linux-kernel - Re: [PATCH] x86: kvm: reset the bootstrap processor when it gets an INIT

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Date:	Mon, 11 Mar 2013 20:01:30 +0100
From:	Jan Kiszka <jan.kiszka@...mens.com>
To:	Gleb Natapov <gleb@...hat.com>
CC:	Paolo Bonzini <pbonzini@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"mtosatti@...hat.com" <mtosatti@...hat.com>
Subject: Re: [PATCH] x86: kvm: reset the bootstrap processor when it gets
 an INIT

On 2013-03-11 19:51, Gleb Natapov wrote:
>>> On Intel:
>>> CPU 1                          CPU 2 in a guest mode
>>> send INIT
>>> send SIPI
>>>                                 INIT vmexit
>>>                                 vmxoff
>>>                                 reset and start from SIPI vector
>>
>> Is SIPI sticky as well, even if the CPU is not in the wait-for-SIPI
>> state (but runnable and in vmxon) while receiving it?
>>
> That what they seams to be saying:
>  However, an INIT and SIPI interrupts sent to a CPU during time when
>  it is in a VMX mode are remembered and delivered, perhaps hours later,
>  when the CPU exits the VMX mode
> 
> Otherwise their exploit will not work.

Very weird, specifically as SIPI is not just a binary event but carries
payload. Will another SIPI event overwrite the previously "saved"
vector? We are deep into an underspecified area...

Jan

-- 
Siemens AG, Corporate Technology, CT RTC ITP SDP-DE
Corporate Competence Center Embedded Linux
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