On 10/08/21 09:40, Yu Zhang wrote:
About "host can't easily mirror L1's desired paging mode", could you please elaborate? Thanks!
Shadow pgae tables in KVM will always have 3 levels on 32-bit machines and 4/5 levels on 64-bit machines. L1 instead might have any number of levels from 2 to 5 (though of course not more than the host has).
Therefore, when shadowing 32-bit NPT page tables, KVM has to add extra fixed levels on top of those that it's shadowing. See mmu_alloc_direct_roots for the code.
Paolo
