Re: [PATCH RFC] KVM: inject #UD if instruction emulation fails while vcpu is in cpl==3

[Avi Kivity <avi@redhat.com>]

On 05/06/2010 03:41 PM, Gleb Natapov wrote:
> On Thu, May 06, 2010 at 03:33:12PM +0300, Avi Kivity wrote:
>    
>> On 05/06/2010 03:25 PM, Gleb Natapov wrote:
>>      
>>>        
>>>> We can expect that from a developer or a user subscribed to kvm@.
>>>> But what about some random user running virt-manager?
>>>>
>>>>          
>>> What virt-manager would do about such error?
>>>        
>> Call up abrt.
>>
>>      
> The idea is not to let userspace process running in a VM kill the VM.
>    

Well, log the problem (including registers and instruction code), and 
continue with the #UD.

>>>> True.  But the same problem exists with cpl>0 #UD.  It may be a
>>>> critical driver in userspace (say, video driver).
>>>>
>>>> Also need to think consider nested kernels (which are userspace for
>>>> this purpose).
>>>>          
>>> Ugh, we can check if vcpu is in nested mode.
>>>        
>> And do what?  Inject #UD to the guest?  Or force some vmexit?
>>
>>      
> Does host emulator will ever run on behalf of nested guest? We have
> emulator inside nested guest for this.
>    

If the guest doesn't map the page, it will emulate.  If it does map the 
page, and the host doesn't, the host emulates.

-- 
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