Why guest physical addresses are not the same as the corresponding host virtual addresses in QEMU/KVM? Thanks!

Paolo Bonzini pbonzini at redhat.com
Wed Oct 14 08:28:05 UTC 2020


On 14/10/20 00:40, harry harry wrote:
> Q1: Is there any file like ``/proc/pid/pagemap'' to record the
> mappings between GPAs and HVAs in the host OS?

No, there isn't.

> Q2: Seems that there might be extra overhead (e.g., synchronization
> between EPT tables and host regular page tables; maintaining extra
> regular page tables and data structures), which is caused by the extra
> translation between GPAs to HVAs via memslots. Why doesn't KVM
> directly use GPAs as HVAs and leverage extended/nested page tables to
> translate HVAs (i.e., GPAs) to HPAs?

See my other answer.  What you are saying is simply not possible.

Paolo




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