There is an existing Nested-HV API to enable nested guests on powernv
machines. However, that is not supported on pseries/PowerVM LPARs.
This patch series implements required hcall interfaces to enable nested
guests with KVM on PowerVM.
Unlike Nested-HV, with this API, entire L2 state is retained by L0
during guest entry/exit and uses pre-defined Guest State Buffer (GSB)
format to communicate guest state between L1 and L2 via L0.

L0 here refers to the phyp/PowerVM, or launching a Qemu TCG L0 with the
newly introduced option cap-nested-papr=true (refer patch 5/15).
L1 refers to the LPAR host on PowerVM or Linux booted on Qemu TCG with
above mentioned option cap-nested-papr=true.
L2 refers to nested guest running on top of L1 using KVM.
No SW changes needed for Qemu running in L1 Linux as well as L2 Kernel.

There is a Linux Kernel side patch series to enable support for Nested
PAPR in L1 and same can be found at below url:

Linux Kernel RFC PATCH v2:
- https://lore.kernel.org/linuxppc-dev/20230605064848.12319-1-jpn@linux.vnet.ibm.com/

For more details, documentation can be referred in either of patch series.

There are scripts available to assist in setting up an environment for
testing nested guests at https://github.com/mikey/kvm-powervm-test

Thanks to Michael Neuling, Shivaprasad Bhat, Kautuk Consul, Vaibhav Jain
and Jordan Niethe.

Harsh Prateek Bora (15):
  ppc: spapr: Introduce Nested PAPR API related macros
  ppc: spapr: Add new/extend structs to support Nested PAPR API
  ppc: spapr: Use SpaprMachineStateNested's ptcr instead of nested_ptcr
  ppc: spapr: Start using nested.api for nested kvm-hv api
  ppc: spapr: Introduce cap-nested-papr for nested PAPR API
  ppc: spapr: Implement nested PAPR hcall - H_GUEST_GET_CAPABILITIES
  ppc: spapr: Implement nested PAPR hcall - H_GUEST_SET_CAPABILITIES
  ppc: spapr: Implement nested PAPR hcall - H_GUEST_CREATE
  ppc: spapr: Implement nested PAPR hcall - H_GUEST_CREATE_VCPU
  ppc: spapr: Initialize the GSB Elements lookup table.
  ppc: spapr: Implement nested PAPR hcall - H_GUEST_[GET|SET]_STATE
  ppc: spapr: Use correct source for parttbl info for nested PAPR API.
  ppc: spapr: Implement nested PAPR hcall - H_GUEST_RUN_VCPU
  ppc: spapr: Implement nested PAPR hcall - H_GUEST_DELETE
  ppc: spapr: Document Nested PAPR API

 docs/devel/nested-papr.txt      |  500 ++++++++++
 hw/ppc/spapr.c                  |   28 +-
 hw/ppc/spapr_caps.c             |   50 +
 hw/ppc/spapr_hcall.c            |    1 +
 hw/ppc/spapr_nested.c           | 1504 +++++++++++++++++++++++++++++--
 include/hw/ppc/ppc.h            |    2 +
 include/hw/ppc/spapr.h          |   35 +-
 include/hw/ppc/spapr_cpu_core.h |    7 +-
 include/hw/ppc/spapr_nested.h   |  378 ++++++++
 target/ppc/cpu.h                |    2 +
 10 files changed, 2433 insertions(+), 74 deletions(-)
 create mode 100644 docs/devel/nested-papr.txt

-- 
2.39.3