Re: [PATCHv3 07/17] x86/mm: Preserve KeyID on pte_modify() and pgprot_modify()

Dave Hansen
2018-06-15T16:58:30Z

On 06/15/2018 09:06 AM, Kirill A. Shutemov wrote:
> I have no idea what such concept should be called. I cannot come with
> anything better than PTE_PFN_MASK_MAX. Do you?

PTE_PRESERVE_MASK

Or maybe:

PTE_MODIFY_PRESERVE_MASK

Maybe a comment to go along with it:

/*
* These are the bits that must be preserved during when doing a
* PTE permission modification operation, like taking a PTE from
* R/W->R/O. They include the physical address and the memory
* encryption keyID. The paddr and the keyID never occupy the same
* bits at the same time. But, a given bit might be used for the keyID
* on one system and used for the physical address on another. As an
* optimization, we manage them in one unit here since their combination
* always occupies the same hardware bits.
*/