linux-kernel - Re: [PATCH v4 1/3] x86, apic: Don't count the CPU with BP flag from MP table as booting-up CPU

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <52817916.9030104@jp.fujitsu.com>
Date:	Tue, 12 Nov 2013 09:40:54 +0900
From:	HATAYAMA Daisuke <d.hatayama@...fujitsu.com>
To:	Vivek Goyal <vgoyal@...hat.com>
CC:	hpa@...ux.intel.com, ebiederm@...ssion.com,
	kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
	bp@...en8.de, akpm@...ux-foundation.org, fengguang.wu@...el.com,
	jingbai.ma@...com
Subject: Re: [PATCH v4 1/3] x86, apic: Don't count the CPU with BP flag from
 MP table as booting-up CPU

(2013/11/12 1:52), Vivek Goyal wrote:
> On Mon, Nov 11, 2013 at 11:52:30AM +0900, HATAYAMA Daisuke wrote:
>
> [..]
>> Looking at my past investigation, kernel/mpparse.c, mm/amdtopology.c and
>> platform/visws/visws_quirks.c assumes that boot_cpu_physical_apicid
>> has initial apicid of the BSP, not the current actual booting-up cpu.
>>
>> These three are called in get_smp_config() below. If either of them is
>> called actually, boot_cpu_physical_apicid has the apicid different from
>> the current actual booting-up cpu temporarily. But init_apic_mappings()
>> soon modifies back the value to the one obtained by read_apic_id().
>>
>>          /*
>>           * Read APIC and some other early information from ACPI tables.
>>           */
>>          acpi_boot_init();
>>          sfi_init();
>>          x86_dtb_init();
>>
>>          /*
>>           * get boot-time SMP configuration:
>>           */
>>          if (smp_found_config)
>>                  get_smp_config();
>>
>>          prefill_possible_map();
>>
>>          init_cpu_to_node();
>>
>>          init_apic_mappings();
>>
>> So, thanks to init_apic_mappings(), the patch set would work without the
>> first patch... This is a careless point in this patch set.
>>
>
> If init_apic_mappings(), is making sure that boot_cpu_physical_apicid is
> apic id of booting processor, and you don't need first patch of your
> series, then I think atleast re-post your patch series without first
> patch.
>

Yes, I'll repost soon.

> And then there can be another series which looks into whether we need
> two different variables or not and if we do, then a separate variable
> bsp_physical_apicid will track the bsp id as reported by BIOS and
> boot_cpu_physical_apicid will track apic id of booting cpu. This might
> a very big and slow cleanup. So I think blocking the first patch series
> behind it might not make much sense.
>

Yes, the current handling of boot_cpu_physical_apicid looks strange and
should be cleaned up, but the cleaning up needs reviewing together with
the maintainers for the corresponding part; in particular, it can be
lengthy for the reviewing on amdtopology.c. I leave this as another
work for the time being.

-- 
Thanks.
HATAYAMA, Daisuke

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/