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[Xen-devel] RE: EPT walks for guest page table

Even if the guest wants to read data or execute code, the guest page table may need to be modified for the processor to set the A bit when running with paging enabled. This means NPT or EPT needs to set the W permission for the guest page table pages to avoid VM exits or EPT violation. Depending on the implementation, the A bit may need to be set upfront even if the translation turns to be invalid.



Intel Open Source Technology Center

From: bo ma [mailto:kyle.ma83@xxxxxxxxx]
Sent: Monday, November 24, 2008 1:37 AM
To: xen-devel@xxxxxxxxxxxxxxxxxxx
Cc: Nakajima, Jun; Xin, Xiaohui
Subject: EPT walks for guest page table



I am really confused about  NPT walks for guest page table , and  eager to know the details about it.
It is  treated as data writes even if the access itself is a code read in AMD NPT.I just want to know : is it the same in EPT?

Could anyone help me? I would like to know that very much

Thank you in advance


Bo Ma

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