linux-kernel - Re: [PATCH 6/7] x86/microcode: Request microcode on the BSP

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Message-ID: <a5518704-2264-07b4-dd13-84f0086dbe08@amd.com>
Date:   Mon, 5 Mar 2018 16:08:08 -0600
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Borislav Petkov <bp@...en8.de>, X86 ML <x86@...nel.org>
Cc:     Arjan Van De Ven <arjan.van.de.ven@...el.com>,
        Ashok Raj <ashok.raj@...el.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 6/7] x86/microcode: Request microcode on the BSP

On 2/28/2018 4:28 AM, Borislav Petkov wrote:
> From: Borislav Petkov <bp@...e.de>
> 
> ... so that any newer version can land in the cache and can later be
> fished out by the application functions. Do that before grabbing the
> hotplug lock.
> 
> Signed-off-by: Borislav Petkov <bp@...e.de>
> ---
>  arch/x86/kernel/cpu/microcode/core.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
> 

Reviewed-by: Tom Lendacky <thomas.lendacky@....com>

> diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
> index fa32cb3dcca5..5dd157d48606 100644
> --- a/arch/x86/kernel/cpu/microcode/core.c
> +++ b/arch/x86/kernel/cpu/microcode/core.c
> @@ -499,15 +499,10 @@ static int check_online_cpus(void)
>  static enum ucode_state reload_for_cpu(int cpu)
>  {
>  	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
> -	enum ucode_state ustate;
>  
>  	if (!uci->valid)
>  		return UCODE_OK;
>  
> -	ustate = microcode_ops->request_microcode_fw(cpu, &microcode_pdev->dev, true);
> -	if (ustate != UCODE_OK)
> -		return ustate;
> -
>  	return apply_microcode_on_target(cpu);
>  }
>  
> @@ -515,11 +510,11 @@ static ssize_t reload_store(struct device *dev,
>  			    struct device_attribute *attr,
>  			    const char *buf, size_t size)
>  {
> +	int cpu, bsp = boot_cpu_data.cpu_index;
>  	enum ucode_state tmp_ret = UCODE_OK;
>  	bool do_callback = false;
>  	unsigned long val;
>  	ssize_t ret = 0;
> -	int cpu;
>  
>  	ret = kstrtoul(buf, 0, &val);
>  	if (ret)
> @@ -528,6 +523,10 @@ static ssize_t reload_store(struct device *dev,
>  	if (val != 1)
>  		return size;
>  
> +	tmp_ret = microcode_ops->request_microcode_fw(bsp, &microcode_pdev->dev, true);
> +	if (tmp_ret != UCODE_OK)
> +		return size;
> +
>  	get_online_cpus();
>  
>  	ret = check_online_cpus();
>