On 28/11/16 08:44, 唐伟文 wrote: > Hi, > > I have a question that why dose xen hypervisor set entry of ept as > invalid (misconfigured) deliberately which will cause VM exit > resulting from EPT > Misconfigurations. > http://xenbits.xenproject.org/gitweb/?p=xen.git;a=commit;h=aa9114edd97b292cd89b3616e3f2089471fd2201 > I > find the answer in this website which is about a patch of xen. They > say that it is necessary to set EPT entry as misconfigured in order to > force re-evaluation of memory type as necessary. > > But, I still don't konw why we need to reevaluate memory type? That is > to say, why can't we determine memory type during the initialization > of EPT. And if it is necessary to do this , which entry of EPT should > be misconfigured intentionally? Thanks
EPT Memory types change at runtime, due to guest actions such as changing the MTRRs, changing CR0.CD, etc, or due to toolstack options such as enabling logdirty mode for live migration. ~Andrew
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