[PATCH v9 16/16] KVM: arm64: selftests: Test PMU_V3_FIXED_COUNTERS_ONLY
Akihiko Odaki
odaki at rsg.ci.i.u-tokyo.ac.jp
Sun Jul 19 22:38:10 PDT 2026
Assert the following:
- FIXED_COUNTERS_ONLY is unset at initialization.
- FIXED_COUNTERS_ONLY can be set.
- Setting an event filter when FIXED_COUNTERS_ONLY has already been set
results in EBUSY.
- Setting FIXED_COUNTERS_ONLY when an event filter has already been set
results in EBUSY.
- Setting FIXED_COUNTERS_ONLY when a VCPU has already run results in
EBUSY.
Run the existing PMU and MDCR_EL2 tests in fixed-only mode. Verify that
enabling the mode preserves the userspace MDCR_EL2 value until a
subsequent KVM_ARM_VCPU_INIT resets HPMN to zero.
Assisted-by: Codex:gpt-5.5
Signed-off-by: Akihiko Odaki <odaki at rsg.ci.i.u-tokyo.ac.jp>
---
.../selftests/kvm/arm64/vpmu_counter_access.c | 166 +++++++++++++++++----
1 file changed, 137 insertions(+), 29 deletions(-)
diff --git a/tools/testing/selftests/kvm/arm64/vpmu_counter_access.c b/tools/testing/selftests/kvm/arm64/vpmu_counter_access.c
index 73f04e4c6ca3..b5f8ce8d3451 100644
--- a/tools/testing/selftests/kvm/arm64/vpmu_counter_access.c
+++ b/tools/testing/selftests/kvm/arm64/vpmu_counter_access.c
@@ -411,12 +411,7 @@ static void create_vpmu_vm(void *guest_code)
{
struct kvm_vcpu_init init;
u8 pmuver, ec;
- u64 dfr0, irq = 23;
- struct kvm_device_attr irq_attr = {
- .group = KVM_ARM_VCPU_PMU_V3_CTRL,
- .attr = KVM_ARM_VCPU_PMU_V3_IRQ,
- .addr = (u64)&irq,
- };
+ u64 dfr0;
/* The test creates the vpmu_vm multiple times. Ensure a clean state */
memset(&vpmu_vm, 0, sizeof(vpmu_vm));
@@ -442,8 +437,6 @@ static void create_vpmu_vm(void *guest_code)
TEST_ASSERT(pmuver != ID_AA64DFR0_EL1_PMUVer_IMP_DEF &&
pmuver >= ID_AA64DFR0_EL1_PMUVer_IMP,
"Unexpected PMUVER (0x%x) on the vCPU with PMUv3", pmuver);
-
- vcpu_ioctl(vpmu_vm.vcpu, KVM_SET_DEVICE_ATTR, &irq_attr);
}
static void destroy_vpmu_vm(void)
@@ -494,13 +487,22 @@ static void set_nr_counters(struct kvm_vcpu *vcpu,
}
static void test_create_vpmu_vm_with_nr_counters(unsigned int nr_counters,
+ bool fixed_counters_only,
bool expect_fail)
{
struct kvm_vcpu *vcpu;
+ u64 irq = 23;
create_vpmu_vm(guest_code);
vcpu = vpmu_vm.vcpu;
+ if (fixed_counters_only)
+ vcpu_device_attr_set(vcpu, KVM_ARM_VCPU_PMU_V3_CTRL,
+ KVM_ARM_VCPU_PMU_V3_FIXED_COUNTERS_ONLY, NULL);
+
+ vcpu_device_attr_set(vcpu, KVM_ARM_VCPU_PMU_V3_CTRL,
+ KVM_ARM_VCPU_PMU_V3_IRQ, &irq);
+
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);
@@ -510,15 +512,15 @@ static void test_create_vpmu_vm_with_nr_counters(unsigned int nr_counters,
* Create a guest with one vCPU, set the PMCR_EL0.N for the vCPU to @pmcr_n,
* and run the test.
*/
-static void run_access_test(u64 pmcr_n)
+static void run_access_test(u64 pmcr_n, bool fixed_counters_only)
{
u64 sp;
struct kvm_vcpu *vcpu;
struct kvm_vcpu_init init;
- pr_debug("Test with pmcr_n %lu\n", pmcr_n);
+ pr_debug("Test with pmcr_n %lu, fixed_counters_only %d\n", pmcr_n, fixed_counters_only);
- test_create_vpmu_vm_with_nr_counters(pmcr_n, false);
+ test_create_vpmu_vm_with_nr_counters(pmcr_n, fixed_counters_only, false);
vcpu = vpmu_vm.vcpu;
/* Save the initial sp to restore them later to run the guest again */
@@ -552,14 +554,14 @@ static struct pmreg_sets validity_check_reg_sets[] = {
* Create a VM, and check if KVM handles the userspace accesses of
* the PMU register sets in @validity_check_reg_sets[] correctly.
