Re: [PATCH] QEMU-KVM: MCE: Relay UCR MCE to guest

[Avi Kivity <avi@redhat.com>]

On 09/08/2009 11:11 AM, Andi Kleen wrote:
>
>> Does this potentially open a security hole for us?  Consider the following:
>>
>> 1) We happen to read guest memory and that causes an MCE.  For instance,
>> say we're in virtio.c and we read the virtio ring.
>> 2) That should trigger the kernel to generate a sigbus.
>> 3) We catch sigbus, and queue an MCE for delivery.
>> 4) After sigbus handler completes, we're back in virtio.c, what was the
>> value of the memory operation we just completed?
>>      
> Yes for any errors on accessing qemu internal memory that is not
> owned by the guest image you should abort. I thought Ying's patch
> did that already though, by aborting if there's no slot match.
>    

User-mode qemu access should abort even if accessing guest memory, since 
there no way to recover the thread of execution (need a kernel-style 
exception table for each instruction that accesses guest memory, which 
would be a total overkill).

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