[v5,00/33] KVM: PPC: Book3S HV: Nested HV virtualization

Message

Paul Mackerras Oct. 8, 2018, 5:30 a.m. UTC

This patch series implements nested virtualization in the KVM-HV
module for radix guests on POWER9 systems.  Unlike PR KVM, nested
guests are able to run in supervisor mode, meaning that performance is
much better than with PR KVM, and is very close to the performance of
a non-nested guests for most things.

The way this works is that each nested guest is also a guest of the
real hypervisor, also known as the level 0 or L0 hypervisor, which
runs in the CPU's hypervisor mode.  Its guests are at level 1, and
when a L1 system wants to run a nested guest, it performs hypercalls
to L0 to set up a virtual partition table in its (L1's) memory and to
enter the L2 guest.  The L0 hypervisor maintains a shadow
partition-scoped page table for the L2 guest and demand-faults entries
into it by translating the L1 real addresses in the partition-scoped
page table in L1 memory into L0 real addresses and puts them in the
shadow partition-scoped page table for L2.

Essentially what this is doing is providing L1 with the ability to do
(some) hypervisor functions using paravirtualization; optionally,
TLB invalidations can be done through emulation of the tlbie
instruction rather than a hypercall.

Along the way, this implements a new guest entry/exit path for radix
guests on POWER9 systems which is written almost entirely in C and
does not do any of the inter-thread coordination that the existing
entry/exit path does.  It is only used for radix guests and when
indep_threads_mode=Y (the default).

The limitations of this scheme are:

- Host and all nested hypervisors and their guests must be in radix
  mode.

- Nested hypervisors cannot use indep_threads_mode=N.

- If the host (i.e. the L0 hypervisor) has indep_threads_mode=N then
  only one nested vcpu can be run on any core at any given time; the
  secondary threads will do nothing.

- A nested hypervisor can't use a smaller page size than the base page
  size of the hypervisor(s) above it.

- A nested hypervisor is limited to having at most 1023 guests below
  it, each of which can have at most NR_CPUS virtual CPUs (and the
  virtual CPU ids have to be < NR_CPUS as well).

This patch series is against the kvm tree's next branch.

Changes in this version since version 4:

- Added KVM_PPC_NO_HASH to flags field of struct kvm_ppc_smmu_info rather
  than disabling the KVM_PPC_GET_SMMU_INFO ioctl entirely.

- Make sure the hypercalls for controlling nested guests will fail if
  the guest is in HPT mode.

- Made the KVM_CAP_PPC_MMU_HASH_V3 capability report false in a nested
  hypervisor.

- Fixed a bug causing HPT guests to fail to execute real-mode
  hypercalls correctly.

- Fix crashes seen on VM exit or when switching from HPT to radix,
  due to leftover rmap values.

- Removed enable/disable flag from KVM_ENABLE_CAP on the
  KVM_CAP_PPC_NESTED_HV capability; it always enables.

- Fixed a bug causing memory corruption on nested guest startup,
  and a bug where we were never clearing bits in the cpu_in_guest
  cpumask.

- Simplified some code in kvmhv_run_single_vcpu.

Paul.

 Documentation/virtual/kvm/api.txt                  |   19 +
 arch/powerpc/include/asm/asm-prototypes.h          |   21 +
 arch/powerpc/include/asm/book3s/64/mmu-hash.h      |   12 +
 .../powerpc/include/asm/book3s/64/tlbflush-radix.h |    1 +
 arch/powerpc/include/asm/hvcall.h                  |   41 +
 arch/powerpc/include/asm/kvm_asm.h                 |    4 +-
 arch/powerpc/include/asm/kvm_book3s.h              |   45 +-
 arch/powerpc/include/asm/kvm_book3s_64.h           |  118 +-
 arch/powerpc/include/asm/kvm_book3s_asm.h          |    3 +
 arch/powerpc/include/asm/kvm_booke.h               |    4 +-
 arch/powerpc/include/asm/kvm_host.h                |   16 +-
 arch/powerpc/include/asm/kvm_ppc.h                 |    4 +
 arch/powerpc/include/asm/ppc-opcode.h              |    1 +
 arch/powerpc/include/asm/reg.h                     |    2 +
 arch/powerpc/include/uapi/asm/kvm.h                |    1 +
 arch/powerpc/kernel/asm-offsets.c                  |    5 +-
 arch/powerpc/kernel/cpu_setup_power.S              |    4 +-
 arch/powerpc/kvm/Makefile                          |    3 +-
 arch/powerpc/kvm/book3s.c                          |   43 +-
 arch/powerpc/kvm/book3s_64_mmu_hv.c                |    7 +-
 arch/powerpc/kvm/book3s_64_mmu_radix.c             |  718 ++++++++---
 arch/powerpc/kvm/book3s_emulate.c                  |   13 +-
 arch/powerpc/kvm/book3s_hv.c                       |  852 ++++++++++++-
 arch/powerpc/kvm/book3s_hv_builtin.c               |   92 +-
 arch/powerpc/kvm/book3s_hv_interrupts.S            |   95 +-
 arch/powerpc/kvm/book3s_hv_nested.c                | 1291 ++++++++++++++++++++
 arch/powerpc/kvm/book3s_hv_ras.c                   |   10 +
 arch/powerpc/kvm/book3s_hv_rm_xics.c               |   13 +-
 arch/powerpc/kvm/book3s_hv_rmhandlers.S            |  823 +++++++------
 arch/powerpc/kvm/book3s_hv_tm.c                    |    6 +-
 arch/powerpc/kvm/book3s_hv_tm_builtin.c            |    5 +-
 arch/powerpc/kvm/book3s_pr.c                       |    5 +-
 arch/powerpc/kvm/book3s_xics.c                     |   14 +-
 arch/powerpc/kvm/book3s_xive.c                     |   63 +
 arch/powerpc/kvm/book3s_xive_template.c            |    8 -
 arch/powerpc/kvm/bookehv_interrupts.S              |    8 +-
 arch/powerpc/kvm/emulate_loadstore.c               |    1 -
 arch/powerpc/kvm/powerpc.c                         |   15 +-
 arch/powerpc/kvm/tm.S                              |  250 ++--
 arch/powerpc/kvm/trace_book3s.h                    |    1 -
 arch/powerpc/mm/tlb-radix.c                        |    9 +
 include/uapi/linux/kvm.h                           |    2 +
 tools/perf/arch/powerpc/util/book3s_hv_exits.h     |    1 -
 43 files changed, 3806 insertions(+), 843 deletions(-)