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Virtual Machine and Virtual Memory
- Three address categories:
- (guest) virtual
- (guest) real
- (host) real
- Page tables
- guest: maps (guest) virtual pages to (guest) real
- host (vmm): maps (guest) real to (host) real
- Shadow Page table
- maps: (guest) virtual pages to (host) real
- composition of guest page table and host page table
- used by hardware when guest executes to avoid extra level of
indirection in address translation
- Requires any attempt by guest to access/change its page table
must trap to the vmm host. (update shadow page table)
- hardware translation uses the shadow page table entries.
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