Nested paging and Shadow paging are examples of hardware techniques used to virtualize memory

Nested paging and Shadow paging are examples of hardware techniques used to virtualize memory.
Nested paging is used more frequently than Shadow paging. It has two hardware page-table tips in the processor to perform namely guest virtual address and host virtual address. In the best case, the virtualized address translation directly translates from guest virtual address and host virtual address with no cost. In the worst case, it perform a nested page walk that multiplies costs. Note that additional hardware is required for nested page walk on the far side the bottom native page walk. It shows how page table memory references grow from a native four to a virtualized twenty-four references. Although page-walk caches will accept a number of these references, TLB misses stay considerably more expensive with virtualization. Nested paging allows fast, direct updates to each page tables without any VMM intervention.

There are two hardware page-table tips in the processor to perform a complete translation which are guest virtual address and host virtual address in nested paging. In the best case, the virtualized address translation options a success at intervals in the TLB to directly translate from guest virtual address and host virtual address with no cost. A TLB miss must perform a nested page walk that multiplies overheads in the worst case. Note that additional hardware is required for nested page walk on the far side the bottom native page walk. It shows how page table memory references grow from a native four to a virtualized twenty-four references.Although page-walk caches will accept a number of these references, TLB misses stay considerably more expensive with virtualization. Nested paging allows rapid and direct updates to each table without any host virtual monitor intervention regardless of the costs.

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Shadow paging is less used to virtualize hardware memory. The VMM in shadow paging creates a shadow page table that holds complete translations from guest virtual address and host virtual address by combining entries from the guest and host tables. In the best case the address translation directly translates from guest virtual address and host virtual address.
Extra hardware support for page walks as a software package is not required. TLB method costs less than the native execution does, it also doesn’t permit direct updates to the page tables. This is due to shadow page table having to be kept consistent with guest and host page tables. Every page table update needs an expensive host virtual monitor intervention to fix the shadow page table by unsupportive or change its entries, that causes significant overheads in several applications.