> On 18. Feb 2026, at 02:51, Alexander Graf <[email protected]> wrote:
>
> Add a machine model to spawn a Nitro Enclave. Unlike the existing -M
> nitro-enclave, this machine model works exclusively with the -accel
> nitro accelerator to drive real Nitro Enclave creation. It supports
> memory allocation, number of CPU selection, both x86_64 as well as
> aarch64, implements the Enclave heartbeat logic and debug serial
> console.
>
> To use it, create an EIF file and run
>
> $ qemu-system-x86_64 -accel nitro,debug-mode=on -M nitro -nographic \
> -kernel test.eif
>
> or
>
> $ qemu-system-aarch64 -accel nitro,debug-mode=on -M nitro -nographic \
> -kernel test.eif
>
> Signed-off-by: Alexander Graf <[email protected]>
Hi,
The separation between -M nitro and -M nitro-enclave looks potentially confusing
to users. Could it potentially make sense to share the name or is that an
option not
on the cards?
-M nitro as a name is a bit ambiguous both in the short and long run
> ---
> hw/nitro/Kconfig | 7 ++
> hw/nitro/machine.c | 180 +++++++++++++++++++++++++++++++++++++
> hw/nitro/meson.build | 1 +
> include/hw/nitro/machine.h | 20 +++++
> 4 files changed, 208 insertions(+)
> create mode 100644 hw/nitro/machine.c
> create mode 100644 include/hw/nitro/machine.h
>
> diff --git a/hw/nitro/Kconfig b/hw/nitro/Kconfig
> index 6fe050d35d..910068c23c 100644
> --- a/hw/nitro/Kconfig
> +++ b/hw/nitro/Kconfig
> @@ -5,3 +5,10 @@ config NITRO_SERIAL_VSOCK
> config NITRO_HEARTBEAT
> bool
> depends on NITRO
> +
> +config NITRO_MACHINE
> + bool
> + default y
> + depends on NITRO
> + select NITRO_HEARTBEAT
> + select NITRO_SERIAL_VSOCK
> diff --git a/hw/nitro/machine.c b/hw/nitro/machine.c
> new file mode 100644
> index 0000000000..197adfbdb5
> --- /dev/null
> +++ b/hw/nitro/machine.c
> @@ -0,0 +1,180 @@
> +/*
> + * Nitro Enclaves (accel) machine
> + *
> + * Copyright © 2026 Amazon.com, Inc. or its affiliates. All Rights Reserved.
> + *
> + * Authors:
> + * Alexander Graf <[email protected]>
> + *
> + * Nitro Enclaves machine model for -accel nitro. This machine behaves
> + * like the nitro-enclave machine, but uses the real Nitro Enclaves
> + * backend to launch the virtual machine. It requires use of the -accel
> + * nitro.
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qemu/error-report.h"
> +#include "qapi/error.h"
> +#include "qom/object_interfaces.h"
> +#include "chardev/char.h"
> +#include "hw/core/boards.h"
> +#include "hw/core/cpu.h"
> +#include "hw/core/sysbus.h"
> +#include "hw/core/qdev-properties-system.h"
> +#include "hw/nitro/heartbeat.h"
> +#include "hw/nitro/machine.h"
> +#include "hw/nitro/serial-vsock.h"
> +#include "system/address-spaces.h"
> +#include "system/hostmem.h"
> +#include "system/system.h"
> +#include "system/nitro-accel.h"
> +#include "qemu/accel.h"
> +#include "hw/arm/machines-qom.h"
> +
> +#define EIF_LOAD_ADDR (8 * 1024 * 1024)
> +
> +static void nitro_create_cpu(const char *cpu_type, int index)
> +{
> + Object *obj = object_new(cpu_type);
> +
> + /* x86 CPUs require an apic-id before realize */
> + if (object_property_find(obj, "apic-id")) {
> + object_property_set_int(obj, "apic-id", index, &error_fatal);
> + }
> +
> + qdev_realize(DEVICE(obj), NULL, &error_fatal);
> +}
> +
> +static void nitro_machine_init(MachineState *machine)
> +{
> + const char *eif_path = machine->kernel_filename;
> + const char *cpu_type = machine->cpu_type;
> + g_autofree char *eif_data = NULL;
> + gsize eif_size;
> + int i;
> +
> + if (!nitro_enabled()) {
> + error_report("The 'nitro' machine requires -accel nitro");
> + exit(1);
> + }
> +
> + if (!cpu_type) {
> + ObjectClass *oc = cpu_class_by_name(target_cpu_type(), "host");
> +
> + if (!oc) {
> + error_report("nitro: no 'host' CPU available");
> + exit(1);
> + }
> + cpu_type = object_class_get_name(oc);
> + }
> +
> + if (!eif_path) {
> + error_report("nitro: -kernel <eif-file> is required");
> + exit(1);
> + }
> +
> + /* Expose memory as normal QEMU RAM. Needs to be huge page backed. */
> + memory_region_add_subregion(get_system_memory(), 0, machine->ram);
> +
> + /*
> + * Load EIF (-kernel) as raw blob at the EIF_LOAD_ADDR into guest RAM.
> + * The Nitro Hypervisor will extract its contents and bootstrap the
> + * Enclave from it.
