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mkimage: emit digest.sev.txt (AMD SEV-SNP os_image_hash) #71

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mkimage: emit digest.sev.txt (AMD SEV-SNP os_image_hash) #71

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ba97573
mkimage: emit digest.sev.txt (AMD SEV-SNP os_image_hash)
kvinwang Jun 17, 2026
dcf4070
mkimage: compute digest.sev.txt via dstack-mr, build it if needed
kvinwang Jun 18, 2026
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28 changes: 28 additions & 0 deletions mkimage.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -300,6 +300,31 @@ sha256sum ovmf.fd bzImage initramfs.cpio.gz metadata.json > sha256sum.txt
sha256sum sha256sum.txt | awk '{print $1}' > digest.txt
popd

# digest.sev.txt: the AMD SEV-SNP os_image_hash. Unlike the TDX digest.txt
# (a content hash that includes the TDX firmware), this is computed by the
# `dstack-mr` tool from the SEV firmware (ovmf-sev.fd) + kernel/initrd/cmdline/
# rootfs and matches the os_image_hash the KMS verifier derives from a launch
# measurement. The VMM reads this file at deploy time instead of recomputing it,
# so it is required (not best-effort): if `dstack-mr` is not prebuilt, build it.
HAVE_DIGEST_SEV=0
if [ "$HAVE_OVMF_SEV" = "1" ]; then
DSTACK_SRC="${DSTACK_SRC:-$SCRIPT_DIR/dstack}"
if [ -z "${DSTACK_MR_BIN:-}" ]; then
for c in "$SCRIPT_DIR/dstack-mr" "$SCRIPT_DIR/rust-target/release/dstack-mr" \
"$DSTACK_SRC/target/release/dstack-mr"; do
[ -x "$c" ] && DSTACK_MR_BIN="$c" && break
done
fi
if [ -z "${DSTACK_MR_BIN:-}" ]; then
echo "Building dstack-mr to compute digest.sev.txt"
( cd "$DSTACK_SRC" && cargo build --release -p dstack-mr )
DSTACK_MR_BIN="$DSTACK_SRC/target/release/dstack-mr"
fi
echo "Generating digest.sev.txt via ${DSTACK_MR_BIN}"
"${DSTACK_MR_BIN}" sev-os-image-hash "${OUTPUT_DIR}" > "${OUTPUT_DIR}/digest.sev.txt"
HAVE_DIGEST_SEV=1
fi

# Create UKI artifacts (disk.raw and auth_hash.txt) in OUTPUT_DIR
UKI_CREATED=0
if [ "$ENABLE_UKI_IMAGE" = "1" ]; then
Expand Down Expand Up @@ -331,6 +356,9 @@ if [ x$DSTACK_TAR_RELEASE = x1 ]; then
if [ "$HAVE_OVMF_SEV" = "1" ]; then
BARE_METAL_FILES="$BARE_METAL_FILES ovmf-sev.fd"
fi
if [ "$HAVE_DIGEST_SEV" = "1" ]; then
BARE_METAL_FILES="$BARE_METAL_FILES digest.sev.txt"
fi
(cd "$PARENT_DIR" && tar -czvf ${IMAGE_TAR} $(for f in $BARE_METAL_FILES; do echo "$TAR_DIR_NAME/$f"; done))
echo

Expand Down