Commit ddac3d8b authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'x86_urgent_for_v6.8_rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 fix from Borislav Petkov:

 - Use a GB page for identity mapping only when memory of this size is
   requested so that mapping of reserved regions is prevented which
   would otherwise lead to system crashes on UV machines

* tag 'x86_urgent_for_v6.8_rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mm/ident_map: Use gbpages only where full GB page should be mapped.
parents 7cb7c32d d794734c

arch/x86/mm/ident_map.c

+18 −5
Original line number Diff line number Diff line
@@ -26,18 +26,31 @@ static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page, 
	for (; addr < end; addr = next) {

		pud_t *pud = pud_page + pud_index(addr);

		pmd_t *pmd;

		bool use_gbpage;



		next = (addr & PUD_MASK) + PUD_SIZE;

		if (next > end)

			next = end;



		if (info->direct_gbpages) {

			pud_t pudval;



			if (pud_present(*pud))

		/* if this is already a gbpage, this portion is already mapped */

		if (pud_large(*pud))

			continue;



			addr &= PUD_MASK;

		/* Is using a gbpage allowed? */

		use_gbpage = info->direct_gbpages;



		/* Don't use gbpage if it maps more than the requested region. */

		/* at the begining: */

		use_gbpage &= ((addr & ~PUD_MASK) == 0);

		/* ... or at the end: */

		use_gbpage &= ((next & ~PUD_MASK) == 0);



		/* Never overwrite existing mappings */

		use_gbpage &= !pud_present(*pud);



		if (use_gbpage) {

			pud_t pudval;



			pudval = __pud((addr - info->offset) | info->page_flag);

			set_pud(pud, pudval);

			continue;