linux-kernel - Re: [PATCH] x86/smp: Validate APIC ID before parking CPU in INIT

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Message-ID: <faa32c9f-0456-d3e4-e554-e78eb11c6160@amd.com>
Date:   Mon, 4 Sep 2023 13:57:54 +0530
From:   Vasant Hegde <vasant.hegde@....com>
To:     Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org
Cc:     x86@...nel.org, dave.hansen@...ux.intel.com, bp@...en8.de,
        mingo@...hat.com,
        Dheeraj Kumar Srivastava <dheerajkumar.srivastava@....com>
Subject: Re: [PATCH] x86/smp: Validate APIC ID before parking CPU in INIT

Hi Thomas,


On 8/10/2023 4:56 PM, Vasant Hegde wrote:
> Hi,
> 
> 
> On 8/10/2023 12:22 AM, Thomas Gleixner wrote:
>> On Wed, Aug 09 2023 at 20:42, Thomas Gleixner wrote:
>>> On Wed, Jul 19 2023 at 05:13, Vasant Hegde wrote:
>>>> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
>>>> index e1aa2cd7734b..e5ca0689c4dd 100644
>>>> --- a/arch/x86/kernel/smpboot.c
>>>> +++ b/arch/x86/kernel/smpboot.c
>>>> @@ -1360,7 +1360,7 @@ bool smp_park_other_cpus_in_init(void)
>>>>  		if (cpu == this_cpu)
>>>>  			continue;
>>>>  		apicid = apic->cpu_present_to_apicid(cpu);
>>>> -		if (apicid == BAD_APICID)
>>>> +		if (apicid == BAD_APICID || !apic->apic_id_valid(apicid))
>>>>  			continue;
>>>>  		send_init_sequence(apicid);
>>>>  	}
>>
>> I think this papers over the underlying problem that this sends INIT to
>> an APIC which was never booted. The below is curing the root cause.
> 
> I have tested below patch and it fixes the issue. Thanks
> 
> Tested-by: Vasant Hegde <vasant.hegde@....com>

Ping.

Will you be posting/picking below patch -OR- Do you want me to resend below patch?

-Vasant

> 
> -Vasant
> 
>>
>> Thanks,
>>
>>         tglx
>> ---
>> --- a/arch/x86/kernel/smpboot.c
>> +++ b/arch/x86/kernel/smpboot.c
>> @@ -1356,7 +1356,7 @@ bool smp_park_other_cpus_in_init(void)
>>  	if (this_cpu)
>>  		return false;
>>  
>> -	for_each_present_cpu(cpu) {
>> +	for_each_cpu_and(cpu, &cpus_booted_once_mask, cpu_present_mask) {
>>  		if (cpu == this_cpu)
>>  			continue;
>>  		apicid = apic->cpu_present_to_apicid(cpu);