x86: work around Fedora-11 x86-32 kernel failures on Intel Atom CPUs

Impact: work around boot crash

Work around Intel Atom erratum AAH41 (probabilistically) - it's triggering
in the field.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Tested-by: Kyle McMartin <kyle@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 11 insertions, 0 deletions

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 7be47d1a97e4..7233bd7e357b 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -515,6 +515,17 @@ static int split_large_page(pte_t *kpte, unsigned long address)
          * primary protection behavior:
          */
         __set_pmd_pte(kpte, address, mk_pte(base, __pgprot(_KERNPG_TABLE)));
+
+        /*
+         * Intel Atom errata AAH41 workaround.
+         *
+         * The real fix should be in hw or in a microcode update, but
+         * we also probabilistically try to reduce the window of having
+         * a large TLB mixed with 4K TLBs while instruction fetches are
+         * going on.
+         */
+        __flush_tlb_all();
+
         base = NULL;
 
 out_unlock: