Messages in this thread | | | Date | Wed, 13 Apr 2022 10:38:26 +0200 | Subject | Re: [RFC PATCH V3 2/4] KVM: X86: Introduce role.glevel for level expanded pagetable | From | Paolo Bonzini <> |
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On 4/12/22 23:31, Sean Christopherson wrote: >> + unsigned glevel:4; > We don't need 4 bits for this. Crossing our fingers that we never had to shadow > a 2-level guest with a 6-level host, we can do: > > unsigned passthrough_delta:2; > > Where the field is ignored if direct=1, '0' for non-passthrough, and 1-3 to handle > shadow_root_level - guest_root_level. Basically the same idea as Paolo's smushing > of direct+passthrough into mapping_level, just dressed up differently.
Basically, your passthrough_delta is level - glevel in Jiangshan's patches. You'll need 3 bits anyway when we remove direct later (that would be passthrough_delta == level).
Regarding the naming:
* If we keep Jiangshan's logic, I don't like the glevel name very much, any of mapping_level, target_level or direct_level would be clearer?
* If we go with yours, I would call the field "passthrough_levels".
Paolo
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