linux-kernel - [patch V4 16/30] x86/microcode: Get rid of the schedule work indirection

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Date:   Mon,  2 Oct 2023 13:59:54 +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 16/30] x86/microcode: Get rid of the schedule work
 indirection

Scheduling work on all CPUs to collect the microcode information is just
another extra step for no value. Let the CPU hotplug callback registration
do it.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
V2: New patch
---
 arch/x86/kernel/cpu/microcode/core.c |   29 ++++++++++-------------------
 1 file changed, 10 insertions(+), 19 deletions(-)

--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -510,8 +510,16 @@ static struct syscore_ops mc_syscore_ops
 
 static int mc_cpu_online(unsigned int cpu)
 {
+	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
 	struct device *dev = get_cpu_device(cpu);
 
+	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;
+
 	if (sysfs_create_group(&dev->kobj, &mc_attr_group))
 		pr_err("Failed to create group for CPU%d\n", cpu);
 	return 0;
@@ -532,20 +540,6 @@ static int mc_cpu_down_prep(unsigned int
 	return 0;
 }
 
-static void setup_online_cpu(struct work_struct *work)
-{
-	int cpu = smp_processor_id();
-	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
-
-	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);
-}
-
 static struct attribute *cpu_root_microcode_attrs[] = {
 #ifdef CONFIG_MICROCODE_LATE_LOADING
 	&dev_attr_reload.attr,
@@ -591,12 +585,9 @@ static int __init microcode_init(void)
 		}
 	}
 
-	/* Do per-CPU setup */
-	schedule_on_each_cpu(setup_online_cpu);
-
 	register_syscore_ops(&mc_syscore_ops);
-	cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/microcode:online",
-				  mc_cpu_online, mc_cpu_down_prep);
+	cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/microcode:online",
+			  mc_cpu_online, mc_cpu_down_prep);
 
 	pr_info("Microcode Update Driver: v%s.", DRIVER_VERSION);