These are _very_ lightly tested. I'm throwing them out there for folks are looking for a fix.
--- From: Dave Hansen <[email protected]> Part of the global bit _setting_ patches also includes clearing the Global bit when we do not want it. That is done with set_memory_nonglobal(), which uses change_page_attr_clear() in pageattr.c under the covers. However, it's pretty clear that change_page_attr_clear() has not been heavily used early in boot, or on kernel text. It has checks like BUG_ON(irqs_disabled()), looking for interrupt disabling but that also trip in early boot on certain preempt configurations. Just copy the existing BUG_ON() sequence to check for early boot. Signed-off-by: Dave Hansen <[email protected]> Fixes: 39114b7a7 (x86/pti: Never implicitly clear _PAGE_GLOBAL for kernel image) Reported-by: Mariusz Ceier <[email protected]> Reported-by: Aaro Koskinen <[email protected]> Cc: Andrea Arcangeli <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Arjan van de Ven <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Dan Williams <[email protected]> Cc: David Woodhouse <[email protected]> Cc: Greg Kroah-Hartman <[email protected]> Cc: Hugh Dickins <[email protected]> Cc: Josh Poimboeuf <[email protected]> Cc: Juergen Gross <[email protected]> Cc: Kees Cook <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Nadav Amit <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] --- b/arch/x86/mm/pageattr.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff -puN arch/x86/mm/pageattr.c~pti-glb-boot-problem-fix arch/x86/mm/pageattr.c --- a/arch/x86/mm/pageattr.c~pti-glb-boot-problem-fix 2018-04-17 14:10:13.553395577 -0700 +++ b/arch/x86/mm/pageattr.c 2018-04-17 14:10:13.559395577 -0700 @@ -172,7 +172,7 @@ static void __cpa_flush_all(void *arg) static void cpa_flush_all(unsigned long cache) { - BUG_ON(irqs_disabled()); + BUG_ON(irqs_disabled() && !early_boot_irqs_disabled); on_each_cpu(__cpa_flush_all, (void *) cache, 1); } @@ -236,7 +236,7 @@ static void cpa_flush_array(unsigned lon unsigned long do_wbinvd = cache && numpages >= 1024; /* 4M threshold */ #endif - BUG_ON(irqs_disabled()); + BUG_ON(irqs_disabled() && !early_boot_irqs_disabled); on_each_cpu(__cpa_flush_all, (void *) do_wbinvd, 1); _
