Re: [PATCH, RFC 44/62] x86/mm: Set KeyIDs in encrypted VMAs for MKTME

[Peter Zijlstra]

On Wed, May 08, 2019 at 05:44:04PM +0300, Kirill A. Shutemov wrote:
> From: Alison Schofield <alison.schofield@xxxxxxxxx>
> 
> MKTME architecture requires the KeyID to be placed in PTE bits 51:46.
> To create an encrypted VMA, place the KeyID in the upper bits of
> vm_page_prot that matches the position of those PTE bits.
> 
> When the VMA is assigned a KeyID it is always considered a KeyID
> change. The VMA is either going from not encrypted to encrypted,
> or from encrypted with any KeyID to encrypted with any other KeyID.
> To make the change safely, remove the user pages held by the VMA
> and unlink the VMA's anonymous chain.

This does not look like a transformation that preserves content; is
mprotect() still a suitable name?