linux-kernel - [PATCH 1/5] x86/microcode: Rip out the subsys interface gunk

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Message-Id: <20221019175426.31025-1-bp@alien8.de>
Date:   Wed, 19 Oct 2022 19:54:22 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Ashok Raj <ashok.raj@...el.com>
Cc:     Tony Luck <tony.luck@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Arjan van de Ven <arjan.van.de.ven@...el.com>,
        Jacob Jun Pan <jacob.jun.pan@...el.com>,
        X86 ML <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/5] x86/microcode: Rip out the subsys interface gunk

From: Borislav Petkov <bp@...e.de>

This is a left-over from the old days when CPU hotplug wasn't as robust
as it is now. Currently, microcode gets loaded early on the CPU init
path and there's no need to attempt to load it again.

The only thing that the subsys interface init path was doing is adding
the

  /sys/devices/system/cpu/cpu*/microcode/

hierarchy.

So add a function which gets called on each CPU after all the necessary
driver setup has happened.

Signed-off-by: Borislav Petkov <bp@...e.de>
---
 arch/x86/kernel/cpu/microcode/core.c | 80 ++++++++--------------------
 1 file changed, 22 insertions(+), 58 deletions(-)

diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index 6a41cee242f6..a3aedc93afd9 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -601,8 +601,8 @@ static enum ucode_state microcode_resume_cpu(int cpu)
 
 static enum ucode_state microcode_init_cpu(int cpu, bool refresh_fw)
 {
-	enum ucode_state ustate;
 	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
+	enum ucode_state ustate;
 
 	if (uci->valid)
 		return UCODE_OK;
@@ -636,44 +636,6 @@ static enum ucode_state microcode_update_cpu(int cpu)
 	return microcode_init_cpu(cpu, false);
 }
 
-static int mc_device_add(struct device *dev, struct subsys_interface *sif)
-{
-	int err, cpu = dev->id;
-
-	if (!cpu_online(cpu))
-		return 0;
-
-	pr_debug("CPU%d added\n", cpu);
-
-	err = sysfs_create_group(&dev->kobj, &mc_attr_group);
-	if (err)
-		return err;
-
-	if (microcode_init_cpu(cpu, true) == UCODE_ERROR)
-		return -EINVAL;
-
-	return err;
-}
-
-static void mc_device_remove(struct device *dev, struct subsys_interface *sif)
-{
-	int cpu = dev->id;
-
-	if (!cpu_online(cpu))
-		return;
-
-	pr_debug("CPU%d removed\n", cpu);
-	microcode_fini_cpu(cpu);
-	sysfs_remove_group(&dev->kobj, &mc_attr_group);
-}
-
-static struct subsys_interface mc_cpu_interface = {
-	.name			= "microcode",
-	.subsys			= &cpu_subsys,
-	.add_dev		= mc_device_add,
-	.remove_dev		= mc_device_remove,
-};
-
 /**
  * microcode_bsp_resume - Update boot CPU microcode during resume.
  */
@@ -713,6 +675,9 @@ static int mc_cpu_down_prep(unsigned int cpu)
 	struct device *dev;
 
 	dev = get_cpu_device(cpu);
+
+	microcode_fini_cpu(cpu);
+
 	/* Suspend is in progress, only remove the interface */
 	sysfs_remove_group(&dev->kobj, &mc_attr_group);
 	pr_debug("CPU%d removed\n", cpu);
@@ -720,6 +685,18 @@ static int mc_cpu_down_prep(unsigned int cpu)
 	return 0;
 }
 
+static void setup_online_cpu(void *info)
+{
+	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);
+
+	mc_cpu_online(cpu);
+}
+
 static struct attribute *cpu_root_microcode_attrs[] = {
 #ifdef CONFIG_MICROCODE_LATE_LOADING
 	&dev_attr_reload.attr,
@@ -755,23 +732,19 @@ static int __init microcode_init(void)
 	if (IS_ERR(microcode_pdev))
 		return PTR_ERR(microcode_pdev);
 
-	cpus_read_lock();
-	mutex_lock(&microcode_mutex);
-	error = subsys_interface_register(&mc_cpu_interface);
-	mutex_unlock(&microcode_mutex);
-	cpus_read_unlock();
-
-	if (error)
-		goto out_pdev;
-
 	error = sysfs_create_group(&cpu_subsys.dev_root->kobj,
 				   &cpu_root_microcode_group);
 
 	if (error) {
 		pr_err("Error creating microcode group!\n");
-		goto out_driver;
+		goto out_pdev;
 	}
 
+	/* Do per-CPU setup */
+	cpus_read_lock();
+	on_each_cpu(setup_online_cpu, NULL, 0);
+	cpus_read_unlock();
+
 	register_syscore_ops(&mc_syscore_ops);
 	cpuhp_setup_state_nocalls(CPUHP_AP_MICROCODE_LOADER, "x86/microcode:starting",
 				  mc_cpu_starting, NULL);
@@ -782,15 +755,6 @@ static int __init microcode_init(void)
 
 	return 0;
 
- out_driver:
-	cpus_read_lock();
-	mutex_lock(&microcode_mutex);
-
-	subsys_interface_unregister(&mc_cpu_interface);
-
-	mutex_unlock(&microcode_mutex);
-	cpus_read_unlock();
-
  out_pdev:
 	platform_device_unregister(microcode_pdev);
 	return error;
-- 
2.35.1