[PATCH v9 08/16] KVM: arm64: selftests: Cover PMU state in MDCR_EL2

[Akihiko Odaki]

Add MDCR_EL2 coverage to vpmu_counter_access when EL2 is available.

For each configured PMCR_EL0.N value, verify that an arbitrary HPMN
value, including one above the configured counter count, round-trips
through KVM_SET_ONE_REG and survives SET_NR_COUNTERS. Also verify that
HPME can be toggled without disturbing HPMN and that KVM_ARM_VCPU_INIT
resets HPMN from the configured count.

Assisted-by: Codex:gpt-5.5
Signed-off-by: Akihiko Odaki <odaki@xxxxxxxxxxxxxxxxxxxxxx>
---
 .../selftests/kvm/arm64/vpmu_counter_access.c      | 90 ++++++++++++++++++++--
 1 file changed, 85 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/kvm/arm64/vpmu_counter_access.c b/tools/testing/selftests/kvm/arm64/vpmu_counter_access.c
index 3b5bb421f401..73f04e4c6ca3 100644
--- a/tools/testing/selftests/kvm/arm64/vpmu_counter_access.c
+++ b/tools/testing/selftests/kvm/arm64/vpmu_counter_access.c
@@ -25,6 +25,14 @@
 /* The cycle counter bit position that's common among the PMU registers */
 #define ARMV8_PMU_CYCLE_IDX		31
 
+#ifndef MDCR_EL2_HPMN
+#define MDCR_EL2_HPMN			GENMASK_ULL(4, 0)
+#endif
+
+#ifndef MDCR_EL2_HPME
+#define MDCR_EL2_HPME			BIT_ULL(7)
+#endif
+
 struct vpmu_vm {
 	struct kvm_vm *vm;
 	struct kvm_vcpu *vcpu;
@@ -466,15 +474,12 @@ static void guest_code_done(void)
 	GUEST_DONE();
 }
 
-static void test_create_vpmu_vm_with_nr_counters(unsigned int nr_counters, bool expect_fail)
+static void set_nr_counters(struct kvm_vcpu *vcpu,
+			    unsigned int nr_counters, bool expect_fail)
 {
-	struct kvm_vcpu *vcpu;
 	unsigned int prev;
 	int ret;
 
-	create_vpmu_vm(guest_code);
-	vcpu = vpmu_vm.vcpu;
-
 	prev = get_pmcr_n(vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(SYS_PMCR_EL0)));
 
 	ret = __vcpu_device_attr_set(vcpu, KVM_ARM_VCPU_PMU_V3_CTRL,
@@ -486,6 +491,17 @@ static void test_create_vpmu_vm_with_nr_counters(unsigned int nr_counters, bool
 			    nr_counters, prev);
 	else
 		TEST_ASSERT(!ret, KVM_IOCTL_ERROR(KVM_SET_DEVICE_ATTR, ret));
+}
+
+static void test_create_vpmu_vm_with_nr_counters(unsigned int nr_counters,
+						 bool expect_fail)
+{
+	struct kvm_vcpu *vcpu;
+
+	create_vpmu_vm(guest_code);
+	vcpu = vpmu_vm.vcpu;
+
+	set_nr_counters(vcpu, nr_counters, expect_fail);
 
 	vcpu_device_attr_set(vcpu, KVM_ARM_VCPU_PMU_V3_CTRL, KVM_ARM_VCPU_PMU_V3_INIT, NULL);
 }
@@ -588,6 +604,69 @@ static void run_pmregs_validity_test(u64 pmcr_n)
 	destroy_vpmu_vm();
 }
 
+static void run_mdcr_el2_validity_test(u64 pmcr_n)
+{
+	struct kvm_vcpu_init init;
+	struct kvm_vcpu *vcpu;
+	u64 expected_mdcr, mdcr;
+
+	pr_debug("MDCR_EL2 test with pmcr_n %lu\n", pmcr_n);
+
+	create_vpmu_vm(guest_code);
+	if (!vm_supports_el2(vpmu_vm.vm)) {
+		destroy_vpmu_vm();
+		return;
+	}
+
+	vcpu = vpmu_vm.vcpu;
+
+	mdcr = vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(SYS_MDCR_EL2));
+	expected_mdcr = u64_replace_bits(mdcr, FIELD_MAX(MDCR_EL2_HPMN),
+					 MDCR_EL2_HPMN);
+	vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_MDCR_EL2),
+		     expected_mdcr);
+
+	mdcr = vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(SYS_MDCR_EL2));
+	TEST_ASSERT(mdcr == expected_mdcr,
+		    "MDCR_EL2 was not properly updated after HPMN write (expected 0x%lx, got 0x%lx)",
+		    expected_mdcr, mdcr);
+
+	set_nr_counters(vcpu, pmcr_n, false);
+
+	mdcr = vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(SYS_MDCR_EL2));
+	TEST_ASSERT(mdcr == expected_mdcr,
+		    "MDCR_EL2 changed after PMU_V3_SET_NR_COUNTERS (expected 0x%lx, got 0x%lx)",
+		    expected_mdcr, mdcr);
+
+	vcpu_device_attr_set(vcpu, KVM_ARM_VCPU_PMU_V3_CTRL,
+			     KVM_ARM_VCPU_PMU_V3_INIT, NULL);
+
+	mdcr = vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(SYS_MDCR_EL2));
+	TEST_ASSERT(mdcr == expected_mdcr,
+		    "MDCR_EL2 changed after PMU_V3_INIT (expected 0x%lx, got 0x%lx)",
+		    expected_mdcr, mdcr);
+
+	expected_mdcr = mdcr ^ MDCR_EL2_HPME;
+	vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_MDCR_EL2),
+		     expected_mdcr);
+
+	mdcr = vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(SYS_MDCR_EL2));
+	TEST_ASSERT(mdcr == expected_mdcr,
+		    "MDCR_EL2 was not properly updated after HPME write (expected 0x%lx, got 0x%lx)",
+		    expected_mdcr, mdcr);
+
+	kvm_get_default_vcpu_target(vpmu_vm.vm, &init);
+	init.features[0] |= (1 << KVM_ARM_VCPU_PMU_V3);
+	aarch64_vcpu_setup(vcpu, &init);
+
+	mdcr = vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(SYS_MDCR_EL2));
+	TEST_ASSERT(FIELD_GET(MDCR_EL2_HPMN, mdcr) == pmcr_n,
+		    "MDCR_EL2.HPMN is not reset after INIT (expected %lu, got %lu)",
+		    pmcr_n, FIELD_GET(MDCR_EL2_HPMN, mdcr));
+
+	destroy_vpmu_vm();
+}
+
 /*
  * Create a guest with one vCPU, and attempt to set the PMCR_EL0.N for
  * the vCPU to @pmcr_n, which is larger than the host value.
@@ -672,6 +751,7 @@ int main(void)
 	for (i = 0; i <= pmcr_n; i++) {
 		run_access_test(i);
 		run_pmregs_validity_test(i);
+		run_mdcr_el2_validity_test(i);
 	}
 
 	for (i = pmcr_n + 1; i < ARMV8_PMU_MAX_COUNTERS; i++)

-- 
2.55.0