Re: [Xen-devel] Question about monitor_table

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 14 Feb 2006, at 14:03, Travis Johnson wrote:

> Could someone help me understand the need for the monitor page table. I
> figure that arch_vcpu->guest_table points to a guests L2 page table 
> (PD on x86) and arch_vcpu->shadow_table points to the guest_table's 
> shadow table (if shadowing is turned on) but I don't quite get the 
> purpose of the monitor_table. On x86_32 it seems like it just gets set 
> to the value of the guest table on initialization and I lose track of 
> it after that. I understand Xen needs to trap page table updates but I 
> figured that would be a privileged operation and Xen could trap those 
> accesses through hardware faults or by paravirtualizing through 
> hypercalls (do_mmu_update).
> That's a large amount of figuring so if someone could shed some light 
> on the purpose and use of the monitor table I would appreciate it.
When running a fully-virtualised (HVM) guest, monitor_table is the 
pagetable that is used while Xen runs.
-- Keir


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