PMU fixes and cleanups. The highlight is a fix for a double-overflow PMI bug
when KVM manually emulates counter events, which was made mostly benign by
commit a16eb25b09c0 ("KVM: x86: Mask LVTPC when handling a PMI"), but is still
a bug.
Note, the "Track emulated counter events instead of previous counter" fix
breaks the PMU KVM-Unit-Test due to a long-standing "bug" in perf[*]. If need
be, it's trivial to fudge around the shortcomings in the KUT code, I just
haven't carved out time to push things along.
[*] https://lore.kernel.org/all/20231107183605.409588-1-seanjc@xxxxxxxxxx
The following changes since commit e9e60c82fe391d04db55a91c733df4a017c28b2f:
selftests/kvm: fix compilation on non-x86_64 platforms (2023-11-21 11:58:25 -0500)
are available in the Git repository at:
https://github.com/kvm-x86/linux.git tags/kvm-x86-pmu-6.8
for you to fetch changes up to fd89499a5151d197ba30f7b801f6d8f4646cf446:
KVM: x86/pmu: Track emulated counter events instead of previous counter (2023-11-30 12:52:55 -0800)
----------------------------------------------------------------
KVM x86 PMU changes for 6.8:
- Fix a variety of bugs where KVM fail to stop/reset counters and other state
prior to refreshing the vPMU model.
- Fix a double-overflow PMU bug by tracking emulated counter events using a
dedicated field instead of snapshotting the "previous" counter. If the
hardware PMC count triggers overflow that is recognized in the same VM-Exit
that KVM manually bumps an event count, KVM would pend PMIs for both the
hardware-triggered overflow and for KVM-triggered overflow.
----------------------------------------------------------------
Sean Christopherson (6):
KVM: x86/pmu: Move PMU reset logic to common x86 code
KVM: x86/pmu: Reset the PMU, i.e. stop counters, before refreshing
KVM: x86/pmu: Stop calling kvm_pmu_reset() at RESET (it's redundant)
KVM: x86/pmu: Remove manual clearing of fields in kvm_pmu_init()
KVM: x86/pmu: Update sample period in pmc_write_counter()
KVM: x86/pmu: Track emulated counter events instead of previous counter
arch/x86/include/asm/kvm-x86-pmu-ops.h | 2 +-
arch/x86/include/asm/kvm_host.h | 17 +++-
arch/x86/kvm/pmu.c | 140 +++++++++++++++++++++++++++------
arch/x86/kvm/pmu.h | 47 +----------
arch/x86/kvm/svm/pmu.c | 17 ----
arch/x86/kvm/vmx/pmu_intel.c | 22 ------
arch/x86/kvm/x86.c | 1 -
7 files changed, 137 insertions(+), 109 deletions(-)
