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Nitro Enclaves are a confidential compute technology which allows a parent instance to carve out resources from itself and spawn a confidential sibling VM next to itself. Similar to other confidential compute solutions, this sibling is controlled by an underlying vmm, but still has a higher level vmm (QEMU) to implement some of its I/O functionality and lifecycle. Add an accelerator to drive this interface. In combination with follow-on patches to enhance the Nitro Enclaves machine model, this will allow users to run a Nitro Enclave using QEMU. Signed-off-by: Alexander Graf <graf@amazon.com> Link: https://lore.kernel.org/r/20260225220807.33092-5-graf@amazon.com Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>master
Alexander Graf
1 month ago
committed by
Paolo Bonzini
Paolo Bonzini
15 changed files with 364 additions and 4 deletions
@ -0,0 +1,3 @@ |
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nitro_ss = ss.source_set() |
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nitro_ss.add(files('nitro-accel.c')) |
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system_ss.add_all(when: 'CONFIG_NITRO', if_true: nitro_ss) |
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@ -0,0 +1,284 @@ |
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/*
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* Nitro Enclaves accelerator |
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* |
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* Copyright © 2026 Amazon.com, Inc. or its affiliates. All Rights Reserved. |
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* |
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* Authors: |
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* Alexander Graf <graf@amazon.com> |
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* |
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* Nitro Enclaves are a confidential compute technology which |
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* allows a parent instance to carve out resources from itself |
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* and spawn a confidential sibling VM next to itself. Similar |
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* to other confidential compute solutions, this sibling is |
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* controlled by an underlying vmm, but still has a higher level |
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* vmm (QEMU) to implement some of its I/O functionality and |
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* lifecycle. |
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* |
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* This accelerator drives /dev/nitro_enclaves to spawn a Nitro |
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* Enclave. It works in tandem with the nitro_enclaves machine |
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* which ensures the correct backend devices are available and |
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* that the initial seed (an EIF file) is loaded at the correct |
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* offset in memory. |
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* |
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* The accel starts the enclave when the machine starts, after |
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* all device setup is finished. |
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* |
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* SPDX-License-Identifier: GPL-2.0-or-later |
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*/ |
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|
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#include "qemu/osdep.h" |
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#include "qemu/error-report.h" |
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#include "qapi/error.h" |
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#include "qapi/visitor.h" |
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#include "qemu/module.h" |
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#include "qemu/rcu.h" |
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#include "qemu/accel.h" |
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#include "qemu/guest-random.h" |
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#include "qemu/main-loop.h" |
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#include "accel/accel-ops.h" |
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#include "accel/accel-cpu-ops.h" |
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#include "accel/dummy-cpus.h" |
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#include "system/cpus.h" |
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#include "hw/core/cpu.h" |
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#include "hw/core/boards.h" |
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#include "hw/nitro/nitro-vsock-bus.h" |
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#include "system/ramblock.h" |
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#include "system/nitro-accel.h" |
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#include "trace.h" |
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|
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#include <sys/ioctl.h> |
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#include "standard-headers/linux/nitro_enclaves.h" |
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bool nitro_allowed; |
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typedef struct NitroAccelState { |
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AccelState parent_obj; |
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int ne_fd; |
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int enclave_fd; |
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uint64_t slot_uid; |
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uint64_t enclave_cid; |
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bool debug_mode; |
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} NitroAccelState; |
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static int nitro_init_machine(AccelState *as, MachineState *ms) |
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{ |
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NitroAccelState *s = NITRO_ACCEL(as); |
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uint64_t slot_uid = 0; |
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int ret; |
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s->ne_fd = open("/dev/nitro_enclaves", O_RDWR | O_CLOEXEC); |
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if (s->ne_fd < 0) { |
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error_report("nitro: failed to open /dev/nitro_enclaves: %s", |
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strerror(errno)); |
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return -errno; |
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} |
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ret = ioctl(s->ne_fd, NE_CREATE_VM, &slot_uid); |
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if (ret < 0) { |
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error_report("nitro: NE_CREATE_VM failed: %s", strerror(errno)); |
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close(s->ne_fd); |
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return -errno; |
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} |
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s->enclave_fd = ret; |
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s->slot_uid = slot_uid; |
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return 0; |
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} |
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static int nitro_donate_ram_block(RAMBlock *rb, void *opaque) |
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{ |
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NitroAccelState *s = opaque; |
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struct ne_user_memory_region region = { |
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.flags = 0, |
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.memory_size = rb->used_length, |
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.userspace_addr = (uint64_t)(uintptr_t)rb->host, |
