linux-kernel - Re: [PATCH] x86/mce: Schedule mce_setup() on correct CPU for CPER decoding

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Date:   Thu, 15 Jun 2023 17:20:31 +0200
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
Subject: Re: [PATCH] x86/mce: Schedule mce_setup() on correct CPU for CPER
 decoding

On Mon, Apr 17, 2023 at 04:20:06PM +0000, Yazen Ghannam wrote:
> @@ -97,20 +102,13 @@ int apei_smca_report_x86_error(struct cper_ia_proc_ctx *ctx_info, u64 lapic_id)
>  	if (ctx_info->reg_arr_size < 48)
>  		return -EINVAL;
>  
> -	mce_setup(&m);
> -
> -	m.extcpu = -1;
> -	m.socketid = -1;
> -
> -	for_each_possible_cpu(cpu) {
> -		if (cpu_data(cpu).initial_apicid == lapic_id) {
> -			m.extcpu = cpu;
> -			m.socketid = cpu_data(m.extcpu).phys_proc_id;
> +	for_each_possible_cpu(cpu)
> +		if (cpu_data(cpu).initial_apicid == lapic_id)
>  			break;
> -		}
> -	}
>  
> -	m.apicid = lapic_id;
> +	if (smp_call_function_single(cpu, __mce_setup, &m, 1))

I can see the following call-chain from NMI context which is a no-no:

ghes_notify_nmi
|-> ghes_in_nmi_spool_from_list
    |-> ghes_in_nmi_queue_one_entry
        |-> __ghes_panic
	    |-> __ghes_print_estatus
	        |-> cper_estatus_print
		    |-> cper_estatus_print_section
		        |-> cper_print_proc_ia
			    |-> arch_apei_report_x86_error
			        |-> apei_smca_report_x86_error
				    |-> smp_call_function_single


-- 
Regards/Gruss,
    Boris.

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