feat(os): add extensible dstack-tee-simulator for no-TEE dev VMs

Add a FUSE-based TEE simulator (default TDX backend) that exposes the
configfs-tsm quote, RTMR, and CCEL interfaces used by the existing guest
path. Packaged only into development images.

Author: kvinwang

CONTRIBUTING.md

@@ -32,6 +32,41 @@ Use the narrowest owning directory. Fixture explanations and component
 READMEs should stay with their fixtures/components; general guides should be
 linked from the root README and live under `docs/`.
 
+## Test a guest without TEE hardware
+
+Development images include the extensible `dstack-tee-simulator`. Its default
+platform backend is TDX. On a VM launched with `no_tee`, that backend exposes
+the Linux interfaces used by the normal guest software:
+
+- configfs-tsm quote generation under `/sys/kernel/config/tsm/report`;
+- RTMR extension files used by `tdx-attest`;
+- a CCEL boot-event fixture.
+
+This keeps `dstack-prepare`, measurement, encrypted-storage setup, the guest
+agent, and attestation APIs on their production code paths. The generated quote
+has an intentionally invalid signature, so a production verifier or KMS must
+reject it.
+
+The service uses the default TDX backend. For direct simulator development, the
+same selection can be made explicitly with `dstack-tee-simulator --platform
+tdx`. New TEE platforms are implemented as separate backends behind the shared
+simulator lifecycle.
+
+Build or install a `dstack-dev-*` image, then deploy without KMS or gateway:
+
+```bash
+dstack deploy ./docker-compose.yml \
+  --name no-tee-dev \
+  --image dstack-dev-VERSION \
+  --no-kms \
+  --no-tee
+```
+
+The simulator package is installed only in development images. This mode
+provides no hardware isolation and must never be used with production
+workloads or secrets. Real quote generation, hardware isolation, and KMS
+authorization still require TDX or another supported TEE.
+
 ## Commit Convention
 
 This project uses [Conventional Commits](https://www.conventionalcommits.org/). Please format your commit messages as:

dstack/Cargo.lock

@@ -33,6 +33,7 @@ members = [
     "guest-agent",
     "guest-agent/rpc",
     "guest-agent-simulator",
+    "tee-simulator",
     "vmm",
     "vmm/rpc",
     "gateway",
@@ -122,6 +123,7 @@ chrono = "0.4.40"
 clap = { version = "4.5.32", features = ["derive", "string"] }
 dashmap = "6.1.0"
 fs-err = "3.1.0"
+fuser = "0.16.0"
 path-absolutize = "3.1.1"
 futures = "0.3.31"
 git-version = "0.3.9"

dstack/Cargo.toml

@@ -0,0 +1,28 @@
+# SPDX-FileCopyrightText: © 2026 Phala Network <dstack@phala.network>
+#
+# SPDX-License-Identifier: Apache-2.0
+
+[package]
+name = "dstack-tee-simulator"
+version.workspace = true
+authors.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[[bin]]
+name = "dstack-tee-simulator"
+path = "src/main.rs"
+
+[dependencies]
+anyhow.workspace = true
+cc-eventlog.workspace = true
+clap.workspace = true
+fuser.workspace = true
+libc.workspace = true
+sd-notify.workspace = true
+sha2.workspace = true
+tracing.workspace = true
+tracing-subscriber.workspace = true
+
+[dev-dependencies]
+dcap-qvl.workspace = true

dstack/tee-simulator/Cargo.toml

@@ -0,0 +1,105 @@
+// SPDX-FileCopyrightText: © 2026 Phala Network <dstack@phala.network>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+use std::path::{Path, PathBuf};
+
+use anyhow::{bail, Context, Result};
+use clap::{Parser, ValueEnum};
+use fuser::{Filesystem, MountOption, Session};
+use tracing::info;
+
+mod tdx;
+
+#[derive(Clone, Copy, Debug, Default, Eq, PartialEq, ValueEnum)]
+enum TeePlatform {
+    #[default]
+    Tdx,
+}
+
+#[derive(Parser)]
+#[command(about = "Development-only simulator for Linux TEE guest ABIs")]
+struct Args {
+    /// TEE platform ABI to simulate.
+    #[arg(long, value_enum, default_value = "tdx")]
+    platform: TeePlatform,
+
+    /// Override the platform backend's default mountpoint.
+    #[arg(long)]
+    mountpoint: Option<PathBuf>,
+}
+
+/// Platform-specific simulator backend.
+///
+/// Adding another TEE platform only requires a backend implementation and a
+/// CLI enum variant; the FUSE lifecycle and safety checks remain shared.
+trait TeeBackend {
+    type Fs: Filesystem;
+
+    const PLATFORM: &'static str;
+    const DEFAULT_MOUNTPOINT: &'static str;
+
+    fn create_filesystem() -> Result<Self::Fs>;
+    fn prepare_mountpoint(mountpoint: &Path) -> Result<()>;
+    fn real_tee_available() -> bool;
+}
+
+fn run_backend<B: TeeBackend>(mountpoint_override: Option<PathBuf>) -> Result<()> {
+    let default_mountpoint = Path::new(B::DEFAULT_MOUNTPOINT);
+    let mountpoint = mountpoint_override.as_deref().unwrap_or(default_mountpoint);
+
+    if mountpoint == default_mountpoint && B::real_tee_available() {
+        bail!(
+            "refusing to start the {} simulator when a real TEE device is present",
+            B::PLATFORM
+        );
+    }
+    B::prepare_mountpoint(mountpoint)?;
+
+    let fs = B::create_filesystem()?;
+    let mut session = Session::new(
+        fs,
+        mountpoint,
+        &[
+            MountOption::FSName(format!("dstack-tee-simulator-{}", B::PLATFORM)),
+            MountOption::DefaultPermissions,
+            MountOption::NoSuid,
+            MountOption::NoDev,
+            MountOption::NoExec,
+        ],
+    )
+    .with_context(|| format!("failed to mount FUSE at {}", mountpoint.display()))?;
+
+    info!(
+        platform = B::PLATFORM,
+        mountpoint = %mountpoint.display(),
+        "development TEE simulator ready"
+    );
+    sd_notify::notify(true, &[sd_notify::NotifyState::Ready])
+        .context("failed to notify systemd")?;
+    session.run().context("fuse session failed")?;
+    Ok(())
+}
+
+fn main() -> Result<()> {
+    tracing_subscriber::fmt()
+        .with_env_filter(tracing_subscriber::EnvFilter::from_default_env())
+        .init();
+    let args = Args::parse();
+
+    match args.platform {
+        TeePlatform::Tdx => run_backend::<tdx::TdxBackend>(args.mountpoint),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn defaults_to_tdx() {
+        let args = Args::try_parse_from(["dstack-tee-simulator"]).unwrap();
+        assert_eq!(args.platform, TeePlatform::Tdx);
+        assert!(args.mountpoint.is_none());
+    }
+}