[RFC PATCH v2 0/6] KVM: PPC: Nested PAPR guests

[Jordan Niethe]

There is existing support for nested guests on powernv hosts however the
hcall interface this uses is not support by other PAPR hosts. A set of
new hcalls will be added to PAPR to facilitate creating and managing
guests by a regular partition in the following way:

  - L1 and L0 negotiate capabilities with
    H_GUEST_{G,S}ET_CAPABILITIES

  - L1 requests the L0 create a L2 with
    H_GUEST_CREATE and receives a handle to use in future hcalls

  - L1 requests the L0 create a L2 vCPU with
    H_GUEST_CREATE_VCPU

  - L1 sets up the L2 using H_GUEST_SET and the
    H_GUEST_VCPU_RUN input buffer

  - L1 requests the L0 runs the L2 vCPU using H_GUEST_VCPU_RUN

  - L2 returns to L1 with an exit reason and L1 reads the
    H_GUEST_VCPU_RUN output buffer populated by the L0

  - L1 handles the exit using H_GET_STATE if necessary

  - L1 reruns L2 vCPU with H_GUEST_VCPU_RUN

  - L1 frees the L2 in the L0 with H_GUEST_DELETE

Further details are available in Documentation/powerpc/kvm-nested.rst.

This series adds KVM support for using this hcall interface as a regular
PAPR partition, i.e. the L1. It does not add support for running as the
L0.

The new hcalls have been implemented in the spapr qemu model for
testing.

This is available at https://github.com/mikey/qemu/tree/kvm-papr

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

A tree with this series is available at
https://github.com/iamjpn/linux/tree/features/kvm-papr

Thanks to Amit Machhiwal, Kautuk Consul, Vaibhav Jain, Michael Neuling,
Shivaprasad Bhat, Harsh Prateek Bora, Paul Mackerras and Nicholas
Piggin. 

Change overview in v2:
  - Rebase on top of kvm ppc prefix instruction support
  - Make documentation an individual patch
  - Move guest state buffer files from arch/powerpc/lib/ to
    arch/powerpc/kvm/
  - Use kunit for testing guest state buffer
  - Fix some build errors
  - Change HEIR element from 4 bytes to 8 bytes

Previous revisions:

  - v1: https://lore.kernel.org/linuxppc-dev/20230508072332.2937883-1-jpn@linux.vnet.ibm.com/

Jordan Niethe (5):
  KVM: PPC: Use getters and setters for vcpu register state
  KVM: PPC: Add fpr getters and setters
  KVM: PPC: Add vr getters and setters
  KVM: PPC: Add helper library for Guest State Buffers
  KVM: PPC: Add support for nested PAPR guests

Michael Neuling (1):
  docs: powerpc: Document nested KVM on POWER

 Documentation/powerpc/index.rst               |   1 +
 Documentation/powerpc/kvm-nested.rst          | 636 +++++++++++
 arch/powerpc/Kconfig.debug                    |  12 +
 arch/powerpc/include/asm/guest-state-buffer.h | 988 ++++++++++++++++++
 arch/powerpc/include/asm/hvcall.h             |  30 +
 arch/powerpc/include/asm/kvm_book3s.h         | 205 +++-
 arch/powerpc/include/asm/kvm_book3s_64.h      |   6 +
 arch/powerpc/include/asm/kvm_booke.h          |  10 +
 arch/powerpc/include/asm/kvm_host.h           |  21 +
 arch/powerpc/include/asm/kvm_ppc.h            |  80 +-
 arch/powerpc/include/asm/plpar_wrappers.h     | 198 ++++
 arch/powerpc/kvm/Makefile                     |   4 +
 arch/powerpc/kvm/book3s.c                     |  38 +-
 arch/powerpc/kvm/book3s_64_mmu_hv.c           |   4 +-
 arch/powerpc/kvm/book3s_64_mmu_radix.c        |   9 +-
 arch/powerpc/kvm/book3s_64_vio.c              |   4 +-
 arch/powerpc/kvm/book3s_hv.c                  | 336 ++++--
 arch/powerpc/kvm/book3s_hv.h                  |  65 ++
 arch/powerpc/kvm/book3s_hv_builtin.c          |  10 +-
 arch/powerpc/kvm/book3s_hv_nested.c           |  38 +-
 arch/powerpc/kvm/book3s_hv_p9_entry.c         |   4 +-
 arch/powerpc/kvm/book3s_hv_papr.c             | 940 +++++++++++++++++
 arch/powerpc/kvm/book3s_hv_ras.c              |   5 +-
 arch/powerpc/kvm/book3s_hv_rm_mmu.c           |   8 +-
 arch/powerpc/kvm/book3s_hv_rm_xics.c          |   4 +-
 arch/powerpc/kvm/book3s_xive.c                |   9 +-
 arch/powerpc/kvm/emulate_loadstore.c          |   6 +-
 arch/powerpc/kvm/guest-state-buffer.c         | 612 +++++++++++
 arch/powerpc/kvm/powerpc.c                    |  76 +-
 arch/powerpc/kvm/test-guest-state-buffer.c    | 321 ++++++
 30 files changed, 4467 insertions(+), 213 deletions(-)
 create mode 100644 Documentation/powerpc/kvm-nested.rst
 create mode 100644 arch/powerpc/include/asm/guest-state-buffer.h
 create mode 100644 arch/powerpc/kvm/book3s_hv_papr.c
 create mode 100644 arch/powerpc/kvm/guest-state-buffer.c
 create mode 100644 arch/powerpc/kvm/test-guest-state-buffer.c

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2.31.1