linux-kernel - [PATCH 4.17 058/220] powerpc/64s: Fix DT CPU features Power9 DD2.1 logic

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Date:   Sun,  1 Jul 2018 18:21:22 +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, Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>
Subject: [PATCH 4.17 058/220] powerpc/64s: Fix DT CPU features Power9 DD2.1 logic

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

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

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

commit 749a0278c2177b2d16da5d8b135ba7f940bb4199 upstream.

In the device tree CPU features quirk code we want to set
CPU_FTR_POWER9_DD2_1 on all Power9s that aren't DD2.0 or earlier. But
we got the logic wrong and instead set it on all CPUs that aren't
Power9 DD2.0 or earlier, ie. including Power8.

Fix it by making sure we're on a Power9. This isn't a bug in practice
because the only code that checks the feature is Power9 only to begin
with. But we'll backport it anyway to avoid confusion.

Fixes: 9e9626ed3a4a ("powerpc/64s: Fix POWER9 DD2.2 and above in DT CPU features")
Cc: stable@...r.kernel.org # v4.17+
Reported-by: Paul Mackerras <paulus@...ba.org>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Acked-by: Nicholas Piggin <npiggin@...il.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/powerpc/kernel/dt_cpu_ftrs.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/arch/powerpc/kernel/dt_cpu_ftrs.c
+++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
@@ -711,7 +711,8 @@ static __init void cpufeatures_cpu_quirk
 		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TM_HV_ASSIST;
 		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TM_XER_SO_BUG;
 		cur_cpu_spec->cpu_features |= CPU_FTR_POWER9_DD2_1;
-	} else /* DD2.1 and up have DD2_1 */
+	} else if ((version & 0xffff0000) == 0x004e0000)
+		/* DD2.1 and up have DD2_1 */
 		cur_cpu_spec->cpu_features |= CPU_FTR_POWER9_DD2_1;
 
 	if ((version & 0xffff0000) == 0x004e0000) {