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Re: [Xen-devel] INVVPID question.

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] INVVPID question.
From: Gianluca Guida <gianluca.guida@xxxxxxxxxxxxx>
Date: Tue, 28 Apr 2009 13:49:47 +0100
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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@xxxxxxxxxxxxx> 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

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