Hi, On Fri, Apr 20, 2018 at 03:20:19PM -0700, Dave Hansen wrote: > 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. > > The TLB flushing code inside pageattr.c has has checks like > BUG_ON(irqs_disabled()), looking for interrupt disabling that might > cause deadlocks. But, these also trip in early boot on certain > preempt configurations. Just copy the existing BUG_ON() sequence from > cpa_flush_range() to the other two sites and 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]>
Tested-by: Aaro Koskinen <[email protected]> A. > 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 2018-04-20 > 14:10:01.086749169 -0700 > +++ b/arch/x86/mm/pageattr.c 2018-04-20 14:10:01.090749169 -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); > > _
