linux-kernel - [PATCH 4.17 109/336] x86/microcode: Make the late update update

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Date:   Wed,  1 Aug 2018 18:47:24 +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, Scott Wood <swood@...hat.com>,
        Borislav Petkov <bp@...e.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ashok Raj <ashok.raj@...el.com>,
        Clark Williams <williams@...hat.com>,
        Pei Zhang <pezhang@...hat.com>, x86-ml <x86@...nel.org>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.17 109/336] x86/microcode: Make the late update update_lock a raw lock for RT

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

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

From: Scott Wood <swood@...hat.com>

[ Upstream commit ff987fcf011d20c53b3a613edf6e2055ea48e26e ]

__reload_late() is called from stop_machine context and thus cannot
acquire a non-raw spinlock on PREEMPT_RT.

Signed-off-by: Scott Wood <swood@...hat.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Acked-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Ashok Raj <ashok.raj@...el.com>
Cc: Clark Williams <williams@...hat.com>
Cc: Pei Zhang <pezhang@...hat.com>
Cc: x86-ml <x86@...nel.org>
Link: http://lkml.kernel.org/r/20180524154420.24455-1-swood@redhat.com
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/kernel/cpu/microcode/core.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -70,7 +70,7 @@ static DEFINE_MUTEX(microcode_mutex);
 /*
  * Serialize late loading so that CPUs get updated one-by-one.
  */
-static DEFINE_SPINLOCK(update_lock);
+static DEFINE_RAW_SPINLOCK(update_lock);
 
 struct ucode_cpu_info		ucode_cpu_info[NR_CPUS];
 
@@ -560,9 +560,9 @@ static int __reload_late(void *info)
 	if (__wait_for_cpus(&late_cpus_in, NSEC_PER_SEC))
 		return -1;
 
-	spin_lock(&update_lock);
+	raw_spin_lock(&update_lock);
 	apply_microcode_local(&err);
-	spin_unlock(&update_lock);
+	raw_spin_unlock(&update_lock);
 
 	/* siblings return UCODE_OK because their engine got updated already */
 	if (err > UCODE_NFOUND) {