[patch 17/60] x86: work around Fedora-11 x86-32 kernel failures on Intel Atom CPUs

[Greg KH]

-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Ingo Molnar <mingo@xxxxxxx>
commit 211b3d03c7400f48a781977a50104c9d12f4e229 upstream

[Trivial backport to 2.6.27 by cebbert@xxxxxxxxxx]

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@xxxxxxxxxxxxxxxxxxxx>
Tested-by: Kyle McMartin <kyle@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Cc: <cebbert@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---

---
 arch/x86/mm/pageattr.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -565,6 +565,17 @@ static int split_large_page(pte_t *kpte,
 	ref_prot = pte_pgprot(pte_mkexec(pte_clrhuge(*kpte)));
 	pgprot_val(ref_prot) |= _PAGE_PRESENT;
 	__set_pmd_pte(kpte, address, mk_pte(base, ref_prot));
+
+	/*
+	 * 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:


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