[PATCH RFC 00/10] KVM: Enable Clang Context Analysis

[Marco Elver <elver@google.com>]

Enable compiler-based static context analysis [1] for x86 KVM, along with
prerequisite lock annotations in virt/kvm.

During the initial annotation pass, context analysis uncovered a missing
SRCU read-side critical section in x86 PMU filter lookups; patch 1 fixes
this bug.

The remainder of the series is strictly non-functional: it establishes
basic function annotations, guarded_by annotations on core structs, and
straightforward refactorings in hva/gfn range walks and guest_memfd to
eliminate conditional locking patterns that cannot be tracked statically.

Annotating the MMU (mmu/mmu.c, mmu/tdp_mmu.c), i8259, and Xen requires
more invasive changes and is deferred to follow-ups.

[1] https://docs.kernel.org/next/dev-tools/context-analysis.html

Marco Elver (10):
  KVM: x86/pmu: Acquire SRCU in pmc_is_event_allowed() to protect filter
    lookup
  KVM: Allow reading memslots while holding slots_arch_lock
  KVM: guest_memfd: Avoid conditional mmu_lock acquisition
  KVM: Refactor kvm_handle_hva_range() to avoid conditional mmu_lock
  KVM: Refactor kvm_handle_gfn_range() to avoid conditional mmu_lock
  KVM: Add basic lock context annotations
  KVM: x86: Add basic lock context annotations
  KVM: Add guarded_by to members in struct kvm
  KVM: x86: Add guarded_by annotations for kvm_arch, kvm_hv, and ioapic
  KVM: x86: Enable CONTEXT_ANALYSIS with opt-outs

 arch/x86/include/asm/kvm_host.h          |  32 ++--
 arch/x86/kvm/Makefile                    |   8 +
 arch/x86/kvm/debugfs.c                   |   1 +
 arch/x86/kvm/hyperv.c                    |  21 +++
 arch/x86/kvm/hyperv.h                    |  16 +-
 arch/x86/kvm/ioapic.c                    |  28 ++-
 arch/x86/kvm/ioapic.h                    |  16 +-
 arch/x86/kvm/irq.c                       |   2 +
 arch/x86/kvm/lapic.c                     |   8 +-
 arch/x86/kvm/lapic.h                     |  15 +-
 arch/x86/kvm/mmu/page_track.c            |   1 +
 arch/x86/kvm/mmu/page_track.h            |   3 +-
 arch/x86/kvm/mmu/spte.h                  |   3 +-
 arch/x86/kvm/msrs.c                      |   5 +
 arch/x86/kvm/msrs.h                      |   3 +-
 arch/x86/kvm/pmu.c                       |   9 +-
 arch/x86/kvm/regs.h                      |  15 +-
 arch/x86/kvm/smm.c                       |   6 +
 arch/x86/kvm/smm.h                       |   2 +-
 arch/x86/kvm/svm/hyperv.c                |   2 +
 arch/x86/kvm/svm/hyperv.h                |   6 +-
 arch/x86/kvm/svm/nested.c                |  30 +++-
 arch/x86/kvm/svm/sev.c                   |  18 ++
 arch/x86/kvm/svm/svm.c                   |  32 ++++
 arch/x86/kvm/svm/svm.h                   |  28 ++-
 arch/x86/kvm/vmx/hyperv.h                |   6 +-
 arch/x86/kvm/vmx/main.c                  |   5 +
 arch/x86/kvm/vmx/nested.c                |  54 +++++-
 arch/x86/kvm/vmx/nested.h                |  19 +-
 arch/x86/kvm/vmx/sgx.c                   |   3 +
 arch/x86/kvm/vmx/sgx.h                   |   3 +-
 arch/x86/kvm/vmx/tdx.c                   |   9 +
 arch/x86/kvm/vmx/vmx.c                   |  11 ++
 arch/x86/kvm/vmx/x86_ops.h               |  24 ++-
 arch/x86/kvm/x86.c                       |  66 ++++++-
 arch/x86/kvm/x86.h                       |  37 ++--
 include/linux/kvm_host.h                 | 215 ++++++++++++++++-------
 scripts/context-analysis-suppression.txt |   1 +
 virt/kvm/dirty_ring.c                    |   2 +
 virt/kvm/eventfd.c                       |   9 +-
 virt/kvm/guest_memfd.c                   |  21 ++-
 virt/kvm/kvm_main.c                      | 183 +++++++++++++------
 virt/kvm/pfncache.c                      |   3 +
 43 files changed, 745 insertions(+), 236 deletions(-)

-- 
2.55.0.1003.g10538fe699-goog