Answer

Please enter BIOS setup menu -> Overclocking -> Advanced CPU Configuration -> AMD CBS -> IOMMU=Enabled. And then you will find DMA protection option.

Models

MEG X670E GODLIKE, MEG X670E ACE, PRO X670-P WIFI, X670E GAMING PLUS WIFI, MAG X670E TOMAHAWK WIFI, MPG X670E CARBON WIFI