linux-kernel - [PATCH 3.19.y-ckt 44/66] powerpc: Update TM user feature bits in scan

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Message-Id: <1461702297-7792-45-git-send-email-kamal@canonical.com>
Date:	Tue, 26 Apr 2016 13:24:35 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Anton Blanchard <anton@...ba.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.19.y-ckt 44/66] powerpc: Update TM user feature bits in scan_features()

3.19.8-ckt20 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Anton Blanchard <anton@...ba.org>

commit 4705e02498d6d5a7ab98dfee9595cd5e91db2017 upstream.

We need to update the user TM feature bits (PPC_FEATURE2_HTM and
PPC_FEATURE2_HTM) to mirror what we do with the kernel TM feature
bit.

At the moment, if firmware reports TM is not available we turn off
the kernel TM feature bit but leave the userspace ones on. Userspace
thinks it can execute TM instructions and it dies trying.

This (together with a QEMU patch) fixes PR KVM, which doesn't currently
support TM.

Signed-off-by: Anton Blanchard <anton@...ba.org>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 arch/powerpc/kernel/prom.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index 6d198c1..46b5ecf 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -162,11 +162,12 @@ static struct ibm_pa_feature {
 	{0, MMU_FTR_CI_LARGE_PAGE, 0, 0,		1, 2, 0},
 	{CPU_FTR_REAL_LE, 0, PPC_FEATURE_TRUE_LE, 0, 5, 0, 0},
 	/*
-	 * If the kernel doesn't support TM (ie. CONFIG_PPC_TRANSACTIONAL_MEM=n),
-	 * we don't want to turn on CPU_FTR_TM here, so we use CPU_FTR_TM_COMP
-	 * which is 0 if the kernel doesn't support TM.
+	 * If the kernel doesn't support TM (ie CONFIG_PPC_TRANSACTIONAL_MEM=n),
+	 * we don't want to turn on TM here, so we use the *_COMP versions
+	 * which are 0 if the kernel doesn't support TM.
 	 */
-	{CPU_FTR_TM_COMP, 0, 0, 0,		22, 0, 0},
+	{CPU_FTR_TM_COMP, 0, 0,
+	 PPC_FEATURE2_HTM_COMP|PPC_FEATURE2_HTM_NOSC_COMP, 22, 0, 0},
 };
 
 static void __init scan_features(unsigned long node, const unsigned char *ftrs,
-- 
2.7.4