On Mon, Apr 26, 2021, Maxim Levitsky wrote:

This patch set aims to fix few flaws that were discovered
in KVM_{GET|SET}_SREGS on x86:

* There is no support for reading/writing PDPTRs although
  these are considered to be part of the guest state.

* There is useless interrupt bitmap which isn't needed

* No support for future extensions (via flags and such)

Also if the user doesn't use the new SREG2 api, the PDPTR
load after migration is now done on KVM_REQ_GET_NESTED_STATE_PAGES
to at least read them correctly in cases when guest memory
map is not up to date when nested state is loaded.

This patch series was tested by doing nested migration test
of 32 bit PAE L1 + 32 bit PAE L2 on AMD and Intel and by
nested migration test of 64 bit L1 + 32 bit PAE L2 on AMD.
The later test currently fails on Intel (regardless of my patches).

Changes from V1:
  - move only PDPTRS load to KVM_REQ_GET_NESTED_STATE_PAGES on VMX
  - rebase on top of kvm/queue
  - improve the KVM_GET_SREGS2 to have flag for PDPTRS
    and remove padding

Patches to qemu will be send soon as well.

How did you want to handle integration with the removal of pdptrs_changed()?

https://lkml.kernel.org/r/68ff1249-2902-43d5-3dfd-35b1f14c4f90@redhat.com