linux-kernel - Re: Subject: [patch V3 09/30] x86/microcode/intel: Switch to kvmalloc()

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Message-Id: <20230925154333.55668-1-qiuxu.zhuo@intel.com>
Date:   Mon, 25 Sep 2023 23:43:33 +0800
From:   Qiuxu Zhuo <qiuxu.zhuo@...el.com>
To:     tglx@...utronix.de
Cc:     arjan@...ux.intel.com, bp@...en8.de, chang.seok.bae@...el.com,
        linux-kernel@...r.kernel.org, nik.borisov@...e.com, x86@...nel.org,
        qiuxu.zhuo@...el.com
Subject: Re: Subject: [patch V3 09/30] x86/microcode/intel: Switch to kvmalloc()

> ...
> From: Thomas Gleixner <tglx@...utronix.de>
> 
> Microcode blobs are getting larger and might soon reach the kmalloc()
> limit. Switch over kvmalloc().
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> 
> ---
>  arch/x86/kernel/cpu/microcode/intel.c |   50 +++++++++++++++++-----------------
>  1 file changed, 26 insertions(+), 24 deletions(-)
> ---
> --- a/arch/x86/kernel/cpu/microcode/intel.c
> +++ b/arch/x86/kernel/cpu/microcode/intel.c
> ... 
>  static void save_microcode_patch(struct microcode_intel *patch)
>  {
> -	struct microcode_intel *mc;
> +	unsigned int size = get_totalsize(&patch->hdr);
> +	struct microcode_intel *mc = NULL;

No need to initialize the 'mc' to NULL as it's unconditionally
set by the following kmemdup().

>  
> -	mc = kmemdup(patch, get_totalsize(&patch->hdr), GFP_KERNEL);
> +	mc = kvmemdup(patch, size, GFP_KERNEL);
>  	if (mc)
>  		update_ucode_pointer(mc);
> +	else
> +		pr_err("Unable to allocate microcode memory size: %u\n", size);
>  }
>  
> ...