INVVPID question.

INVVPID question.

[Gianluca Guida]

Hello,

I have a simple question for the Intel EPT/VPID experts: do current 
implementation of invvpid flushes also VPID 0 when 2 is the first 
argument (as in vpid_sync_all() in Xen)?

Thanks in advance,
Gianluca

Re: INVVPID question.

[Gianluca Guida]

Keir Fraser wrote:
> The instruction reference manual explicitly states that it is not guaranteed
> to flush VPID 0 (but also says that it 'might'). Can't be relied on.

Yes, this is why I was asking about current implementation.

I've been recently playing with shadows and separate (guest/host) tlb 
flushing, and from what I've understood this is what is going on.
Since we use it in vmx_flush_guest_tlbs(), we could perhaps find a way, 
in case tlb flushing optimizations are important to fix this (e.g. using 
vpid_sync_vcpu_all() when current is defined and we're sure there are no 
other vpid-tagged entries in the processor tlb).

Gianluca


> 
>  -- Keir
> 
> On 28/04/2009 13:18, "Gianluca Guida" <gianluca.guida@eu.citrix.com> wrote:
> 
>> Hello,
>>
>> I have a simple question for the Intel EPT/VPID experts: do current
>> implementation of invvpid flushes also VPID 0 when 2 is the first
>> argument (as in vpid_sync_all() in Xen)?
>>
>> Thanks in advance,
>> Gianluca
>>
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@lists.xensource.com
>> http://lists.xensource.com/xen-devel
> 
> 

Re: INVVPID question.

[Keir Fraser]

The instruction reference manual explicitly states that it is not guaranteed
to flush VPID 0 (but also says that it 'might'). Can't be relied on.

 -- Keir

On 28/04/2009 13:18, "Gianluca Guida" <gianluca.guida@eu.citrix.com> wrote:

> Hello,
> 
> I have a simple question for the Intel EPT/VPID experts: do current
> implementation of invvpid flushes also VPID 0 when 2 is the first
> argument (as in vpid_sync_all() in Xen)?
> 
> Thanks in advance,
> Gianluca
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel