linux-kernel - Re: [Help Test] kdump, x86, acpi: Reproduce CPU0 SMI corruption issue after unsetting BSP flag

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]

Date:	Mon, 19 Aug 2013 11:29:47 +0900
From:	HATAYAMA Daisuke <d.hatayama@...fujitsu.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
CC:	Jingbai Ma <jingbai.ma@...com>, Fenghua Yu <fenghua.yu@...el.com>,
	"kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"Mitchell, Lisa (MCLinux in Fort Collins)" <lisa.mitchell@...com>,
	"H. Peter Anvin" <hpa@...or.com>, bhelgaas@...gle.com,
	Vivek Goyal <vgoyal@...hat.com>
Subject: Re: [Help Test] kdump, x86, acpi: Reproduce CPU0 SMI corruption issue
 after unsetting BSP flag

(2013/08/15 4:45), Eric W. Biederman wrote:
> Jingbai Ma <jingbai.ma@...com> writes:
>
>> I found a side effect of unsetting BSP flag.
>> It affected system rebooting, once the BSP flags been removed, and issue
>> reboot command, system will hang after message:
>> Restarting system.
>> And have to do a hardware reset to recover it.
>>
>> I have reproduced this problem on the following systems:
>> HP EliteBook 6930p
>> HP Compaq DC7700
>> HP ProLiant DL980 (4 sockets, 40 cores)
>>
>> I have an idea: To avoid such kind of issue, we can unset BSP flag in
>> the first kernel during crash processing, and restore it in the second
>> kernel in the APs initializing.
>
> The premise was clearing BSP would not be an issue.  If we could
> reliably count on unsetting the BSP during crash processing we could
> just switch to the BSP and be done totally avoid this problem.
>
> Given that there are reald world issues with clearing the BSP flag,
> I believe the alternate suggestion was to simply never attempt to start
> the bootstrap processor during processor bring up.
>
> If as normal we are running on the bootstrap processor everything will
> work the same, but if we are in the kdump scenario we will be short one
> core.  Being short one core seems like a reasonable tradeoff between
> reliability and performance.
>
> Eric

Sorry Eric, I'm not clear to what you mean by ``short one core''...
Which are you suggesting? Disabling BSP if crash happens on AP is reasonable?
Or restricting cpus to a single one only just as the current kdump
configuration is reasonable?

-- 
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/