machine/nitro-enclave: New machine type for AWS Nitro Enclaves

AWS nitro enclaves[1] is an Amazon EC2[2] feature that allows creating
isolated execution environments, called enclaves, from Amazon EC2
instances which are used for processing highly sensitive data. Enclaves
have no persistent storage and no external networking. The enclave VMs
are based on the Firecracker microvm with a vhost-vsock device for
communication with the parent EC2 instance that spawned it and a Nitro
Secure Module (NSM) device for cryptographic attestation. The parent
instance VM always has CID 3 while the enclave VM gets a dynamic CID.

An EIF (Enclave Image Format)[3] file is used to boot an AWS nitro enclave
virtual machine. This commit adds support for AWS nitro enclave emulation
using a new machine type option '-M nitro-enclave'. This new machine type
is based on the 'microvm' machine type, similar to how real nitro enclave
VMs are based on Firecracker microvm. For nitro-enclave to boot from an
EIF file, the kernel and ramdisk(s) are extracted into a temporary kernel
and a temporary initrd file which are then hooked into the regular x86
boot mechanism along with the extracted cmdline. The EIF file path should
be provided using the '-kernel' QEMU option.

In QEMU, the vsock emulation for nitro enclave is added using vhost-user-
vsock as opposed to vhost-vsock. vhost-vsock doesn't support sibling VM
communication which is needed for nitro enclaves. So for the vsock
communication to CID 3 to work, another process that does the vsock
emulation in  userspace must be run, for example, vhost-device-vsock[4]
from rust-vmm, with necessary vsock communication support in another
guest VM with CID 3. Using vhost-user-vsock also enables the possibility
to implement some proxying support in the vhost-user-vsock daemon that
will forward all the packets to the host machine instead of CID 3 so
that users of nitro-enclave can run the necessary applications in their
host machine instead of running another whole VM with CID 3. The following
mandatory nitro-enclave machine option has been added related to the
vhost-user-vsock device.
  - 'vsock': The chardev id from the '-chardev' option for the
vhost-user-vsock device.

AWS Nitro Enclaves have built-in Nitro Secure Module (NSM) device which
has been added using the virtio-nsm device added in a previous commit.
In Nitro Enclaves, all the PCRs start in a known zero state and the first
16 PCRs are locked from boot and reserved. The PCR0, PCR1, PCR2 and PCR8
contain the SHA384 hashes related to the EIF file used to boot the VM
for validation. The following optional nitro-enclave machine options
have been added related to the NSM device.
  - 'id': Enclave identifier, reflected in the module-id of the NSM
device. If not provided, a default id will be set.
  - 'parent-role': Parent instance IAM role ARN, reflected in PCR3
of the NSM device.
  - 'parent-id': Parent instance identifier, reflected in PCR4 of the
NSM device.

[1] https://docs.aws.amazon.com/enclaves/latest/user/nitro-enclave.html
[2] https://aws.amazon.com/ec2/
[3] https://github.com/aws/aws-nitro-enclaves-image-format
[4] https://github.com/rust-vmm/vhost-device/tree/main/vhost-device-vsock

Signed-off-by: Dorjoy Chowdhury <dorjoychy111@gmail.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
Link: https://lore.kernel.org/r/20241008211727.49088-6-dorjoychy111@gmail.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/configs/devices/i386-softmmu/default.mak b/configs/devices/i386-softmmu/default.mak
index 448e3e3b1b..4faf2f0315 100644
--- a/configs/devices/i386-softmmu/default.mak
+++ b/configs/devices/i386-softmmu/default.mak
@@ -29,3 +29,4 @@
 # CONFIG_I440FX=n
 # CONFIG_Q35=n
 # CONFIG_MICROVM=n
+# CONFIG_NITRO_ENCLAVE=n