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}; |
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|
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if (!rb->used_length) { |
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return 0; |
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} |
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if (ioctl(s->enclave_fd, NE_SET_USER_MEMORY_REGION, ®ion) < 0) { |
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error_report("nitro: NE_SET_USER_MEMORY_REGION failed for %s " |
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"(%" PRIu64 " bytes): %s", rb->idstr, rb->used_length, |
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strerror(errno)); |
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return -errno; |
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} |
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return 0; |
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} |
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|
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/*
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* Start the Enclave. At this point memory is set up and the EIF is loaded. |
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* This function donates memory, adds vCPUs, and starts the enclave. |
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*/ |
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static void nitro_setup_post(AccelState *as) |
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{ |
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MachineState *ms = MACHINE(qdev_get_machine()); |
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NitroAccelState *s = NITRO_ACCEL(as); |
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int nr_cpus = ms->smp.cpus; |
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int i, ret; |
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struct ne_enclave_start_info start_info = { |
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.flags = s->debug_mode ? NE_ENCLAVE_DEBUG_MODE : 0, |
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.enclave_cid = s->enclave_cid, |
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}; |
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ret = qemu_ram_foreach_block(nitro_donate_ram_block, s); |
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if (ret < 0) { |
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error_report("nitro: failed to donate memory"); |
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exit(1); |
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} |
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for (i = 0; i < nr_cpus; i++) { |
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uint32_t cpu_id = 0; |
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if (ioctl(s->enclave_fd, NE_ADD_VCPU, &cpu_id) < 0) { |
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error_report("nitro: NE_ADD_VCPU failed: %s", strerror(errno)); |
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exit(1); |
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} |
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} |
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ret = ioctl(s->enclave_fd, NE_START_ENCLAVE, &start_info); |
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if (ret < 0) { |
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switch (errno) { |
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case NE_ERR_NO_MEM_REGIONS_ADDED: |
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error_report("nitro: no memory regions added"); |
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break; |
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case NE_ERR_NO_VCPUS_ADDED: |
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error_report("nitro: no vCPUs added"); |
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break; |
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case NE_ERR_ENCLAVE_MEM_MIN_SIZE: |
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error_report("nitro: memory is below the minimum " |
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"required size. Try increasing -m"); |
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break; |
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case NE_ERR_FULL_CORES_NOT_USED: |
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error_report("nitro: requires full CPU cores. " |
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"Try increasing -smp to a multiple of threads " |
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"per core on this host (e.g. -smp 2)"); |
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break; |
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case NE_ERR_NOT_IN_INIT_STATE: |
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error_report("nitro: not in init state"); |
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break; |
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case NE_ERR_INVALID_FLAG_VALUE: |
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error_report("nitro: invalid flag value for NE_START_ENCLAVE"); |
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break; |
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case NE_ERR_INVALID_ENCLAVE_CID: |
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error_report("nitro: invalid enclave CID"); |
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break; |
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default: |
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error_report("nitro: NE_START_ENCLAVE failed: %s (errno %d)", |
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strerror(errno), errno); |
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break; |
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} |
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exit(1); |
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} |
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s->enclave_cid = start_info.enclave_cid; |
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trace_nitro_enclave_started(s->enclave_cid); |
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/*
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* Notify all Nitro vsock bus devices that the enclave has started |
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* and provide them with the CID for vsock connections. |
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*/ |
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{ |
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NitroVsockBridge *bridge = nitro_vsock_bridge_find(); |
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Error *err = NULL; |
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if (bridge) { |
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nitro_vsock_bridge_start_enclave(bridge, |
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(uint32_t)s->enclave_cid, &err); |
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if (err) { |
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error_report_err(err); |
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exit(1); |
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} |
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} |
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} |
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} |
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/* QOM properties */ |
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static bool nitro_get_debug_mode(Object *obj, Error **errp) |
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{ |
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return NITRO_ACCEL(obj)->debug_mode; |
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} |
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static void nitro_set_debug_mode(Object *obj, bool value, Error **errp) |
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{ |
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NITRO_ACCEL(obj)->debug_mode = value; |
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} |
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static void nitro_get_enclave_cid(Object *obj, Visitor *v, |
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const char *name, void *opaque, |
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Error **errp) |
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{ |
