From: Sai Praneeth <[email protected]> Since EFI page tables can be treated as kernel page tables they should be global. All the other page mapping functions in pageattr.c set the _PAGE_GLOBAL bit and we want to avoid inconsistencies when we map a page in the EFI code paths, for example when that page is split in __split_large_page(), etc. It also makes it easier to validate that the EFI region mappings have the correct attributes because there are fewer differences compared with regular kernel mappings.
Cc: Ricardo Neri <[email protected]> Cc: Ravi Shankar <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Matt Fleming <[email protected]> Signed-off-by: Sai Praneeth Prakhya <[email protected]> --- arch/x86/mm/pageattr.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 3052e72fa9f5..9256f6406a3c 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -904,6 +904,20 @@ static void populate_pte(struct cpa_data *cpa, pte = pte_offset_kernel(pmd, start); + /* + * Set the GLOBAL flags only if the PRESENT flag is + * set otherwise pte_present will return true even on + * a non present pte. The canon_pgprot will clear + * _PAGE_GLOBAL for the ancient hardware that doesn't + * support it. + */ + if (pgprot_val(pgprot) & _PAGE_PRESENT) + pgprot_val(pgprot) |= _PAGE_GLOBAL; + else + pgprot_val(pgprot) &= ~_PAGE_GLOBAL; + + pgprot = canon_pgprot(pgprot); + while (num_pages-- && start < end) { set_pte(pte, pfn_pte(cpa->pfn, pgprot)); -- 2.1.4
