releases/4.8.5/powerpc-mm-hash64-fix-might_have_hea-check.patch

   1 From 08bf75ba852ef8304a84b6a030466b4b4850382e Mon Sep 17 00:00:00 2001
   2 From: Michael Ellerman <mpe@ellerman.id.au>
   3 Date: Tue, 11 Oct 2016 21:15:04 +1100
   4 Subject: powerpc/mm/hash64: Fix might_have_hea() check
   5
   6 From: Michael Ellerman <mpe@ellerman.id.au>
   7
   8 commit 08bf75ba852ef8304a84b6a030466b4b4850382e upstream.
   9
  10 In commit 2b4e3ad8f579 ("powerpc/mm/hash64: Don't test for machine type
  11 to detect HEA special case") we changed the logic in might_have_hea()
  12 to check FW_FEATURE_SPLPAR rather than machine_is(pseries).
  13
  14 However the check was incorrectly negated, leading to crashes on
  15 machines with HEA adapters, such as:
  16
  17   mm: Hashing failure ! EA=0xd000080080004040 access=0x800000000000000e current=NetworkManager
  18       trap=0x300 vsid=0x13d349c ssize=1 base psize=2 psize 2 pte=0xc0003cc033e701ae
  19   Unable to handle kernel paging request for data at address 0xd000080080004040
  20   Call Trace:
  21     .ehea_create_cq+0x148/0x340 [ehea] (unreliable)
  22     .ehea_up+0x258/0x1200 [ehea]
  23     .ehea_open+0x44/0x1a0 [ehea]
  24     ...
  25
  26 Fix it by removing the negation.
  27
  28 Fixes: 2b4e3ad8f579 ("powerpc/mm/hash64: Don't test for machine type to detect HEA special case")
  29 Reported-by: Denis Kirjanov <kda@linux-powerpc.org>
  30 Reported-by: Jan Stancek <jstancek@redhat.com>
  31 Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
  32 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  33
  34 ---
  35  arch/powerpc/mm/hash_utils_64.c |    2 +-
  36  1 file changed, 1 insertion(+), 1 deletion(-)
  37
  38 --- a/arch/powerpc/mm/hash_utils_64.c
  39 +++ b/arch/powerpc/mm/hash_utils_64.c
  40 @@ -526,7 +526,7 @@ static bool might_have_hea(void)
  41          */
  42  #ifdef CONFIG_IBMEBUS
  43         return !cpu_has_feature(CPU_FTR_ARCH_207S) &&
  44 -               !firmware_has_feature(FW_FEATURE_SPLPAR);
  45 +               firmware_has_feature(FW_FEATURE_SPLPAR);
  46  #else
  47         return false;
  48  #endif