RE: [PATCH 2/2] x86, microcode: Make reload interface per system

["Yu, Fenghua" <fenghua.yu@xxxxxxxxx>]

> From: Borislav Petkov <bp@xxxxxxxxx>
> Date: Tue, 19 Jun 2012 18:03:31 +0200
> Subject: [PATCH 2/2] x86, microcode: Make reload interface per system
> To: X86-ML <x86@xxxxxxxxxx>
> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>,
> Thomas Gleixner <tglx@xxxxxxxxxxxxx>, LKML
> <linux-kernel@xxxxxxxxxxxxxxx>, Andreas Herrmann
> <andreas.herrmann3@xxxxxxx>, Borislav Petkov
> <borislav.petkov@xxxxxxx>, Henrique de Moraes Holschuh
> <hmh@xxxxxxxxxx>, Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> 
> From: Borislav Petkov <borislav.petkov@xxxxxxx>
> 
> The reload interface should be per-system so that a full system ucode
> reload happens (on each core) when doing
> 
> echo 1 > /sys/devices/system/cpu/microcode/reload
> 
> Move it to the cpu subsys directory instead of it being per-cpu.
> 
> Cc: Henrique de Moraes Holschuh <hmh@xxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Signed-off-by: Borislav Petkov <borislav.petkov@xxxxxxx>
> ---
>  arch/x86/kernel/microcode_core.c | 32 ++++++++++++++++++++++++++++----
>  1 file changed, 28 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/kernel/microcode_core.c
> b/arch/x86/kernel/microcode_core.c
> index 24b852b61be3..4c6f3b37ed3c 100644
> --- a/arch/x86/kernel/microcode_core.c
> +++ b/arch/x86/kernel/microcode_core.c
> @@ -351,7 +351,6 @@ static DEVICE_ATTR(version, 0400, version_show,
> NULL);
>  static DEVICE_ATTR(processor_flags, 0400, pf_show, NULL);
> 
>  static struct attribute *mc_default_attrs[] = {
> -	&dev_attr_reload.attr,
>  	&dev_attr_version.attr,
>  	&dev_attr_processor_flags.attr,
>  	NULL
> @@ -528,6 +527,16 @@ static const struct x86_cpu_id microcode_id[] = {
>  MODULE_DEVICE_TABLE(x86cpu, microcode_id);
>  #endif
> 
> +static struct attribute *cpu_root_microcode_attrs[] = {
> +	&dev_attr_reload.attr,
> +	NULL
> +};
> +
> +static struct attribute_group cpu_root_microcode_group = {
> +	.name  = "microcode",
> +	.attrs = cpu_root_microcode_attrs,
> +};
> +
>  static int __init microcode_init(void)
>  {
>  	struct cpuinfo_x86 *c = &cpu_data(0);
> @@ -559,9 +568,17 @@ static int __init microcode_init(void)
>  	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;
> +	}
> +
>  	error = microcode_dev_init();
>  	if (error)
> -		goto out_driver;
> +		goto out_ucode_group;
> 
If you put sysfs_create_group() after microcode_dev_init(), out_ucode_group is unnecessary and code is a bit simpler. Microcode_dev_init() doesn't rely on sysfs_create_group() and it's a NULL function any way.

>  	register_syscore_ops(&mc_syscore_ops);
>  	register_hotcpu_notifier(&mc_cpu_notifier);
> @@ -571,7 +588,11 @@ static int __init microcode_init(void)
> 
>  	return 0;
> 
> -out_driver:
> + out_ucode_group:
> +	sysfs_remove_group(&cpu_subsys.dev_root->kobj,
> +			   &cpu_root_microcode_group);
> +
> + out_driver:
>  	get_online_cpus();
>  	mutex_lock(&microcode_mutex);
> 
> @@ -580,7 +601,7 @@ out_driver:
>  	mutex_unlock(&microcode_mutex);
>  	put_online_cpus();
> 
> -out_pdev:
> + out_pdev:
>  	platform_device_unregister(microcode_pdev);
>  	return error;	
> 
> @@ -596,6 +617,9 @@ static void __exit microcode_exit(void)
>  	unregister_hotcpu_notifier(&mc_cpu_notifier);
>  	unregister_syscore_ops(&mc_syscore_ops);
> 
> +	sysfs_remove_group(&cpu_subsys.dev_root->kobj,
> +			   &cpu_root_microcode_group);
> +
>  	get_online_cpus();
>  	mutex_lock(&microcode_mutex);
--
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