linux-kernel - Re: [PATCH v6 08/11] x86/smpboot: Send INIT/SIPI/SIPI to secondary CPUs in parallel

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Date:   Tue, 07 Feb 2023 01:28:25 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Usama Arif <usama.arif@...edance.com>, dwmw2@...radead.org,
        arjan@...ux.intel.com
Cc:     mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        hpa@...or.com, x86@...nel.org, pbonzini@...hat.com,
        paulmck@...nel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, rcu@...r.kernel.org, mimoja@...oja.de,
        hewenliang4@...wei.com, thomas.lendacky@....com, seanjc@...gle.com,
        pmenzel@...gen.mpg.de, fam.zheng@...edance.com,
        punit.agrawal@...edance.com, simon.evans@...edance.com,
        liangma@...ngbit.com, David Woodhouse <dwmw@...zon.co.uk>,
        Usama Arif <usama.arif@...edance.com>
Subject: Re: [PATCH v6 08/11] x86/smpboot: Send INIT/SIPI/SIPI to secondary
 CPUs in parallel

On Thu, Feb 02 2023 at 21:56, Usama Arif wrote:

> From: David Woodhouse <dwmw@...zon.co.uk>
>
> When the APs can find their own APIC ID without assistance, we can do

We can do nothing ... Again, read Documentation/process ...

> the AP bringup in parallel.
>  /**
>   * arch_disable_smp_support() - disables SMP support for x86 at runtime
>   */
> @@ -1550,6 +1560,10 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
>  		do_parallel_bringup = false;
>  	}
>  
> +	if (do_parallel_bringup)
> +		cpuhp_setup_state_nocalls(CPUHP_BP_PARALLEL_DYN, "x86/cpu:kick",
> +					  native_cpu_kick, NULL);

https://www.kernel.org/doc/html/latest/process/maintainer-tip.html#bracket-rules

Thanks,

        tglx