for ramblock-id set by compat properties on old machine types ( <= 4.0),
* to keep migration working when backend is used for main RAM with
* -machine memory-backend= option (main RAM historically used prefix-less
* ramblock-id).
*/
object_class_property_add_bool(oc, "x-use-canonical-path-for-ramblock-id",
host_memory_backend_get_use_canonical_path,
host_memory_backend_set_use_canonical_path);
}
static const TypeInfo host_memory_backend_info = {
.name = TYPE_MEMORY_BACKEND,
.parent = TYPE_OBJECT,
.abstract = true,
.class_size = sizeof(HostMemoryBackendClass),
.class_init = host_memory_backend_class_init,
.instance_size = sizeof(HostMemoryBackend),
.instance_init = host_memory_backend_init,
.instance_post_init = host_memory_backend_post_init,
.interfaces = (InterfaceInfo[]) {
{ TYPE_USER_CREATABLE },
{ }
}
};
static void register_types(void)
{
type_register_static(&host_memory_backend_info);
}
type_init(register_types);