* INVVPID question.
@ 2009-04-28 12:18 Gianluca Guida
2009-04-28 12:52 ` Keir Fraser
0 siblings, 1 reply; 3+ messages in thread
From: Gianluca Guida @ 2009-04-28 12:18 UTC (permalink / raw)
To: xen-devel@lists.xensource.com
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
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: INVVPID question.
2009-04-28 12:18 INVVPID question Gianluca Guida
@ 2009-04-28 12:52 ` Keir Fraser
2009-04-28 12:49 ` Gianluca Guida
0 siblings, 1 reply; 3+ messages in thread
From: Keir Fraser @ 2009-04-28 12:52 UTC (permalink / raw)
To: Gianluca Guida, xen-devel@lists.xensource.com
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
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: INVVPID question.
2009-04-28 12:52 ` Keir Fraser
@ 2009-04-28 12:49 ` Gianluca Guida
0 siblings, 0 replies; 3+ messages in thread
From: Gianluca Guida @ 2009-04-28 12:49 UTC (permalink / raw)
To: Keir Fraser; +Cc: xen-devel@lists.xensource.com
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
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2009-04-28 12:52 ` Keir Fraser
2009-04-28 12:49 ` Gianluca Guida
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