On Tue, 28 Jan 2020, Kees Cook wrote: > > On the other hand not marking the DMA caches still seems questionable. > > My understanding is that exposing DMA memory to userspace copies can > lead to unexpected results, especially for misbehaving hardware, so I'm > not convinced this is a generically bad hardening choice. "DMA" memory (and thus DMA caches) have nothing to do with DMA. Its a legacy term. "DMA Memory" is memory limited to a certain physical address boundary (old restrictions on certain devices only supporting a limited number of address bits). DMA can be done to NORMAL memory as well.
