Re: [Xen-ia64-devel] [PATCH] per vcpu vhpt

[Tristan Gingold <Tristan.Gingold@xxxxxxxx>]

Le Lundi 09 Octobre 2006 09:46, Xu, Anthony a écrit :
> Hi Yamahata,
>
> Sorry for late response.
> This is a great patch,
> 1. This patch should alleviate pain from migration.
> 2. VTI-domain and domU now use the same TR number for VHPT mapping, there
> is one more TC available to use, and that's good.
>
> A very small comment,
> I noticed DomU still use VHPT_ADDR to map VHPT. While in function, for
> instance, __vhpt_flush, it uses __va(vhpt_maddr) to access VHPT,  because
> vhpt is allocated from dom heap, this may cause unnecessary tlb miss. There
> are two natural options here.
> 1. If DomU use __va(vhpt_maddr) to map VHPT, the unnecessary tlb miss can
> be eliminated. 2. in function like __vhpt_flush, use VHPT_ADDR to access
> VHPT.
>
> One more thinking is, seems we plan to expose p2m table to domU, in this
> case, if we use VHPT_ADDR to map VHPT, itc can be "emulated" inside domU,
> when domU want to insert a mapping, it can look up p2m for machine physical
> address, then insert the transferred mapping into VHPT directly.
Hi Anthony,

I do not fully understand the last paragraph.  Are you proposing an 
optimization  or do you think there is a bug ?

Although I have not checked I suppose the p2m table is RO.

Tristan.

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