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>

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 7be47d1..7233bd7 100644 (file)
--- 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: