linux-kernel - Re: [PATCH] Fix emergency_restart (sysrq-b) with kvm loaded on Intel hosts

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Message-ID: <48B2B533.9070509@qumranet.com>
Date:	Mon, 25 Aug 2008 16:35:47 +0300
From:	Avi Kivity <avi@...ranet.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
CC:	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org
Subject: Re: [PATCH] Fix emergency_restart (sysrq-b) with kvm loaded on Intel
 hosts

Eric W. Biederman wrote:
> Ingo Molnar <mingo@...e.hu> writes:
>
>   
>> * Avi Kivity <avi@...ranet.com> wrote:
>>
>>     
>>> Enabling Intel VT has the curious side effect whereby the INIT signal 
>>> is blocked.  Rather than comment on the wisdom of this side effect, 
>>> this patch adds an emergency restart reboot notifier, and modifies the 
>>> kvm reboot notifier to disable VT on emergency reboot.
>>>       
>
> Please no notifiers in emergency_restart.
>
> First emergency_restart is not supposed to work reliably it is a best effort tickle
> the hardware thing.
>
> Second and more importantly whenever someone adds a notifier instead of a proper hook
> to one a code path like this it seems like avoiding building a proper interface so
> and I believe keeps us from getting all of the logic and the heuristics right.
>
> Why not just add a disable intel_vt if it is enabled call?
>
>   

We need to do it across all cpus.

However, a reliable (and simpler) fix has emerged: reset via ACPI.  That 
causes a true reset which VT does not block.


-- 
error compiling committee.c: too many arguments to function

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