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uint64_t val = NITRO_ACCEL(obj)->enclave_cid; |
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visit_type_uint64(v, name, &val, errp); |
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} |
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static void nitro_set_enclave_cid(Object *obj, Visitor *v, |
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const char *name, void *opaque, |
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Error **errp) |
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{ |
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uint64_t val; |
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if (visit_type_uint64(v, name, &val, errp)) { |
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NITRO_ACCEL(obj)->enclave_cid = val; |
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} |
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} |
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static void nitro_accel_class_init(ObjectClass *oc, const void *data) |
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{ |
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AccelClass *ac = ACCEL_CLASS(oc); |
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ac->name = "Nitro"; |
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ac->init_machine = nitro_init_machine; |
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ac->setup_post = nitro_setup_post; |
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ac->allowed = &nitro_allowed; |
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object_class_property_add_bool(oc, "debug-mode", |
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nitro_get_debug_mode, |
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nitro_set_debug_mode); |
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object_class_property_set_description(oc, "debug-mode", |
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"Start enclave in debug mode (enables console output)"); |
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object_class_property_add(oc, "enclave-cid", "uint64", |
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nitro_get_enclave_cid, |
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nitro_set_enclave_cid, |
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NULL, NULL); |
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object_class_property_set_description(oc, "enclave-cid", |
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"Enclave CID (0 = auto-assigned by Nitro)"); |
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} |
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static const TypeInfo nitro_accel_type = { |
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.name = TYPE_NITRO_ACCEL, |
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.parent = TYPE_ACCEL, |
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.instance_size = sizeof(NitroAccelState), |
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.class_init = nitro_accel_class_init, |
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}; |
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module_obj(TYPE_NITRO_ACCEL); |
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static bool nitro_cpus_are_resettable(void) |
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{ |
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return false; |
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} |
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static void nitro_accel_ops_class_init(ObjectClass *oc, const void *data) |
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{ |
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AccelOpsClass *ops = ACCEL_OPS_CLASS(oc); |
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ops->create_vcpu_thread = dummy_start_vcpu_thread; |
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ops->handle_interrupt = generic_handle_interrupt; |
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ops->cpus_are_resettable = nitro_cpus_are_resettable; |
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} |
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static const TypeInfo nitro_accel_ops_type = { |
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.name = ACCEL_OPS_NAME("nitro"), |
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.parent = TYPE_ACCEL_OPS, |
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.class_init = nitro_accel_ops_class_init, |
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.abstract = true, |
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}; |
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module_obj(ACCEL_OPS_NAME("nitro")); |
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|
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static void nitro_type_init(void) |
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{ |
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type_register_static(&nitro_accel_type); |
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type_register_static(&nitro_accel_ops_type); |
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} |
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type_init(nitro_type_init); |
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@ -0,0 +1,6 @@ |
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# SPDX-License-Identifier: GPL-2.0-or-later |
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# |
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# See docs/devel/tracing.rst for syntax documentation. |
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# nitro-accel.c |
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nitro_enclave_started(uint64_t cid) "nitro: enclave started, CID=%"PRIu64 |
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@ -0,0 +1,2 @@ |
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/* SPDX-License-Identifier: GPL-2.0-or-later */ |
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#include "trace/trace-accel_nitro.h" |
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@ -0,0 +1,11 @@ |
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/*
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* Nitro accel stubs for QEMU |
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* |
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* Copyright © 2026 Amazon.com, Inc. or its affiliates. All Rights Reserved. |
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* |
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* SPDX-License-Identifier: GPL-2.0-or-later |
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*/ |
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|
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#include "qemu/osdep.h" |
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bool nitro_allowed; |
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@ -0,0 +1,25 @@ |
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/*
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* Nitro Enclaves accelerator - public interface |
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* |
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* SPDX-License-Identifier: GPL-2.0-or-later |
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*/ |
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#ifndef SYSTEM_NITRO_ACCEL_H |
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#define SYSTEM_NITRO_ACCEL_H |
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#include "qemu/accel.h" |
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extern bool nitro_allowed; |
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static inline bool nitro_enabled(void) |
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{ |
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return nitro_allowed; |
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} |
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#define TYPE_NITRO_ACCEL ACCEL_CLASS_NAME("nitro") |
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typedef struct NitroAccelState NitroAccelState; |
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DECLARE_INSTANCE_CHECKER(NitroAccelState, NITRO_ACCEL, |
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TYPE_NITRO_ACCEL) |
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#endif /* SYSTEM_NITRO_ACCEL_H */ |
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