On Thu, Jan 11, 2018 at 04:58:20PM -0500, Pavel Tatashin wrote: > The page table order must be increased for EFI table in order to avoid a > bug where NMI tries to change the page table to kernel page table, while > efi page table is active. > > For more disccussion about this bug, see this thread: > http://lkml.iu.edu/hypermail/linux/kernel/1801.1/00951.html > > Signed-off-by: Pavel Tatashin <[email protected]> > Reviewed-by: Steven Sistare <[email protected]> > Acked-by: Jiri Kosina <[email protected]> > --- > arch/x86/include/asm/pgalloc.h | 11 +++++++++++ > arch/x86/platform/efi/efi_64.c | 2 +- > 2 files changed, 12 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/include/asm/pgalloc.h b/arch/x86/include/asm/pgalloc.h > index b6d425999f99..1178a51b77f3 100644 > --- a/arch/x86/include/asm/pgalloc.h > +++ b/arch/x86/include/asm/pgalloc.h > @@ -27,6 +27,17 @@ static inline void paravirt_release_pud(unsigned long pfn) > {} > */ > extern gfp_t __userpte_alloc_gfp; > > +#ifdef CONFIG_PAGE_TABLE_ISOLATION > +/* > + * Instead of one PGD, we acquire two PGDs. Being order-1, it is > + * both 8k in size and 8k-aligned. That lets us just flip bit 12 > + * in a pointer to swap between the two 4k halves. > + */ > +#define PGD_ALLOCATION_ORDER 1 > +#else > +#define PGD_ALLOCATION_ORDER 0 > +#endif
This conflicts with the definition of PGD_ALLOCATION_ORDER in arch/x86/mm/pgtable.c that says: /* * Instead of one pgd, Kaiser acquires two pgds. Being order-1, it is * both 8k in size and 8k-aligned. That lets us just flip bit 12 * in a pointer to swap between the two 4k halves. */ #define PGD_ALLOCATION_ORDER kaiser_enabled So, which is it? I'm going to go drop this from the 4.9 stable queue because of this. thanks, greg k-h
