Re: [PATCH 1/5] KVM: vmx: fix ept reserved bits for 1-GByte page

From: Paolo Bonzini
Date: Mon Aug 18 2014 - 07:18:46 EST


Il 18/08/2014 12:52, Xiao Guangrong ha scritto:
>> > EPT misconfig handler in kvm will check which reason lead to EPT
>> > misconfiguration after vmexit. One of the reasons is that an EPT
>> > paging-structure entry is configured with settings reserved for
>> > future functionality. However, the handler can't identify if
>> > paging-structure entry of reserved bits for 1-GByte page are
>> > configured, since PDPTE which point to 1-GByte page will reserve
>> > bits 29:12 instead of bits 7:3 which are reserved for PDPTE that
>> > references an EPT Page Directory. This patch fix it by reserve
>> > bits 29:12 for 1-GByte page.
> That mask is only set in the lowest pte for 4K page, i think it
> is not a problem, no?

It will cause KVM to WARN. The EPT memory type will also be ignored for
gigabyte pages.

Paolo
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