From 1008c52c09dcb23d93f8e0ea83a6246265d2cce0 Mon Sep 17 00:00:00 2001

From: Borislav Petkov <bp@suse.de>

Date: Fri, 16 Feb 2018 12:26:39 +0100

Subject: x86/CPU: Add a microcode loader callback

Add a callback function which the microcode loader calls when microcode

has been updated to a newer revision. Do the callback only when no error

was encountered during loading.

Tested-by: Ashok Raj <ashok.raj@intel.com>

Signed-off-by: Borislav Petkov <bp@suse.de>

Reviewed-by: Ashok Raj <ashok.raj@intel.com>

Cc: Andy Lutomirski <luto@kernel.org>

Cc: Arjan van de Ven <arjan@linux.intel.com>

Cc: Borislav Petkov <bp@alien8.de>

Cc: Dan Williams <dan.j.williams@intel.com>

Cc: Dave Hansen <dave.hansen@linux.intel.com>

Cc: David Woodhouse <dwmw2@infradead.org>

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Cc: Josh Poimboeuf <jpoimboe@redhat.com>

Cc: Linus Torvalds <torvalds@linux-foundation.org>

Cc: Peter Zijlstra <peterz@infradead.org>

Cc: Thomas Gleixner <tglx@linutronix.de>

Link: http://lkml.kernel.org/r/20180216112640.11554-3-bp@alien8.de

Signed-off-by: Ingo Molnar <mingo@kernel.org>

---

 arch/x86/include/asm/processor.h     |  1 +

 arch/x86/kernel/cpu/common.c         | 10 ++++++++++

 arch/x86/kernel/cpu/microcode/core.c |  8 ++++++--

 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h

index 1bd9ed8..b0ccd48 100644

--- a/arch/x86/include/asm/processor.h

+++ b/arch/x86/include/asm/processor.h

@@ -977,4 +977,5 @@ bool xen_set_default_idle(void);

 void stop_this_cpu(void *dummy);

 void df_debug(struct pt_regs *regs, long error_code);

+void microcode_check(void);

 #endif /* _ASM_X86_PROCESSOR_H */

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c

index 824aee0..84f1cd8 100644

--- a/arch/x86/kernel/cpu/common.c

+++ b/arch/x86/kernel/cpu/common.c

@@ -1749,3 +1749,13 @@ static int __init init_cpu_syscore(void)

 	return 0;

 }

 core_initcall(init_cpu_syscore);

+

+/*

+ * The microcode loader calls this upon late microcode load to recheck features,

+ * only when microcode has been updated. Caller holds microcode_mutex and CPU

+ * hotplug lock.

+ */

+void microcode_check(void)

+{

+	perf_check_microcode();

+}

diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c

index 6fdaf7c..aa1b9a4 100644

--- a/arch/x86/kernel/cpu/microcode/core.c

+++ b/arch/x86/kernel/cpu/microcode/core.c

@@ -509,6 +509,7 @@ static ssize_t reload_store(struct device *dev,

 			    const char *buf, size_t size)

 {

 	enum ucode_state tmp_ret = UCODE_OK;

+	bool do_callback = false;

 	unsigned long val;

 	ssize_t ret = 0;

 	int cpu;

@@ -531,10 +532,13 @@ static ssize_t reload_store(struct device *dev,

 			if (!ret)

 				ret = -EINVAL;

 		}

+

+		if (tmp_ret == UCODE_UPDATED)

+			do_callback = true;

 	}

-	if (!ret && tmp_ret == UCODE_UPDATED)

-		perf_check_microcode();

+	if (!ret && do_callback)

+		microcode_check();

 	mutex_unlock(&microcode_mutex);

 	put_online_cpus();

-- 

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