linux-kernel - [PATCH 3.16 75/86] x86/speculation: Move arch_smt_update() call to after mitigation decisions

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Message-ID: <lsq.1558022133.413450664@decadent.org.uk>
Date:   Thu, 16 May 2019 16:55:33 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Tyler Hicks" <tyhicks@...onical.com>,
        "Jiri Kosina" <jkosina@...e.cz>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        "Josh Poimboeuf" <jpoimboe@...hat.com>
Subject: [PATCH 3.16 75/86] x86/speculation: Move arch_smt_update() call
 to after mitigation decisions

3.16.68-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Josh Poimboeuf <jpoimboe@...hat.com>

commit 7c3658b20194a5b3209a143f63bc9c643c6a3ae2 upstream.

arch_smt_update() now has a dependency on both Spectre v2 and MDS
mitigations.  Move its initial call to after all the mitigation decisions
have been made.

Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Tyler Hicks <tyhicks@...onical.com>
Acked-by: Jiri Kosina <jkosina@...e.cz>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/x86/kernel/cpu/bugs.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -161,6 +161,8 @@ void __init check_bugs(void)
 
 	mds_select_mitigation();
 
+	arch_smt_update();
+
 #ifdef CONFIG_X86_32
 	/*
 	 * Check whether we are able to run this kernel safely on SMP.
@@ -677,9 +679,6 @@ specv2_set_mode:
 
 	/* Set up IBPB and STIBP depending on the general spectre V2 command */
 	spectre_v2_user_select_mitigation(cmd);
-
-	/* Enable STIBP if appropriate */
-	arch_smt_update();
 }
 
 static void update_stibp_msr(void * __unused)