m/node: panic on unknown NMIs

Configure the kernel to panic in case it receives an unknown NMI.

This can be used to induce a crash in a hanging kernel, allowing
crash diagnostics (pstore currently, maybe kdump in the future) to be
used to diagnose the hang.

This can have false positives on some badly-configured client systems,
but is expected to be fine on servers as other server kernels like
ESXi's vmkernel behave the same.

Change-Id: Ie41e7b816be8492636b6fa596c1c299c0a7a0fc2
Reviewed-on: https://review.monogon.dev/c/monogon/+/2754
Tested-by: Jenkins CI
Reviewed-by: Serge Bazanski <serge@monogon.tech>
diff --git a/metropolis/node/BUILD.bazel b/metropolis/node/BUILD.bazel
index b1173db..eb7e870 100644
--- a/metropolis/node/BUILD.bazel
+++ b/metropolis/node/BUILD.bazel
@@ -118,7 +118,7 @@
 
 efi_unified_kernel_image(
     name = "kernel_efi",
-    cmdline = "console=ttyS0,115200 console=ttyS1,115200 console=tty0 quiet rootfstype=erofs init=/init loadpin.exclude=kexec-image,kexec-initramfs",
+    cmdline = "console=ttyS0,115200 console=ttyS1,115200 console=tty0 quiet rootfstype=erofs init=/init loadpin.exclude=kexec-image,kexec-initramfs kernel.unknown_nmi_panic=1",
     initrd = [":ucode"],
     kernel = "//third_party/linux",
     os_release = ":os-release-info",