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[Xen-devel] TLB-miss handling in Xen 3.0

  • To: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: "Amitayu Das" <amitayudas@xxxxxxxxx>
  • Date: Thu, 2 Mar 2006 16:27:05 -0500
  • Delivery-date: Thu, 02 Mar 2006 21:27:40 +0000
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  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>


I had few questions about page-table used by guest-OSes. Xen interface 3.0 manual says that

1. Each guest-OS has got a *physical-to-machine* table where as the hypervisor has got a globally readable
*machine-to-physical* table.

My questions are the following:

1. An unmodified linux guest-OS would have *virtual-to-physical* mapping in its page-table. Given the    need of para-virtualization,
   does it have a *virtual-to-machine* mapping as well in addition to the mapping talked about in the interface manual?

2. If there exists such a *virtual-to-machine* mapping for a guest-OS (assuming the anwer to Q1 is "yes"), what happens for TLB miss for a process running inside a guest-OS?
    If the hypervisor is responsible for the update, is it aware of virtual address associated with a process running inside a guest-OS and how   does he do it? If any hardware circuitry is responsible for doing that, is it aware of
    virtual address associated with a process running inside a guest-OS and how does he do it?

3. If the answer to Q1 is "no", then is there anything that I'm missing here? And, in that case, can anyone please tell me how a TLB-miss for a process running inside a guest-OS is handled?

Thanks in advance,

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