[4.2.y-ckt stable] Patch "powerpc: Update TM user feature bits in scan_features()" has been added to the 4.2.y-ckt tree

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    powerpc: Update TM user feature bits in scan_features()

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt9.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

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

>From 00daaa096922ed7377175168d305f68390f04193 Mon Sep 17 00:00:00 2001
From: Anton Blanchard <anton at samba.org>
Date: Fri, 15 Apr 2016 12:08:19 +1000
Subject: powerpc: Update TM user feature bits in scan_features()

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 at samba.org>
Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
Signed-off-by: Kamal Mostafa <kamal at canonical.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 a7787a7..c275616 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -161,11 +161,12 @@ 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