linux-kernel - [patch 10/30] x86/microcode: Remove pointless mutex

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Message-ID: <20230810160805.542014725@linutronix.de>
Date:   Thu, 10 Aug 2023 20:37:40 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, Borislav Petkov <bp@...en8.de>,
        Ashok Raj <ashok.raj@...el.com>,
        Arjan van de Ven <arjan@...ux.intel.com>
Subject: [patch 10/30] x86/microcode: Remove pointless mutex

From: Thomas Gleixner <tglx@...utronix.de>

There is no concurreny.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

---
 arch/x86/kernel/cpu/microcode/intel.c |   24 ++----------------------
 1 file changed, 2 insertions(+), 22 deletions(-)
---
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -302,22 +302,6 @@ scan_microcode(void *data, size_t size,
 	return patch;
 }
 
-/*
- * Save this microcode patch. It will be loaded early when a CPU is
- * hot-added or resumes.
- */
-static void save_mc_for_early(struct ucode_cpu_info *uci, u8 *mc, unsigned int size)
-{
-	/* Synchronization during CPU hotplug. */
-	static DEFINE_MUTEX(x86_cpu_microcode_mutex);
-
-	mutex_lock(&x86_cpu_microcode_mutex);
-
-	save_microcode_patch(mc, size);
-
-	mutex_unlock(&x86_cpu_microcode_mutex);
-}
-
 static bool load_builtin_intel_microcode(struct cpio_data *cp)
 {
 	unsigned int eax = 1, ebx, ecx = 0, edx;
@@ -718,12 +702,8 @@ static enum ucode_state generic_load_mic
 	vfree(uci->mc);
 	uci->mc = (struct microcode_intel *)new_mc;
 
-	/*
-	 * If early loading microcode is supported, save this mc into
-	 * permanent memory. So it will be loaded early when a CPU is hot added
-	 * or resumes.
-	 */
-	save_mc_for_early(uci, new_mc, new_mc_size);
+	/* Save for CPU hotplug */
+	save_microcode_patch(new_mc, new_mc_size);
 
 	pr_debug("CPU%d found a matching microcode update with version 0x%x (current=0x%x)\n",
 		 cpu, new_rev, uci->cpu_sig.rev);