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Subject: Re: [RFC PATCH v2 68/69] KVM: TDX: add document on TDX MODULE
To:     isaku.yamahata@intel.com, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H . Peter Anvin" <hpa@zytor.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>, erdemaktas@google.com,
        Connor Kuehl <ckuehl@redhat.com>,
        Sean Christopherson <seanjc@google.com>, x86@kernel.org,
        linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc:     isaku.yamahata@gmail.com
References: <cover.1625186503.git.isaku.yamahata@intel.com>
 <b5d0446fedfe5d47a8aa5e623f39cb04d62837ce.1625186503.git.isaku.yamahata@intel.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <636f315e-f1d0-0e2c-849c-b7f393da2bc9@redhat.com>
Date:   Tue, 6 Jul 2021 16:23:49 +0200
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On 03/07/21 00:05, isaku.yamahata@intel.com wrote:
> From: Isaku Yamahata <isaku.yamahata@intel.com>
> 
> Add a document on how to integrate TDX MODULE into initrd so that
> TDX MODULE can be updated on kernel startup.
> 
> Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> ---
>   Documentation/virt/kvm/tdx-module.rst | 48 +++++++++++++++++++++++++++
>   1 file changed, 48 insertions(+)
>   create mode 100644 Documentation/virt/kvm/tdx-module.rst
> 
> diff --git a/Documentation/virt/kvm/tdx-module.rst b/Documentation/virt/kvm/tdx-module.rst
> new file mode 100644
> index 000000000000..8beea8302f94
> --- /dev/null
> +++ b/Documentation/virt/kvm/tdx-module.rst
> @@ -0,0 +1,48 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +==========
> +TDX MODULE
> +==========
> +
> +Integrating TDX MODULE into initrd
> +==================================
> +If TDX is enabled in KVM(CONFIG_KVM_INTEL_TDX=y), kernel is able to load
> +tdx seam module from initrd.
> +The related modules (seamldr.ac, libtdx.so and libtdx.so.sigstruct) need to be
> +stored in initrd.
> +
> +tdx-seam is a sample hook script for initramfs-tools.
> +TDXSEAM_SRCDIR are the directory in the host file system to store files related
> +to TDX MODULE.
> +
> +Since it heavily depends on distro how to prepare initrd, here's a example how
> +to prepare an initrd.
> +(Actually this is taken from Documentation/x86/microcode.rst)
> +::
> +  #!/bin/bash
> +
> +  if [ -z "$1" ]; then
> +      echo "You need to supply an initrd file"
> +      exit 1
> +  fi
> +
> +  INITRD="$1"
> +
> +  DSTDIR=lib/firmware/intel-seam
> +  TMPDIR=/tmp/initrd
> +  LIBTDX="/lib/firmware/intel-seam/seamldr.acm /lib/firmware/intel-seam/libtdx.so /lib/firmware/intel-seam/libtdx.so.sigstruct"
> +
> +  rm -rf $TMPDIR
> +
> +  mkdir $TMPDIR
> +  cd $TMPDIR
> +  mkdir -p $DSTDIR
> +
> +  cp ${LIBTDX} ${DSTDIR}
> +
> +  find . | cpio -o -H newc > ../tdx-seam.cpio
> +  cd ..
> +  mv $INITRD $INITRD.orig
> +  cat tdx-seam.cpio $INITRD.orig > $INITRD
> +
> +  rm -rf $TMPDIR
> 

I think this belongs in a different series that adds SEAM loading?

Paolo