linux-kernel - Re: [PATCH v6 1/4] x86/mce: Cleanup bank processing on init

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Date:   Fri, 23 Dec 2022 14:23:05 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Yazen Ghannam <yazen.ghannam@....com>
Cc:     linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org,
        tony.luck@...el.com, x86@...nel.org,
        Smita.KoralahalliChannabasappa@....com,
        Borislav Petkov <bp@...e.de>
Subject: Re: [PATCH v6 1/4] x86/mce: Cleanup bank processing on init

On Tue, Dec 06, 2022 at 11:36:04AM -0600, Yazen Ghannam wrote:
> -static void __mcheck_cpu_init_clear_banks(void)
> +static void __mcheck_cpu_init_prepare_banks(void)
>  {
>  	struct mce_bank *mce_banks = this_cpu_ptr(mce_banks_array);
> +	mce_banks_t all_banks;
> +	u64 msrval;
>  	int i;
>  
> -	for (i = 0; i < this_cpu_read(mce_num_banks); i++) {
> -		struct mce_bank *b = &mce_banks[i];
> -
> -		if (!b->init)
> -			continue;
> -		wrmsrl(mca_msr_reg(i, MCA_CTL), b->ctl);
> -		wrmsrl(mca_msr_reg(i, MCA_STATUS), 0);
> +	/*
> +	 * Log the machine checks left over from the previous reset. Log them
> +	 * only, do not start processing them. That will happen in mcheck_late_init()
> +	 * when all consumers have been registered on the notifier chain.
> +	 */
> +	if (mca_cfg.bootlog) {
> +		bitmap_fill(all_banks, MAX_NR_BANKS);
> +		machine_check_poll(MCP_UC | MCP_QUEUE_LOG, &all_banks);
>  	}

Yeah, just a nit ontop - lemme move all_banks into the if branch so that
it is closer and obvious:

---
diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 5f406d135d32..a90d3eb6fcd8 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1755,7 +1755,6 @@ static void __mcheck_cpu_init_generic(void)
 static void __mcheck_cpu_init_prepare_banks(void)
 {
 	struct mce_bank *mce_banks = this_cpu_ptr(mce_banks_array);
-	mce_banks_t all_banks;
 	u64 msrval;
 	int i;
 
@@ -1765,6 +1764,8 @@ static void __mcheck_cpu_init_prepare_banks(void)
 	 * when all consumers have been registered on the notifier chain.
 	 */
 	if (mca_cfg.bootlog) {
+		mce_banks_t all_banks;
+
 		bitmap_fill(all_banks, MAX_NR_BANKS);
 		machine_check_poll(MCP_UC | MCP_QUEUE_LOG, &all_banks);
 	}

-- 
Regards/Gruss,
    Boris.

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