Note that `dmesg` prints from a fixed-size ring buffer, so if your system has significant other output (e.g. if you create and destroy lots of devices or such), it's very possible the boot-time message about page table isolation will have fallen out of the ring buffer.

If you use journald, it by default saves the kernel's ring buffer to disk, so you can use it to check for that message:

sudo journalctl -b -o cat | grep "page table isolation"