Re: [PATCH v5 00/14] Nested PAPR API (KVM on PowerVM)

["Nicholas Piggin" <npiggin@gmail.com>]

On Fri Mar 8, 2024 at 9:19 PM AEST, Harsh Prateek Bora wrote:
> 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.
> 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.
>
> Linux Kernel side support is already merged upstream:

This is all looking pretty good to me now. Considering it's quite
self-contained and adding a new feature, I think it's good to
merge.

I would like to have an avocado test for it, but the avocado
framework has a bug that's causing issues with the ppc hv test,
and we might have to move to a new host kernel with the KVM
support merged. I can take a look at that, I think we can add
new tests after soft-freeze.

Thanks,
Nick

> ---
> commit 19d31c5f115754c369c0995df47479c384757f82
> Author: Jordan Niethe <jniethe5@gmail.com>
> Date:   Thu Sep 14 13:05:59 2023 +1000
>
>     KVM: PPC: Add support for nestedv2 guests
> ---
> 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/iamjpn/kvm-powervm-test
>
> A tree with this series is available at:
> https://github.com/planetharsh/qemu/tree/upstream-0305-v5
>
> Thanks to Michael Neuling, Shivaprasad Bhat, Amit Machhiwal, Kautuk
> Consul, Vaibhav Jain and Jordan Niethe.
>
> Changelog:
> v5: addressed review comments from Nick on v4
> v4: https://lore.kernel.org/qemu-devel/20240220083609.748325-1-harshpb@linux.ibm.com/
> v3: https://lore.kernel.org/qemu-devel/20240118052438.1475437-1-harshpb@linux.ibm.com/
> v2: https://lore.kernel.org/qemu-devel/20231012104951.194876-1-harshpb@linux.ibm.com/
> v1: https://lore.kernel.org/qemu-devel/20230906043333.448244-1-harshpb@linux.ibm.com/
>
> Harsh Prateek Bora (14):
>   spapr: nested: register nested-hv api hcalls only for cap-nested-hv
>   spapr: nested: move nested part of spapr_get_pate into spapr_nested.c
>   spapr: nested: Introduce SpaprMachineStateNested to store related
>     info.
>   spapr: nested: keep nested-hv related code restricted to its API.
>   spapr: nested: Document Nested PAPR API
>   spapr: nested: Introduce H_GUEST_[GET|SET]_CAPABILITIES hcalls.
>   spapr: nested: Introduce H_GUEST_[CREATE|DELETE] hcalls.
>   spapr: nested: Introduce H_GUEST_CREATE_VCPU hcall.
>   spapr: nested: Extend nested_ppc_state for nested PAPR API
>   spapr: nested: Initialize the GSB elements lookup table.
>   spapr: nested: Introduce H_GUEST_[GET|SET]_STATE hcalls.
>   spapr: nested: Use correct source for parttbl info for nested PAPR
>     API.
>   spapr: nested: Introduce H_GUEST_RUN_VCPU hcall.
>   spapr: nested: Introduce cap-nested-papr for Nested PAPR API
>
>  docs/devel/nested-papr.txt    |  119 +++
>  include/hw/ppc/spapr.h        |   27 +-
>  include/hw/ppc/spapr_nested.h |  428 ++++++++-
>  target/ppc/cpu.h              |    4 +
>  hw/ppc/ppc.c                  |   10 +
>  hw/ppc/spapr.c                |   35 +-
>  hw/ppc/spapr_caps.c           |   62 ++
>  hw/ppc/spapr_hcall.c          |   24 +-
>  hw/ppc/spapr_nested.c         | 1550 ++++++++++++++++++++++++++++++++-
>  9 files changed, 2204 insertions(+), 55 deletions(-)
>  create mode 100644 docs/devel/nested-papr.txt