Patch "x86/CPU: Add a microcode loader callback" has been added to the 4.15-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    x86/CPU: Add a microcode loader callback

to the 4.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     x86-cpu-add-a-microcode-loader-callback.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>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

From: Borislav Petkov <bp@suse.de>

commit 1008c52c09dcb23d93f8e0ea83a6246265d2cce0 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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(-)

--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -969,4 +969,5 @@ 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 */
--- 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();
+}
--- 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 devic
 			    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 devic
 			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();


Patches currently in stable-queue which might be from bp@suse.de are

queue-4.15/x86-microcode-intel-check-microcode-revision-before-updating-sibling-threads.patch
queue-4.15/x86-microcode-attempt-late-loading-only-when-new-microcode-is-present.patch
queue-4.15/x86-microcode-propagate-return-value-from-updating-functions.patch
queue-4.15/x86-cpu-check-cpu-feature-bits-after-microcode-upgrade.patch
queue-4.15/x86-microcode-intel-writeback-and-invalidate-caches-before-updating-microcode.patch
queue-4.15/x86-microcode-intel-look-into-the-patch-cache-first.patch
queue-4.15/edac-mv64x60-fix-an-error-handling-path.patch
queue-4.15/x86-microcode-request-microcode-on-the-bsp.patch
queue-4.15/x86-microcode-get-rid-of-struct-apply_microcode_ctx.patch
queue-4.15/x86-microcode-fix-cpu-synchronization-routine.patch
queue-4.15/x86-microcode-synchronize-late-microcode-loading.patch
queue-4.15/x86-microcode-do-not-upload-microcode-if-cpus-are-offline.patch
queue-4.15/x86-cpu-add-a-microcode-loader-callback.patch