linux-kernel - Re: [patch v3 1/7] x86/smp: Make stop_other

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Date:   Fri, 16 Jun 2023 09:53:25 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Ashok Raj <ashok.raj@...el.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Mario Limonciello <mario.limonciello@....com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Tony Battersby <tonyb@...ernetics.com>,
        Ashok Raj <ashok.raj@...ux.intel.com>,
        Tony Luck <tony.luck@...el.com>,
        Arjan van de Veen <arjan@...ux.intel.com>,
        Eric Biederman <ebiederm@...ssion.com>,
        Ashok Raj <ashok.raj@...el.com>
Subject: Re: [patch v3 1/7] x86/smp: Make stop_other_cpus() more robust

On Thu, Jun 15 2023 at 18:58, Ashok Raj wrote:
> On Thu, Jun 15, 2023 at 10:33:50PM +0200, Thomas Gleixner wrote:
>> +			dm = apic->dest_mode_logical ? APIC_DEST_LOGICAL : APIC_DEST_PHYSICAL;
>> +			dm |= APIC_DM_NMI;
>> +
>> +			for_each_cpu(cpu, &cpus_stop_mask) {
>> +				u32 apicid = apic->cpu_present_to_apicid(cpu);
>> +
>> +				apic_icr_write(dm, apicid);
>> +				apic_wait_icr_idle();
>
> can we simplify this by just apic->send_IPI(cpu, NMI_VECTOR); ??

That would not set APIC_DM_NMI in delivery mode and the IPI would be
sent with APIC_DM_FIXED.

Unfortunately we don't have apic->send_NMI() ...

Thanks,

        tglx