Re: [PATCHv6 02/15] mm: Add support for unaccepted memory

[Kirill A. Shutemov]

On Tue, May 17, 2022 at 10:45:16AM -0700, Andrew Morton wrote:
> On Tue, 17 May 2022 18:34:31 +0300 "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> wrote:
> 
> > UEFI Specification version 2.9 introduces the concept of memory
> > acceptance. Some Virtual Machine platforms, such as Intel TDX or AMD
> > SEV-SNP, require memory to be accepted before it can be used by the
> > guest. Accepting happens via a protocol specific to the Virtual Machine
> > platform.
> > 
> > ...
> >
> > --- a/include/linux/page-flags.h
> > +++ b/include/linux/page-flags.h
> > @@ -928,6 +928,14 @@ static inline bool is_page_hwpoison(struct page *page)
> >  #define PG_offline	0x00000100
> >  #define PG_table	0x00000200
> >  #define PG_guard	0x00000400
> > +#define PG_unaccepted	0x00000800
> 
> "For pages that are never mapped to userspace (and aren't PageSlab),
> page_type may be used."
> 
> Is that true of these pages?

Yes. PG_unaccepted is never set for any allocated page. It is only set for
pages on free lists. It gets cleared in post_alloc_hook().

-- 
 Kirill A. Shutemov