Hi Dave,

On 7/8/21 5:38 PM, Andi Kleen wrote:

quoted

Expensive and permanently fractures the direct map.

I'm struggling to figure out why the direct map is even touched here.

I think Sathya did it this way because the TD interface requires a physical address.

quoted

Why not just use a vmalloc area mapping?  You really just need *a*
decrypted mapping to the page.  You don't need to make *every* mapping
to the page decrypted.

Yes it would be possible to use vmap() on the page and only set the vmap encrypted by passing the 
right flags directly.

Is it alright to have non coherent mappings? If yes, any documentation reference for it?

That would avoid breaking up the direct mapping.

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer