On Mon, Jun 20, 2022 at 9:39 AM Federico Di Pierro <nierro92@xxxxxxxxx> wrote: > > Why does your driver need to use that macro? pgprot_encrypted() is > > mostly only directly used by core kernel code, not by drivers... and > > if memory encryption is enabled, almost all memory mappings created by > > the kernel should be marked as encrypted automatically. > > This is interesting; i don't really know the history behind our piece > of code; as far as i understand, > we have a shared ring buffer with userspace, onto which we push tracing events, > and we must mark it as encrypted when > the kmod runs on an AMD SME enabled kernel to allow userspace to grab sane data. > > This is the commit that introduced the change (if you wish to give it a look): > https://github.com/falcosecurity/libs/commit/0333501cf429c045c61aaf5909812156f090786e > > Do you see any workaround not involving `pgprot_encrypted` ? If you do have to use remap_pfn_range() to map normal kernel memory, then you might want to use vma->vm_page_prot instead, like a few other places in the kernel do. (Alternatively you might want to use remap_vmalloc_range() to map vmalloc pages into userspace, but note that that has very different semantics - I believe that installs a normal page reference rather than a raw PFN reference, so that would permit get_user_pages() calls on the range.)
