linux-kernel - [PATCH 4.8 046/140] powerpc/mm/hash64: Fix might_have

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Date:   Wed, 26 Oct 2016 14:21:46 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        Jan Stancek <jstancek@...hat.com>,
        Michael Ellerman <mpe@...erman.id.au>
Subject: [PATCH 4.8 046/140] powerpc/mm/hash64: Fix might_have_hea() check

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

------------------

From: Michael Ellerman <mpe@...erman.id.au>

commit 08bf75ba852ef8304a84b6a030466b4b4850382e upstream.

In commit 2b4e3ad8f579 ("powerpc/mm/hash64: Don't test for machine type
to detect HEA special case") we changed the logic in might_have_hea()
to check FW_FEATURE_SPLPAR rather than machine_is(pseries).

However the check was incorrectly negated, leading to crashes on
machines with HEA adapters, such as:

  mm: Hashing failure ! EA=0xd000080080004040 access=0x800000000000000e current=NetworkManager
      trap=0x300 vsid=0x13d349c ssize=1 base psize=2 psize 2 pte=0xc0003cc033e701ae
  Unable to handle kernel paging request for data at address 0xd000080080004040
  Call Trace:
    .ehea_create_cq+0x148/0x340 [ehea] (unreliable)
    .ehea_up+0x258/0x1200 [ehea]
    .ehea_open+0x44/0x1a0 [ehea]
    ...

Fix it by removing the negation.

Fixes: 2b4e3ad8f579 ("powerpc/mm/hash64: Don't test for machine type to detect HEA special case")
Reported-by: Denis Kirjanov <kda@...ux-powerpc.org>
Reported-by: Jan Stancek <jstancek@...hat.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/powerpc/mm/hash_utils_64.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -526,7 +526,7 @@ static bool might_have_hea(void)
 	 */
 #ifdef CONFIG_IBMEBUS
 	return !cpu_has_feature(CPU_FTR_ARCH_207S) &&
-		!firmware_has_feature(FW_FEATURE_SPLPAR);
+		firmware_has_feature(FW_FEATURE_SPLPAR);
 #else
 	return false;
 #endif