linux-kernel - [patch V4 15/30] x86/microcode: Remove pointless apply() invocation

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Date:   Mon,  2 Oct 2023 13:59:52 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, Borislav Petkov <bp@...en8.de>,
        "Chang S. Bae" <chang.seok.bae@...el.com>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        Nikolay Borisov <nik.borisov@...e.com>
Subject: [patch V4 15/30] x86/microcode: Remove pointless apply() invocation

Microcode is applied on the APs during early bringup. There is no point in
trying to apply the microcode again during the hotplug operations and
neither at the point where the microcode device is initialized.

Collect CPU info and microcode revision in setup_online_cpu() for now. This
will move to the CPU hotplug callback in the next step.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
V2: New patch
---
 arch/x86/kernel/cpu/microcode/core.c |   34 ++++++----------------------------
 include/linux/cpuhotplug.h           |    1 -
 2 files changed, 6 insertions(+), 29 deletions(-)

--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -490,17 +490,6 @@ static void microcode_fini_cpu(int cpu)
 		microcode_ops->microcode_fini_cpu(cpu);
 }
 
-static enum ucode_state microcode_init_cpu(int cpu)
-{
-	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
-
-	memset(uci, 0, sizeof(*uci));
-
-	microcode_ops->collect_cpu_info(cpu, &uci->cpu_sig);
-
-	return microcode_ops->apply_microcode(cpu);
-}
-
 /**
  * microcode_bsp_resume - Update boot CPU microcode during resume.
  */
@@ -519,15 +508,6 @@ static struct syscore_ops mc_syscore_ops
 	.resume	= microcode_bsp_resume,
 };
 
-static int mc_cpu_starting(unsigned int cpu)
-{
-	enum ucode_state err = microcode_ops->apply_microcode(cpu);
-
-	pr_debug("%s: CPU%d, err: %d\n", __func__, cpu, err);
-
-	return err == UCODE_ERROR;
-}
-
 static int mc_cpu_online(unsigned int cpu)
 {
 	struct device *dev = get_cpu_device(cpu);
@@ -555,14 +535,14 @@ static int mc_cpu_down_prep(unsigned int
 static void setup_online_cpu(struct work_struct *work)
 {
 	int cpu = smp_processor_id();
-	enum ucode_state err;
+	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
 
-	err = microcode_init_cpu(cpu);
-	if (err == UCODE_ERROR) {
-		pr_err("Error applying microcode on CPU%d\n", cpu);
-		return;
-	}
+	memset(uci, 0, sizeof(*uci));
 
+	microcode_ops->collect_cpu_info(cpu, &uci->cpu_sig);
+	cpu_data(cpu).microcode = uci->cpu_sig.rev;
+	if (!cpu)
+		boot_cpu_data.microcode = uci->cpu_sig.rev;
 	mc_cpu_online(cpu);
 }
 
@@ -615,8 +595,6 @@ static int __init microcode_init(void)
 	schedule_on_each_cpu(setup_online_cpu);
 
 	register_syscore_ops(&mc_syscore_ops);
-	cpuhp_setup_state_nocalls(CPUHP_AP_MICROCODE_LOADER, "x86/microcode:starting",
-				  mc_cpu_starting, NULL);
 	cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/microcode:online",
 				  mc_cpu_online, mc_cpu_down_prep);
 
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -156,7 +156,6 @@ enum cpuhp_state {
 	CPUHP_AP_IRQ_LOONGARCH_STARTING,
 	CPUHP_AP_IRQ_SIFIVE_PLIC_STARTING,
 	CPUHP_AP_ARM_MVEBU_COHERENCY,
-	CPUHP_AP_MICROCODE_LOADER,
 	CPUHP_AP_PERF_X86_AMD_UNCORE_STARTING,
 	CPUHP_AP_PERF_X86_STARTING,
 	CPUHP_AP_PERF_X86_AMD_IBS_STARTING,