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3793ffe888
Removing the option --tdx to specify that we want to run a TD VM. Rely on --platform option by adding the "tdx" boolean parameter. This is the new way for enabling TDX with Cloud Hypervisor. Along with this change, the way to retrieve the firmware path has been updated to rely on the recently introduced PayloadConfig structure. Fixes #4556 Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
124 lines
4.1 KiB
Markdown
124 lines
4.1 KiB
Markdown
# Intel TDX
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Intel® Trust Domain Extensions (Intel® TDX) is an Intel technology designed to
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isolate virtual machines from the VMM, hypervisor and any other software on the
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host platform.
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For more information about TDX technical aspects, design and specification
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please refer to the
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[TDX Homepage](https://www.intel.com/content/www/us/en/developer/articles/technical/intel-trust-domain-extensions.html).
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The required Linux changes for the host side can be found in the
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[KVM TDX tree](https://github.com/intel/tdx/tree/kvm) while the changes for
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the guest side can be found in the [Guest TDX tree](https://github.com/intel/tdx/tree/guest).
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The TDVF firmware can be found in the
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[EDK2 staging project](https://github.com/tianocore/edk2-staging/tree/TDVF).
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The TDShim firmware can be found in the
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[Confidential Containers project](https://github.com/confidential-containers/td-shim).
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## Cloud Hypervisor support
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First, you must be running on a machine with TDX enabled in hardware, and
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with the host OS compiled from the [KVM TDX tree](https://github.com/intel/tdx/tree/kvm).
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Cloud Hypervisor can run TDX VM (Trust Domain) by loading a TD firmware,
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which will then load the guest kernel from the image. The image must be custom
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as it must include a kernel built from the [Guest TDX tree](https://github.com/intel/tdx/tree/guest).
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### TDVF
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The firmware can be built as follows:
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```bash
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git clone https://github.com/tianocore/edk2-staging.git
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cd edk2-staging
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git checkout origin/TDVF
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git submodule update --init --recursive
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make -C BaseTools
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source ./edksetup.sh
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build -p OvmfPkg/OvmfCh.dsc -a X64 -t GCC5 -b RELEASE
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```
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If debug logs are needed, here is the alternative command:
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```bash
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build -p OvmfPkg/OvmfCh.dsc -a X64 -t GCC5 -D DEBUG_ON_SERIAL_PORT=TRUE
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```
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On the Cloud Hypervisor side, all you need is to build the project with the
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`tdx` feature enabled:
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```bash
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cargo build --features tdx
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```
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And run a TDX VM by providing the firmware previously built, along with the
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guest image containing the TDX enlightened kernel. The latest image
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`td-guest-rhel8.5.raw` contains `console=hvc0` on the kernel boot parameters,
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meaning it will be printing guest kernel logs to the `virtio-console` device.
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```bash
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./cloud-hypervisor \
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--platform tdx=on
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--firmware edk2-staging/Build/OvmfCh/RELEASE_GCC5/FV/OVMF.fd \
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--cpus boot=1 \
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--memory size=1G \
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--disk path=tdx_guest_img
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```
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And here is the alternative command when looking for debug logs from the
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firmware:
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```bash
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./cloud-hypervisor \
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--platform tdx=on
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--firmware edk2-staging/Build/OvmfCh/DEBUG_GCC5/FV/OVMF.fd \
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--cpus boot=1 \
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--memory size=1G \
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--disk path=tdx_guest_img \
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--serial file=/tmp/ch_serial \
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--console tty
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```
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### TDShim
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This is a lightweight version of the TDVF, written in Rust and designed for
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direct kernel boot, which is useful for containers use cases.
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You can find the instructions for building the firmware directly from the
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project [documentation](https://github.com/confidential-containers/td-shim/tree/staging#how-to-build).
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And run a TDX VM by providing the firmware previously built, along with a guest
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kernel built from the [Guest TDX tree](https://github.com/intel/tdx/tree/guest).
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The appropriate kernel boot options must be provided through the `--cmdline`
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option as well.
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```bash
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./cloud-hypervisor \
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--platform tdx=on
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--firmware tdshim \
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--kernel bzImage \
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--cmdline "root=/dev/vda3 console=hvc0 rw"
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--cpus boot=1 \
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--memory size=1G \
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--disk path=tdx_guest_img
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```
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### Guest kernel limitations
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#### Serial ports disabled
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The latest guest kernel that can be found in the latest image
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`td-guest-rhel8.5.raw` disabled the support for serial ports. This means adding
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`console=ttyS0` will have no effect and will not print any log from the guest.
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#### PCI hotplug through ACPI
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Unless you run the guest kernel with the parameter `tdx_disable_filter`, ACPI
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devices responsible for handling PCI hotplug (PCI hotplug controller, PCI
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Express Bus and Generic Event Device) will not be allowed, therefore the
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corresponding drivers will not be loaded and the PCI hotplug feature will not
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be supported.
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