linux-kernel - Re: [PATCH 6/13] KVM: memory slot management

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Message-ID: <45446FF8.50502@qumranet.com>
Date:	Sun, 29 Oct 2006 11:10:16 +0200
From:	Avi Kivity <avi@...ranet.com>
To:	Arnd Bergmann <arnd@...db.de>
CC:	linux-kernel@...r.kernel.org, kvm-devel@...ts.sourceforge.net
Subject: Re: [PATCH 6/13] KVM: memory slot management

Arnd Bergmann wrote:
>> It can shoot not only its foot, but anything the monitor's uid has 
>> access to.  Host files, the host network, other guests belonging to the 
>> user, etc.
>>     
>
> Yes, that's what I meant. It's obviously nicer if the guest can't do that,
> but it's a tradeoff of the potential security impact against on how hard
> it is to implement hiding the addresses you don't want your guest to see.
> To put it into other words, do you want the optimal performance, or the
> optimal security?
>
>   

Well, isolation is one of the most significant features of full 
virtualization, both for security and reliability.  I don't think we can 
compromise that.


>> It's worse than I thouht: tlb entries generated by guest accesses are 
>> tagged with the guest virtual address, to if you remove a guest 
>> physical/host virtual page you need to invalidate the entire guest tlb.
>>     
>
> Ok, so it's the HW's fault. They either copied bad or decided doing the
> s390 approach was too expensive.
>   

x86 tradition is to make all possible mistakes before getting a working 
solution.

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

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