[PATCH v5 00/13] KVM: x86/pmu: Add support for AMD Host-Only/Guest-Only bits

Yosry Ahmed
2026-04-30T20:27:59Z

v5 of Jim and myself's series adding support for AMD's Host-Only and
Guest-Only performance counter eventsel bits in KVM's mediated PMU
passthrough implementation.

These bits allow an nSVM-enabled guest to configure performance counters
that count only during L1 execution (Host-Only) or only during L2 execution
(Guest-Only).

KVM updates the hardware event selector ENABLE bit at nested transitions
and EFER.SVME changes such that counters only count in the appropriate
mode.

The series grew significantly since v4, as it now includes semi-related
nSVM fixups and selftests cleanups needed for the series. I think parts
of this series can land independently (patches 1-6 and patches 10-12),
but then the remaining series would depend on both.

v4 -> v5:
- Dropped moving leave_guest_mode() and enter_guest_mode() definitions,
since the calls to update the vPMU no longer happen within these
functions.
- Add PMU helpers refactoring to facilitate SVM usage.
- Added nested SVM fixups to count VMRUN correctly in guest mode when
Host-Only/Guest-Only support is enabled [Jim/Sean].
- Update the vPMU synchronously on nested VM-Enter/VM-Exit and EFER.SVME
changes, such that counter enablement is reevaluated before the
instructions are counted, as the vPMU counts based on the vCPU state
at instruction retirement (e.g. using new EFER value when EFER.SVME
changes) [Jim/Sean].
- Keep deferring vPMU updates using KVM_REQ_PMU in the
svm_leave_nested() path to avoid KVM potentially consuming stale
state [Sean].
- Use a single PMU callback for reprogramming counters instead of a
per-counter callback [Sean].
- Move the bitmap tracking counters into SVM code. The generic vPMU code
now only exposes an API to reprogram counters, and an SVM wrapper uses
it on nested transitions [Sean].
- Drop the manual stack-alignment fixes in the vPMU selftest, instead
rework L2 stack setup in all nested selftests to reuse the allocation
and alignment logic used by L1, and completely drop L1-provided stacks
for L2 [Sean].

Jim Mattson (2):
KVM: x86/pmu: Allow Host-Only/Guest-Only bits with nSVM and mediated
PMU
KVM: selftests: Add svm_pmu_host_guest_test for Host-Only/Guest-Only
bits

Yosry Ahmed (11):
KVM: nSVM: Stop leaking single-stepping on VMRUN into L2
KVM: nSVM: Bail early out of VMRUN emulation if advancing RIP fails
KVM: nSVM: Move VMRUN instruction retirement after entering guest mode
KVM: x86: Move enable_pmu/enable_mediated_pmu to pmu.h and pmu.c
KVM: x86/pmu: Rename reprogram_counters() to clarify usage
KVM: x86/pmu: Do a single atomic OR when reprogramming counters
KVM: x86/pmu: Disable counters based on Host-Only/Guest-Only bits in
SVM
KVM: x86/pmu: Reprogram Host/Guest-Only counters on nested transitions
KVM: selftests: Refactor allocating guest stack into a helper
KVM: selftests: Allocate a dedicated guest page for x86 L2 guest stack
KVM: selftests: Drop L1-provided stacks for L2 guests on x86

arch/x86/include/asm/kvm-x86-pmu-ops.h | 1 +
arch/x86/include/asm/kvm_host.h | 2 +
arch/x86/include/asm/perf_event.h | 2 +
arch/x86/kvm/pmu.c | 19 +-
arch/x86/kvm/pmu.h | 28 ++-
arch/x86/kvm/svm/nested.c | 43 +++-
arch/x86/kvm/svm/pmu.c | 53 +++++
arch/x86/kvm/svm/svm.c | 2 +
arch/x86/kvm/svm/svm.h | 33 +++
arch/x86/kvm/vmx/pmu_intel.c | 2 +-
arch/x86/kvm/x86.c | 17 +-
arch/x86/kvm/x86.h | 3 -
tools/testing/selftests/kvm/Makefile.kvm | 1 +
tools/testing/selftests/kvm/include/x86/pmu.h | 6 +
.../selftests/kvm/include/x86/processor.h | 2 +
.../selftests/kvm/include/x86/svm_util.h | 5 +-
tools/testing/selftests/kvm/include/x86/vmx.h | 4 +-
.../testing/selftests/kvm/lib/x86/memstress.c | 19 +-
.../testing/selftests/kvm/lib/x86/processor.c | 45 ++--
tools/testing/selftests/kvm/lib/x86/svm.c | 6 +-
tools/testing/selftests/kvm/lib/x86/vmx.c | 6 +-
.../selftests/kvm/x86/aperfmperf_test.c | 9 +-
.../kvm/x86/evmcs_smm_controls_test.c | 5 +-
.../testing/selftests/kvm/x86/hyperv_evmcs.c | 6 +-
.../selftests/kvm/x86/hyperv_svm_test.c | 6 +-
.../selftests/kvm/x86/kvm_buslock_test.c | 9 +-
.../selftests/kvm/x86/nested_close_kvm_test.c | 12 +-
.../selftests/kvm/x86/nested_dirty_log_test.c | 8 +-
.../selftests/kvm/x86/nested_emulation_test.c | 4 +-
.../kvm/x86/nested_exceptions_test.c | 9 +-
.../kvm/x86/nested_invalid_cr3_test.c | 10 +-
.../kvm/x86/nested_tsc_adjust_test.c | 10 +-
.../kvm/x86/nested_tsc_scaling_test.c | 10 +-
.../kvm/x86/nested_vmsave_vmload_test.c | 6 +-
tools/testing/selftests/kvm/x86/smm_test.c | 8 +-
tools/testing/selftests/kvm/x86/state_test.c | 11 +-
.../selftests/kvm/x86/svm_int_ctl_test.c | 5 +-
.../selftests/kvm/x86/svm_lbr_nested_state.c | 6 +-
.../kvm/x86/svm_nested_clear_efer_svme.c | 7 +-
.../kvm/x86/svm_nested_shutdown_test.c | 5 +-
.../kvm/x86/svm_nested_soft_inject_test.c | 6 +-
.../selftests/kvm/x86/svm_nested_vmcb12_gpa.c | 13 +-
.../kvm/x86/svm_pmu_host_guest_test.c | 216 ++++++++++++++++++
.../selftests/kvm/x86/svm_vmcall_test.c | 5 +-
.../kvm/x86/triple_fault_event_test.c | 9 +-
.../selftests/kvm/x86/vmx_apic_access_test.c | 5 +-
.../kvm/x86/vmx_apicv_updates_test.c | 4 +-
.../kvm/x86/vmx_invalid_nested_guest_state.c | 6 +-
.../kvm/x86/vmx_nested_la57_state_test.c | 5 +-
.../kvm/x86/vmx_preemption_timer_test.c | 5 +-
50 files changed, 484 insertions(+), 235 deletions(-)
create mode 100644 tools/testing/selftests/kvm/x86/svm_pmu_host_guest_test.c

base-commit: 85f871f6ba46f20d7fbc0b016b4db648c33220dd
--
2.54.0.545.g6539524ca2-goog