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* KVM MMU: why  write-protect for the pages containing PML4/PDPT/PDT (page directory) of the guest?
@ 2013-06-13  3:28 yongcheng.wu
  2013-06-13 13:15 ` Paolo Bonzini
  0 siblings, 1 reply; 2+ messages in thread
From: yongcheng.wu @ 2013-06-13  3:28 UTC (permalink / raw)
  To: kvm

I have a problem for shadow page table. 
why is write-protect for the pages containing PML4/PDPT/PDT (page directory) of the guest? In other words, need to synchronize the change of the page directory of the guest?

Best Regards

^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: KVM MMU: why  write-protect for the pages containing PML4/PDPT/PDT (page directory) of the guest?
  2013-06-13  3:28 KVM MMU: why write-protect for the pages containing PML4/PDPT/PDT (page directory) of the guest? yongcheng.wu
@ 2013-06-13 13:15 ` Paolo Bonzini
  0 siblings, 0 replies; 2+ messages in thread
From: Paolo Bonzini @ 2013-06-13 13:15 UTC (permalink / raw)
  To: yongcheng.wu; +Cc: kvm

Il 12/06/2013 23:28, yongcheng.wu@i-soft.com.cn ha scritto:
> I have a problem for shadow page table. why is write-protect for the
> pages containing PML4/PDPT/PDT (page directory) of the guest? In
> other words, need to synchronize the change of the page directory of
> the guest?

Shadow page tables are the combination of both the host and guest page
tables into a single translation.  So they need to be updated every time
the host or the guest change the page tables.  Updates for the host page
tables are tracked with MMU notifiers; updates for the guest page tables
are tracked with write protection.

Paolo

^ permalink raw reply	[flat|nested] 2+ messages in thread

end of thread, other threads:[~2013-06-13 13:15 UTC | newest]

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2013-06-13  3:28 KVM MMU: why write-protect for the pages containing PML4/PDPT/PDT (page directory) of the guest? yongcheng.wu
2013-06-13 13:15 ` Paolo Bonzini

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