qemu/backends/hostmem.c
Xiaoyao Li 37662d85b0 HostMem: Add mechanism to opt in kvm guest memfd via MachineState
Add a new member "guest_memfd" to memory backends. When it's set
to true, it enables RAM_GUEST_MEMFD in ram_flags, thus private kvm
guest_memfd will be allocated during RAMBlock allocation.

Memory backend's @guest_memfd is wired with @require_guest_memfd
field of MachineState. It avoid looking up the machine in phymem.c.

MachineState::require_guest_memfd is supposed to be set by any VMs
that requires KVM guest memfd as private memory, e.g., TDX VM.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Message-ID: <20240320083945.991426-8-michael.roth@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2024-04-23 17:35:25 +02:00

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"
#include "hw/qdev-core.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)
{
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);
if (!qemu_prealloc_mem(fd, ptr, sz, backend->prealloc_threads,
backend->prealloc_context, false, errp)) {
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->guest_memfd = machine_require_guest_memfd(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);
void *ptr;
uint64_t sz;
bool async = !phase_check(PHASE_LATE_BACKENDS_CREATED);
if (!bc->alloc) {
return;
}
if (!bc->alloc(backend, errp)) {
return;
}
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,
async, errp)) {
return;
}
}
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);