On Fri, Jun 15, 2018 at 04:58:24PM +0000, Dave Hansen wrote: > 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 It just replacing one confusion with another. Preserve what? How does it differ from _PAGE_CHG_MASK? I frankly think my name proposal convey more meaning. > 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. > */ Thanks, this is useful. -- Kirill A. Shutemov
