[PATCH v4 00/17] perf: KVM: Fix, optimize, and clean up callbacks

[Sean Christopherson]

This is a combination of ~2 series to fix bugs in the perf+KVM callbacks,
optimize the callbacks by employing static_call, and do a variety of
cleanup in both perf and KVM.

For the non-perf patches, I think everything except patch 13 (Paolo) and
patches 15 and 16 (Marc) has the appropriate acks.

Patch 1 fixes a set of mostly-theoretical bugs by protecting the guest
callbacks pointer with RCU.

Patches 2 and 3 fix an Intel PT handling bug where KVM incorrectly
eats PT interrupts when PT is supposed to be owned entirely by the host.

Patches 4-9 clean up perf's callback infrastructure and switch to
static_call for arm64 and x86 (the only survivors).

Patches 10-17 clean up related KVM code and unify the arm64/x86 callbacks.

Based on Linus' tree, commit cb690f5238d7 ("Merge tag 'for-5.16/drivers...).

v4:
  - Rebase.
  - Collect acks and reviews.
  - Fully protect perf_guest_cbs with RCU. [Paolo].
  - Add patch to hide arm64's kvm_arm_pmu_available behind
    CONFIG_HW_PERF_EVENTS=y.

v3:
  - https://lore.kernel.org/all/20210922000533.713300-1-seanjc@xxxxxxxxxx/
  - Add wrappers for guest callbacks to that stubs can be provided when
    GUEST_PERF_EVENTS=n.
  - s/HAVE_GUEST_PERF_EVENTS/GUEST_PERF_EVENTS and select it from KVM
    and XEN_PV instead of from top-level arm64/x86. [Paolo]
  - Drop an unnecessary synchronize_rcu() when registering callbacks. [Peter]
  - Retain a WARN_ON_ONCE() when unregistering callbacks if the caller
    didn't provide the correct pointer. [Peter]
  - Rework the static_call patch to move it all to common perf.
  - Add a patch to drop the (un)register stubs, made possible after
    having KVM+XEN_PV select GUEST_PERF_EVENTS.
  - Split dropping guest callback "support" for arm, csky, etc... to a
    separate patch, to make introducing GUEST_PERF_EVENTS cleaner.
  
v2 (relative to static_call v10):
  - Split the patch into the semantic change (multiplexed ->state) and
    introduction of static_call.
  - Don't use '0' for "not a guest RIP".
  - Handle unregister path.
  - Drop changes for architectures that can be culled entirely.

v2 (relative to v1):
  - https://lkml.kernel.org/r/20210828003558.713983-6-seanjc@xxxxxxxxxx
  - Drop per-cpu approach. [Peter]
  - Fix mostly-theoretical reload and use-after-free with READ_ONCE(),
    WRITE_ONCE(), and synchronize_rcu(). [Peter]
  - Avoid new exports like the plague. [Peter]

v1:
  - https://lkml.kernel.org/r/20210827005718.585190-1-seanjc@xxxxxxxxxx

v10 static_call:
  - https://lkml.kernel.org/r/20210806133802.3528-2-lingshan.zhu@xxxxxxxxx

Like Xu (1):
  perf/core: Rework guest callbacks to prepare for static_call support

Sean Christopherson (16):
  perf: Protect perf_guest_cbs with RCU
  KVM: x86: Register perf callbacks after calling vendor's
    hardware_setup()
  KVM: x86: Register Processor Trace interrupt hook iff PT enabled in
    guest
  perf: Stop pretending that perf can handle multiple guest callbacks
  perf: Drop dead and useless guest "support" from arm, csky, nds32 and
    riscv
  perf: Add wrappers for invoking guest callbacks
  perf: Force architectures to opt-in to guest callbacks
  perf/core: Use static_call to optimize perf_guest_info_callbacks
  KVM: x86: Drop current_vcpu for kvm_running_vcpu + kvm_arch_vcpu
    variable
  KVM: x86: More precisely identify NMI from guest when handling PMI
  KVM: Move x86's perf guest info callbacks to generic KVM
  KVM: x86: Move Intel Processor Trace interrupt handler to vmx.c
  KVM: arm64: Convert to the generic perf callbacks
  KVM: arm64: Hide kvm_arm_pmu_available behind CONFIG_HW_PERF_EVENTS=y
  KVM: arm64: Drop perf.c and fold its tiny bits of code into arm.c
  perf: Drop guest callback (un)register stubs

 arch/arm/kernel/perf_callchain.c   | 28 ++------------
 arch/arm64/include/asm/kvm_host.h  | 11 +++++-
 arch/arm64/kernel/image-vars.h     |  2 +
 arch/arm64/kernel/perf_callchain.c | 13 ++++---
 arch/arm64/kvm/Kconfig             |  1 +
 arch/arm64/kvm/Makefile            |  2 +-
 arch/arm64/kvm/arm.c               | 10 ++++-
 arch/arm64/kvm/perf.c              | 59 ------------------------------
 arch/arm64/kvm/pmu-emul.c          |  2 +
 arch/csky/kernel/perf_callchain.c  | 10 -----
 arch/nds32/kernel/perf_event_cpu.c | 29 ++-------------
 arch/riscv/kernel/perf_callchain.c | 10 -----
 arch/x86/events/core.c             | 13 ++++---
 arch/x86/events/intel/core.c       |  5 +--
 arch/x86/include/asm/kvm_host.h    |  7 +++-
 arch/x86/kvm/Kconfig               |  1 +
 arch/x86/kvm/pmu.c                 |  2 +-
 arch/x86/kvm/svm/svm.c             |  2 +-
 arch/x86/kvm/vmx/vmx.c             | 25 ++++++++++++-
 arch/x86/kvm/x86.c                 | 58 +++++------------------------
 arch/x86/kvm/x86.h                 | 17 +++++++--
 arch/x86/xen/Kconfig               |  1 +
 arch/x86/xen/pmu.c                 | 32 +++++++---------
 include/kvm/arm_pmu.h              | 19 ++++++----
 include/linux/kvm_host.h           | 10 +++++
 include/linux/perf_event.h         | 44 ++++++++++++++++------
 init/Kconfig                       |  4 ++
 kernel/events/core.c               | 41 +++++++++++++++------
 virt/kvm/kvm_main.c                | 44 ++++++++++++++++++++++
 29 files changed, 246 insertions(+), 256 deletions(-)
 delete mode 100644 arch/arm64/kvm/perf.c

-- 
2.34.0.rc0.344.g81b53c2807-goog