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

Hi QEMU/KVM developers, I am sorry if my email disturbs you. I did an experiment and found the guest physical addresses (GPAs) are not the same as the corresponding host virtual addresses (HVAs). I am curious about why; I think they should be the same. I am very appreciated if you can give some comments and suggestions about 1) why GPAs and HVAs are not the same in the following experiment; 2) are there any better experiments to look into the reasons? Any other comments/suggestions are also very welcome. Thanks! The experiment is like this: in a single vCPU VM, I ran a program allocating and referencing lots of pages (e.g., 100*1024) and didn't let the program terminate. Then, I checked the program's guest virtual addresses (GVAs) and GPAs through parsing its pagemap and maps files located at /proc/pid/pagemap and /proc/pid/maps, respectively. At last, in the host OS, I checked the vCPU's pagemap and maps files to find the program's HVAs and host physical addresses (HPAs); I actually checked the new allocated physical pages in the host OS after the program was executed in the guest OS. With the above experiment, I found GPAs of the program are different from its corresponding HVAs. BTW, Intel EPT and other related Intel virtualization techniques were enabled. Thanks, Harry