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[Xen-devel] [RFC] x86_64 and protection

  • To: xen-devel@xxxxxxxxxxxxxxxxxxx
  • From: Mathieu Ropert <mro@xxxxxxxxxx>
  • Date: Fri, 24 Mar 2006 13:05:44 +0100
  • Delivery-date: Fri, 24 Mar 2006 16:44:19 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>


i'm trying to understand how protection with Xen on x86_64 has kernel and user code run on the same privilege level.

Things i'm wondering:
- As all kernel pages must mapped with USER bit, how do i make sure user process can't access them? Unmap all before switching to user mode? - How Xen makes the difference between a kernel and a user process? I think it use a software flag or something to handle syscall instruction properly (ie: processing hypercall or give control to kernel syscalls management depending on the caller).

Some documentations on this would be great for future attempts to port other OS to Xen.



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