[PATCH 00/12] KVM: PPC: Nested APIv2 : Performance improvements

Vaibhav Jain vaibhav at linux.ibm.com
Sat Dec 2 00:26:05 AEDT 2023

From: vaibhav <vajain21 at vajain21.in.ibm.com>

This patch series introduces series of performance improvements to recently
added support for Nested APIv2 PPC64 Guests via [1]. Details for Nested
APIv2 for PPC64 Guests is available in Documentation/powerpc/kvm-nested.rst.

This patch series introduces various optimizations for a Nested APIv2
guests namely:

* Reduce the number times L1 hypervisor requests for L2 state from L0.
* Register the L2 VPA with L1
* Optimizing interrupt delivery of some interrupt types.
* Optimize emulation of mmio loads/stores for L2 in L1.

The hcalls needed for testing these patches have been implemented in the
spapr qemu model and is available at [2].

There are scripts available to assist in setting up an environment for
testing nested guests at [3].

These patches are consequence of insights from on going performance
engineering effort for improving performance of Nested APIv2
Guests. Special thanks goes to:
* Gautam Menghani
* Jordan Niethe
* Nicholas Piggin
* Vaidyanathan Srinivasan

[1] https://lore.kernel.org/all/20230905034658.82835-1-jniethe5@gmail.com
[2] https://github.com/planetharsh/qemu/tree/upstream-0714-kop
[3] https://github.com/iamjpn/kvm-powervm-test

Jordan Niethe (11):
  KVM: PPC: Book3S HV nestedv2: Invalidate RPT before deleting a guest
  KVM: PPC: Book3S HV nestedv2: Avoid reloading the tb offset
  KVM: PPC: Book3S HV nestedv2: Do not check msr on hcalls
  KVM: PPC: Book3S HV nestedv2: Get the PID only if needed to copy
    tofrom a guest
  KVM: PPC: Book3S HV nestedv2: Ensure LPCR_MER bit is passed to the L0
  KVM: PPC: Book3S HV nestedv2: Do not inject certain interrupts
  KVM: PPC: Book3S HV nestedv2: Avoid msr check in
  KVM: PPC: Book3S HV nestedv2: Do not call H_COPY_TOFROM_GUEST
  KVM: PPC: Book3S HV nestedv2: Register the VPA with the L0
  KVM: PPC: Reduce reliance on analyse_instr() in mmio emulation
  KVM: PPC: Book3S HV nestedv2: Do not cancel pending decrementer

Nicholas Piggin (1):
  KVM: PPC: Book3S HV: Handle pending exceptions on guest entry with

 arch/powerpc/include/asm/kvm_book3s.h    | 10 +++-
 arch/powerpc/include/asm/kvm_book3s_64.h |  1 +
 arch/powerpc/kvm/book3s.c                |  4 +-
 arch/powerpc/kvm/book3s_64_mmu_radix.c   |  7 ++-
 arch/powerpc/kvm/book3s_hv.c             | 72 +++++++++++++++++-------
 arch/powerpc/kvm/book3s_hv_nested.c      |  2 +-
 arch/powerpc/kvm/book3s_hv_nestedv2.c    | 29 ++++++++++
 arch/powerpc/kvm/emulate_loadstore.c     | 21 ++++---
 8 files changed, 107 insertions(+), 39 deletions(-)


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