qemu/backends/hostmem-memfd.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

173 lines
4.9 KiB
C

/*
* QEMU host memfd memory backend
*
* Copyright (C) 2018 Red Hat Inc
*
* Authors:
* Marc-André Lureau <marcandre.lureau@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 "qom/object_interfaces.h"
#include "qemu/memfd.h"
#include "qemu/module.h"
#include "qapi/error.h"
#include "qom/object.h"
#define TYPE_MEMORY_BACKEND_MEMFD "memory-backend-memfd"
OBJECT_DECLARE_SIMPLE_TYPE(HostMemoryBackendMemfd, MEMORY_BACKEND_MEMFD)
struct HostMemoryBackendMemfd {
HostMemoryBackend parent_obj;
bool hugetlb;
uint64_t hugetlbsize;
bool seal;
};
static bool
memfd_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
{
HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(backend);
g_autofree char *name = NULL;
uint32_t ram_flags;
int fd;
if (!backend->size) {
error_setg(errp, "can't create backend with size 0");
return false;
}
fd = qemu_memfd_create(TYPE_MEMORY_BACKEND_MEMFD, backend->size,
m->hugetlb, m->hugetlbsize, m->seal ?
F_SEAL_GROW | F_SEAL_SHRINK | F_SEAL_SEAL : 0,
errp);
if (fd == -1) {
return false;
}
name = host_memory_backend_get_name(backend);
ram_flags = backend->share ? RAM_SHARED : 0;
ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
ram_flags |= backend->guest_memfd ? RAM_GUEST_MEMFD : 0;
return memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend), name,
backend->size, ram_flags, fd, 0, errp);
}
static bool
memfd_backend_get_hugetlb(Object *o, Error **errp)
{
return MEMORY_BACKEND_MEMFD(o)->hugetlb;
}
static void
memfd_backend_set_hugetlb(Object *o, bool value, Error **errp)
{
MEMORY_BACKEND_MEMFD(o)->hugetlb = value;
}
static void
memfd_backend_set_hugetlbsize(Object *obj, Visitor *v, const char *name,
void *opaque, Error **errp)
{
HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
uint64_t value;
if (host_memory_backend_mr_inited(MEMORY_BACKEND(obj))) {
error_setg(errp, "cannot change property value");
return;
}
if (!visit_type_size(v, name, &value, errp)) {
return;
}
if (!value) {
error_setg(errp, "Property '%s.%s' doesn't take value '%" PRIu64 "'",
object_get_typename(obj), name, value);
return;
}
m->hugetlbsize = value;
}
static void
memfd_backend_get_hugetlbsize(Object *obj, Visitor *v, const char *name,
void *opaque, Error **errp)
{
HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
uint64_t value = m->hugetlbsize;
visit_type_size(v, name, &value, errp);
}
static bool
memfd_backend_get_seal(Object *o, Error **errp)
{
return MEMORY_BACKEND_MEMFD(o)->seal;
}
static void
memfd_backend_set_seal(Object *o, bool value, Error **errp)
{
MEMORY_BACKEND_MEMFD(o)->seal = value;
}
static void
memfd_backend_instance_init(Object *obj)
{
HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(obj);
/* default to sealed file */
m->seal = true;
MEMORY_BACKEND(m)->share = true;
}
static void
memfd_backend_class_init(ObjectClass *oc, void *data)
{
HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
bc->alloc = memfd_backend_memory_alloc;
if (qemu_memfd_check(MFD_HUGETLB)) {
object_class_property_add_bool(oc, "hugetlb",
memfd_backend_get_hugetlb,
memfd_backend_set_hugetlb);
object_class_property_set_description(oc, "hugetlb",
"Use huge pages");
object_class_property_add(oc, "hugetlbsize", "int",
memfd_backend_get_hugetlbsize,
memfd_backend_set_hugetlbsize,
NULL, NULL);
object_class_property_set_description(oc, "hugetlbsize",
"Huge pages size (ex: 2M, 1G)");
}
object_class_property_add_bool(oc, "seal",
memfd_backend_get_seal,
memfd_backend_set_seal);
object_class_property_set_description(oc, "seal",
"Seal growing & shrinking");
}
static const TypeInfo memfd_backend_info = {
.name = TYPE_MEMORY_BACKEND_MEMFD,
.parent = TYPE_MEMORY_BACKEND,
.instance_init = memfd_backend_instance_init,
.class_init = memfd_backend_class_init,
.instance_size = sizeof(HostMemoryBackendMemfd),
};
static void register_types(void)
{
if (qemu_memfd_check(MFD_ALLOW_SEALING)) {
type_register_static(&memfd_backend_info);
}
}
type_init(register_types);