| 1 | /* |
| 2 | * Nitro Enclave Heartbeat device |
| 3 | * |
| 4 | * Copyright © 2026 Amazon.com, Inc. or its affiliates. All Rights Reserved. |
| 5 | * |
| 6 | * Authors: |
| 7 | * Alexander Graf <graf@amazon.com> |
| 8 | * |
| 9 | * The Nitro Enclave init process sends a heartbeat byte (0xB7) to |
| 10 | * CID 3 (parent) port 9000 on boot to signal it reached initramfs. |
| 11 | * The parent must accept the connection, read the byte, and echo it |
| 12 | * back. If the enclave init cannot reach the listener, it exits. |
| 13 | * |
| 14 | * SPDX-License-Identifier: GPL-2.0-or-later |
| 15 | */ |
| 16 | |
| 17 | #include "qemu/osdep.h" |
| 18 | #include "qapi/error.h" |
| 19 | #include "chardev/char.h" |
| 20 | #include "chardev/char-fe.h" |
| 21 | #include "hw/nitro/heartbeat.h" |
| 22 | #include "trace.h" |
| 23 | |
| 24 | #define HEARTBEAT_PORT 9000 |
| 25 | #define VMADDR_CID_ANY_STR "4294967295" |
| 26 | |
| 27 | static int nitro_heartbeat_can_read(void *opaque) |
| 28 | { |
| 29 | NitroHeartbeatState *s = opaque; |
| 30 | |
| 31 | /* One-shot protocol: stop reading after the first heartbeat */ |
| 32 | return s->done ? 0 : 1; |
| 33 | } |
| 34 | |
| 35 | static void nitro_heartbeat_read(void *opaque, const uint8_t *buf, int size) |
| 36 | { |
| 37 | NitroHeartbeatState *s = opaque; |
| 38 | |
| 39 | if (s->done || size < 1) { |
| 40 | return; |
| 41 | } |
| 42 | |
| 43 | /* Echo the heartbeat byte back and disconnect */ |
| 44 | qemu_chr_fe_write_all(&s->vsock, buf, 1); |
| 45 | s->done = true; |
| 46 | qemu_chr_fe_deinit(&s->vsock, true); |
| 47 | |
| 48 | trace_nitro_heartbeat_done(); |
| 49 | } |
| 50 | |
| 51 | static void nitro_heartbeat_event(void *opaque, QEMUChrEvent event) |
| 52 | { |
| 53 | trace_nitro_heartbeat_event(event); |
| 54 | } |
| 55 | |
| 56 | static void nitro_heartbeat_realize(DeviceState *dev, Error **errp) |
| 57 | { |
| 58 | NitroHeartbeatState *s = NITRO_HEARTBEAT(dev); |
| 59 | g_autofree char *chardev_id = NULL; |
| 60 | Chardev *chr; |
| 61 | ChardevBackend *backend; |
| 62 | ChardevSocket *sock; |
| 63 | |
| 64 | chardev_id = g_strdup_printf("nitro-heartbeat"); |
| 65 | |
| 66 | backend = g_new0(ChardevBackend, 1); |
| 67 | backend->type = CHARDEV_BACKEND_KIND_SOCKET; |
| 68 | sock = backend->u.socket.data = g_new0(ChardevSocket, 1); |
| 69 | sock->addr = g_new0(SocketAddressLegacy, 1); |
| 70 | sock->addr->type = SOCKET_ADDRESS_TYPE_VSOCK; |
| 71 | sock->addr->u.vsock.data = g_new0(VsockSocketAddress, 1); |
| 72 | sock->addr->u.vsock.data->cid = g_strdup(VMADDR_CID_ANY_STR); |
| 73 | sock->addr->u.vsock.data->port = g_strdup_printf("%u", HEARTBEAT_PORT); |
| 74 | sock->server = true; |
| 75 | sock->has_server = true; |
| 76 | sock->wait = false; |
| 77 | sock->has_wait = true; |
| 78 | |
| 79 | chr = qemu_chardev_new(chardev_id, TYPE_CHARDEV_SOCKET, |
| 80 | backend, NULL, errp); |
| 81 | if (!chr) { |
| 82 | return; |
| 83 | } |
| 84 | |
| 85 | if (!qemu_chr_fe_init(&s->vsock, chr, errp)) { |
| 86 | return; |
| 87 | } |
| 88 | |
| 89 | qemu_chr_fe_set_handlers(&s->vsock, |
| 90 | nitro_heartbeat_can_read, |
| 91 | nitro_heartbeat_read, |
| 92 | nitro_heartbeat_event, |
| 93 | NULL, s, NULL, true); |
| 94 | } |
| 95 | |
| 96 | static void nitro_heartbeat_class_init(ObjectClass *oc, const void *data) |
| 97 | { |
| 98 | DeviceClass *dc = DEVICE_CLASS(oc); |
| 99 | |
| 100 | dc->realize = nitro_heartbeat_realize; |
| 101 | } |
| 102 | |
| 103 | static const TypeInfo nitro_heartbeat_info = { |
| 104 | .name = TYPE_NITRO_HEARTBEAT, |
| 105 | .parent = TYPE_NITRO_VSOCK_DEVICE, |
| 106 | .instance_size = sizeof(NitroHeartbeatState), |
| 107 | .class_init = nitro_heartbeat_class_init, |
| 108 | }; |
| 109 | |
| 110 | static void nitro_heartbeat_register(void) |
| 111 | { |
| 112 | type_register_static(&nitro_heartbeat_info); |
| 113 | } |
| 114 | |
| 115 | type_init(nitro_heartbeat_register); |