On a VM with PMU disabled via KVM_CAP_PMU_CONFIG, the PMU will not be
usable by the guest. On Intel, this causes a #GP. And on AMD, the
counters no longer increment.
KVM_CAP_PMU_CONFIG must be invoked on a VM prior to creating VCPUs.
Signed-off-by: David Dunn <daviddunn@xxxxxxxxxx>
---
.../kvm/x86_64/pmu_event_filter_test.c | 35 +++++++++++++++++++
1 file changed, 35 insertions(+)
diff --git a/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c b/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
index c715adcbd487..40fecaa4ea9f 100644
--- a/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
+++ b/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
@@ -325,6 +325,39 @@ static void test_not_member_allow_list(struct kvm_vm *vm)
TEST_ASSERT(!count, "Disallowed PMU Event is counting");
}
+/*
+ * Verify KVM_PMU_CONFIG_DISABLE prevents the use of the PMU.
+ *
+ * Note that KVM_CAP_PMU_CONFIG must be invoked prior to creating VCPUs.
+ */
+static void test_pmu_config_disable(void (*guest_code)(void))
+{
+ int r;
+ struct kvm_vm *vm;
+ struct kvm_enable_cap cap = { 0 };
+ bool sane;
+
+ r = kvm_check_cap(KVM_CAP_PMU_CONFIG);
+ if ((r & KVM_PMU_CONFIG_DISABLE) == 0)
+ return;
+
+ vm = vm_create_without_vcpus(VM_MODE_DEFAULT, DEFAULT_GUEST_PHY_PAGES);
+
+ cap.cap = KVM_CAP_PMU_CONFIG;
+ cap.args[0] = KVM_PMU_CONFIG_DISABLE;
+ r = vm_enable_cap(vm, &cap);
+ TEST_ASSERT(r == 0, "Failed KVM_PMU_CONFIG_DISABLE.");
+
+ vm_vcpu_add_default(vm, VCPU_ID, guest_code);
+ vm_init_descriptor_tables(vm);
+ vcpu_init_descriptor_tables(vm, VCPU_ID);
+
+ sane = sanity_check_pmu(vm);
+ TEST_ASSERT(!sane, "Guest should not see PMU when disabled.");
+
+ kvm_vm_free(vm);
+}
+
/*
* Check for a non-zero PMU version, at least one general-purpose
* counter per logical processor, an EBX bit vector of length greater
@@ -430,5 +463,7 @@ int main(int argc, char *argv[])
kvm_vm_free(vm);
+ test_pmu_config_disable(guest_code);
+
return 0;
}
--
2.35.0.rc0.227.g00780c9af4-goog
