Firecracker v1.2.0

Added

• Added a new CPU template called T2S. This exposes the same CPUID as T2 to
  the Guest and also overwrites the ARCH_CAPABILITIES MSR to expose a reduced
  set of capabilities. With regards to hardware vulnerabilities and mitigations,
  the Guest vCPU will apear to look like a Skylake CPU, making it safe to
  snapshot uVMs running on a newer host CPU (Cascade Lake) and restore on a host
  that has a Skylake CPU.
• Added a new CLI option --metrics-path PATH. It accepts a file parameter
  where metrics will be sent to.
• Added baselines for m6i.metal and m6a.metal for all long running performance
  tests.
• Releases now include debuginfo files.

Changed

• Changed the jailer option --exec-file to fail if the filename does not
  contain the string firecracker to prevent from running non-firecracker
  binaries.
• Upgraded Rust toolchain from 1.52.1 to 1.64.0.
• Switched to specifying our dependencies using caret requirements instead
  of comparison requirements.
• Updated all dependencies to their respective newest versions.

Fixed

• Made the T2 template more robust by explicitly disabling additional
  CPUID flags that should be off but were missed initially or that were
  not available in the spec when the template was created.
• Now MAC address is correctly displayed when queried with GET /vm/config
  if left unspecified in both pre and post snapshot states.
• Fixed a self-DoS scenario in the virtio-queue code by reporting and
  terminating execution when the number of available descriptors reported
  by the driver is higher than the queue size.
• Fixed the bad handling of kernel cmdline parameters when init arguments were
  provided in the boot_args field of the JSON body of the PUT /boot-source
  request.
• Fixed a bug on ARM64 hosts where the upper 64bits of the V0-V31 FL/SIMD
  registers were not saved correctly when taking a snapshot, potentially
  leading to data loss. This change invalidates all ARM64 snapshots taken
  with versions of Firecracker <= 1.1.3.
• Improved stability and security when saving CPU MSRs in snapshots.