{
  "schema_version": 1,
  "diagram_type": "sequence",
  "meta": {
    "title": "ctos \u2014 taken SError opt-in sequence",
    "output": "taken-serror.sequence.html",
    "column_fit": "spread",
    "animation": "trace",
    "quality_profile": "showcase"
  },
  "participants": [
    {
      "id": "smoke",
      "type": "external",
      "label": "qemu-smoke",
      "sublabel": "gate"
    },
    {
      "id": "host",
      "type": "backend",
      "label": "serial-inject",
      "sublabel": "QMP"
    },
    {
      "id": "qemu",
      "type": "cloud",
      "label": "Pinned QEMU",
      "sublabel": "virt/a76"
    },
    {
      "id": "guest",
      "type": "backend",
      "label": "ctos guest",
      "sublabel": "EL0"
    },
    {
      "id": "serial",
      "type": "messagebus",
      "label": "Serial",
      "sublabel": "UART"
    }
  ],
  "segments": [
    {
      "from": 160,
      "to": 280,
      "label": "Arm"
    },
    {
      "from": 300,
      "to": 460,
      "label": "Inject"
    },
    {
      "from": 480,
      "to": 620,
      "label": "Taken"
    }
  ],
  "messages": [
    {
      "id": "start-smoke",
      "from": "smoke",
      "to": "qemu",
      "y": 180,
      "label": "CTOS_QEMU + TAKEN",
      "variant": "emphasis"
    },
    {
      "id": "boot-guest",
      "from": "qemu",
      "to": "guest",
      "y": 215,
      "label": "-kernel ctos"
    },
    {
      "id": "arm-cue",
      "from": "guest",
      "to": "serial",
      "y": 250,
      "label": "el0: serror-arm",
      "variant": "emphasis"
    },
    {
      "id": "host-sees",
      "from": "serial",
      "to": "host",
      "y": 330,
      "label": "cue match",
      "variant": "return"
    },
    {
      "id": "qmp-stop",
      "from": "host",
      "to": "qemu",
      "y": 365,
      "label": "QMP stop",
      "variant": "security"
    },
    {
      "id": "qmp-nmi",
      "from": "host",
      "to": "qemu",
      "y": 400,
      "label": "inject-nmi",
      "variant": "emphasis"
    },
    {
      "id": "qmp-cont",
      "from": "host",
      "to": "qemu",
      "y": 435,
      "label": "QMP cont"
    },
    {
      "id": "deliver",
      "from": "qemu",
      "to": "guest",
      "y": 510,
      "label": "SError @ EL0",
      "variant": "emphasis"
    },
    {
      "id": "taken-cue",
      "from": "guest",
      "to": "serial",
      "y": 545,
      "label": "el0: serror",
      "variant": "emphasis"
    },
    {
      "id": "expect-ok",
      "from": "serial",
      "to": "smoke",
      "y": 580,
      "label": "EXPECT ok",
      "variant": "return"
    }
  ],
  "activations": [
    {
      "participant": "qemu",
      "from": 175,
      "to": 520,
      "type": "cloud"
    },
    {
      "participant": "guest",
      "from": 210,
      "to": 555,
      "type": "backend"
    },
    {
      "participant": "host",
      "from": 325,
      "to": 445,
      "type": "backend"
    },
    {
      "participant": "serial",
      "from": 245,
      "to": 590,
      "type": "messagebus"
    }
  ],
  "cards": [
    {
      "dot": "emerald",
      "title": "Taken path (opt-in)",
      "items": [
        "Pinned virt implements TYPE_NMI \u2192 ARM_CPU_SERROR",
        "stop/inject/cont avoids racing past the A-clear window",
        "Serial bare el0: serror satisfies CTOS_REQUIRE_TAKEN_SERROR=1",
        "Arm A-clear window (qemu-smoke, ctos guest, Serial): Guest arms standing EL0 with PSTATE.A clear and prints el0: serror-arm.",
        "QMP stop / inject / cont (serial-inject, Pinned QEMU, ctos guest): Host pauses TCG, inject-nmi raises ARM_CPU_SERROR on the pin, then continues."
      ]
    },
    {
      "dot": "orange",
      "title": "Stock contrast",
      "items": [
        "Without the pin, inject-nmi errors: machine does not provide NMIs",
        "Default smoke still requires el0: serror-park",
        "Diagram is a doc aid \u2014 not production Live status",
        "EXPECT gate (ctos guest, Serial, qemu-smoke): Opt-in smoke requires bare el0: serror; stock path would park instead."
      ]
    },
    {
      "dot": "rose",
      "title": "Honesty",
      "items": [
        "Not FEAT_NMI; not FIQ/BRK as SError",
        "Not umbrella EL0 isolated",
        "ADR-083 tip ~6ec1f4e; CloudAgent HELD for the amd64 workstation"
      ]
    }
  ]
}