> + */
> + if (!g_file_get_contents(eif_path, &eif_data, &eif_size, NULL)) {
> + error_report("nitro: failed to read EIF '%s'", eif_path);
> + exit(1);
> + }
> + address_space_write(&address_space_memory, EIF_LOAD_ADDR,
> + MEMTXATTRS_UNSPECIFIED, eif_data, eif_size);
> +
> + /* Nitro Enclaves require a heartbeat device. Provide one. */
> + sysbus_realize_and_unref(SYS_BUS_DEVICE(qdev_new(TYPE_NITRO_HEARTBEAT)),
> + &error_fatal);
> +
> + /*
> + * In debug mode, Nitro Enclaves expose the guest's serial output via
> + * vsock. When the accel is in debug mode, wire the vsock serial to
> + * the machine's serial port so that -nographic automatically works
> + */
> + if (object_property_get_bool(OBJECT(current_accel()), "debug-mode",
> NULL)) {
> + Chardev *chr = serial_hd(0);
> +
> + if (chr) {
> + DeviceState *dev = qdev_new(TYPE_NITRO_SERIAL_VSOCK);
> +
> + qdev_prop_set_chr(dev, "chardev", chr);
> + sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);
> + }
> + }
> +
> + /*
> + * Spawn vCPUs. While the real Nitro Enclaves CPUs are owned by the
> + * underlying hypervisor, we still want to maintain a local view of
> + * them to trigger VM creation when vCPU 0 starts and to give us an
> + * object to interact with.
> + */
> + for (i = 0; i < machine->smp.cpus; i++) {
> + nitro_create_cpu(cpu_type, i);
> + }
> +}
> +
> +static bool nitro_create_memfd_backend(MachineState *ms, const char *path,
> + Error **errp)
> +{
> + MachineClass *mc = MACHINE_GET_CLASS(ms);
> + Object *root = object_get_objects_root();
> + Object *obj;
> + bool r = false;
> +
> + obj = object_new(TYPE_MEMORY_BACKEND_MEMFD);
> +
> + /* Nitro Enclaves require huge page backing */
> + if (!object_property_set_int(obj, "size", ms->ram_size, errp) ||
> + !object_property_set_bool(obj, "hugetlb", true, errp)) {
> + goto out;
> + }
> +
> + object_property_add_child(root, mc->default_ram_id, obj);
> +
> + if (!user_creatable_complete(USER_CREATABLE(obj), errp)) {
> + goto out;
> + }
> + r = object_property_set_link(OBJECT(ms), "memory-backend", obj, errp);
> +
> +out:
> + object_unref(obj);
> + return r;
> +}
> +
> +static void nitro_machine_class_init(ObjectClass *oc, const void *data)
> +{
> + MachineClass *mc = MACHINE_CLASS(oc);
> +
> + mc->desc = "Nitro Enclave";
> + mc->init = nitro_machine_init;
> + mc->create_default_memdev = nitro_create_memfd_backend;
> + mc->default_ram_id = "ram";
> + mc->max_cpus = 4096;
> +}
> +
> +static const TypeInfo nitro_machine_info = {
> + .name = TYPE_NITRO_MACHINE,
> + .parent = TYPE_MACHINE,
> + .instance_size = sizeof(NitroMachineState),
> + .class_init = nitro_machine_class_init,
> + .interfaces = (const InterfaceInfo[]) {
> + /* x86_64 and aarch64 only */
> + { TYPE_TARGET_AARCH64_MACHINE },
> + { }
> + },
> +};
> +
> +static void nitro_machine_register(void)
> +{
> + type_register_static(&nitro_machine_info);
> +}
> +
> +type_init(nitro_machine_register);
> diff --git a/hw/nitro/meson.build b/hw/nitro/meson.build
> index b921da2b97..813f5a9c87 100644
> --- a/hw/nitro/meson.build
> +++ b/hw/nitro/meson.build
> @@ -1,2 +1,3 @@
> system_ss.add(when: 'CONFIG_NITRO_SERIAL_VSOCK', if_true:
> files('serial-vsock.c'))
> system_ss.add(when: 'CONFIG_NITRO_HEARTBEAT', if_true: files('heartbeat.c'))
> +system_ss.add(when: 'CONFIG_NITRO_MACHINE', if_true: files('machine.c'))
> diff --git a/include/hw/nitro/machine.h b/include/hw/nitro/machine.h
> new file mode 100644
> index 0000000000..d78ba7d6dc
> --- /dev/null
> +++ b/include/hw/nitro/machine.h
> @@ -0,0 +1,20 @@
> +/*
> + * Nitro Enclaves (accel) machine
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + */
> +
> +#ifndef HW_NITRO_MACHINE_H
> +#define HW_NITRO_MACHINE_H
> +
> +#include "hw/core/boards.h"
> +#include "qom/object.h"
> +
> +#define TYPE_NITRO_MACHINE MACHINE_TYPE_NAME("nitro")
> +OBJECT_DECLARE_SIMPLE_TYPE(NitroMachineState, NITRO_MACHINE)
> +
> +struct NitroMachineState {
> + MachineState parent;
> +};
> +
> +#endif /* HW_NITRO_MACHINE_H */
> --
> 2.47.1
>
>
>
>
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