Re: [Xen-devel] [PATCH][VT] Patch to allow VMX domainsto be destroyedor shut down cleanly

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 19 Sep 2005, at 06:54, Jiang, Yunhong wrote:

> More exactly should be:
>         if (!vmx_paging_enabled(d)) {
>                         get_page for new mfn
>                         put_page for old mfn
>         }
What would old_mfn be in this case?

If we do any cr3 ref-counting on cr0 writes I would expect it to be:
 * put_page() on clearing of CR0_PG
 * get_page() on setting of CR0_PG

Given that writing cr3 currently does a get_page/put_page regardless of 
the setting of CR0_PG, is there any need to be doing get_page() within 
vmx_set_cr0()?
I think it's more correct to do get/put in vmx_set_cr0 (at that point 
we can know what format the pagetables should be, for example 
(32/32p/64). But I think it's a bigger cleanup patch.
Whatever you go for: please send a complete tested patch. :-)

 -- Keir


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