*/
-static void run_pmregs_validity_test(u64 pmcr_n)
+static void run_pmregs_validity_test(u64 pmcr_n, bool fixed_counters_only)
{
int i;
struct kvm_vcpu *vcpu;
u64 set_reg_id, clr_reg_id, reg_val;
u64 valid_counters_mask, max_counters_mask;
- test_create_vpmu_vm_with_nr_counters(pmcr_n, false);
+ test_create_vpmu_vm_with_nr_counters(pmcr_n, fixed_counters_only, false);
vcpu = vpmu_vm.vcpu;
valid_counters_mask = get_counters_mask(pmcr_n);
@@ -604,13 +606,15 @@ static void run_pmregs_validity_test(u64 pmcr_n)
destroy_vpmu_vm();
}
-static void run_mdcr_el2_validity_test(u64 pmcr_n)
+static void run_mdcr_el2_validity_test(u64 pmcr_n, bool fixed_counters_only)
{
struct kvm_vcpu_init init;
struct kvm_vcpu *vcpu;
u64 expected_mdcr, mdcr;
+ u64 irq = 23;
- pr_debug("MDCR_EL2 test with pmcr_n %lu\n", pmcr_n);
+ pr_debug("MDCR_EL2 test with pmcr_n %lu, fixed_counters_only %d\n",
+ pmcr_n, fixed_counters_only);
create_vpmu_vm(guest_code);
if (!vm_supports_el2(vpmu_vm.vm)) {
@@ -631,6 +635,16 @@ static void run_mdcr_el2_validity_test(u64 pmcr_n)
"MDCR_EL2 was not properly updated after HPMN write (expected 0x%lx, got 0x%lx)",
expected_mdcr, mdcr);
+ if (fixed_counters_only) {
+ vcpu_device_attr_set(vcpu, KVM_ARM_VCPU_PMU_V3_CTRL,
+ KVM_ARM_VCPU_PMU_V3_FIXED_COUNTERS_ONLY, NULL);
+
+ mdcr = vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(SYS_MDCR_EL2));
+ TEST_ASSERT(mdcr == expected_mdcr,
+ "MDCR_EL2 changed after PMU_V3_FIXED_COUNTERS_ONLY (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));
@@ -638,6 +652,9 @@ static void run_mdcr_el2_validity_test(u64 pmcr_n)
"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_IRQ, &irq);
+
vcpu_device_attr_set(vcpu, KVM_ARM_VCPU_PMU_V3_CTRL,
KVM_ARM_VCPU_PMU_V3_INIT, NULL);
@@ -672,11 +689,11 @@ static void run_mdcr_el2_validity_test(u64 pmcr_n)
* the vCPU to @pmcr_n, which is larger than the host value.
* The attempt should fail as @pmcr_n is too big to set for the vCPU.
*/
-static void run_error_test(u64 pmcr_n)
+static void run_error_test(u64 pmcr_n, bool fixed_counters_only)
{
pr_debug("Error test with pmcr_n %lu (larger than the host)\n", pmcr_n);
- test_create_vpmu_vm_with_nr_counters(pmcr_n, true);
+ test_create_vpmu_vm_with_nr_counters(pmcr_n, fixed_counters_only, true);
destroy_vpmu_vm();
}
@@ -737,25 +754,116 @@ static void test_set_nr_counters_after_vcpu_run(void)
kvm_vm_free(vm);
}
-int main(void)
+static void test_config(u64 pmcr_n, bool fixed_counters_only)
+{
+ u64 i;
+
+ for (i = 0; i <= pmcr_n; i++) {
+ run_access_test(i, fixed_counters_only);
+ run_pmregs_validity_test(i, fixed_counters_only);
+ run_mdcr_el2_validity_test(i, fixed_counters_only);
+ }
+
+ for (i = pmcr_n + 1; i < ARMV8_PMU_MAX_COUNTERS; i++)
+ run_error_test(i, fixed_counters_only);
+}
+
+static void test_fixed_counters_only(void)
{
- u64 i, pmcr_n;
+ struct kvm_pmu_event_filter filter = { .nevents = 0 };
+ struct kvm_vm *vm;
+ struct kvm_vcpu *running_vcpu;
+ struct kvm_vcpu *stopped_vcpu;
+ struct kvm_vcpu_init init;
+ int ret;
+ u64 irq = 23;
+
+ create_vpmu_vm(guest_code);
+ ret = __vcpu_has_device_attr(vpmu_vm.vcpu, KVM_ARM_VCPU_PMU_V3_CTRL,
+ KVM_ARM_VCPU_PMU_V3_FIXED_COUNTERS_ONLY);
+ if (ret) {
+ TEST_ASSERT(ret == -1 && errno == ENXIO,
+ KVM_IOCTL_ERROR(KVM_HAS_DEVICE_ATTR, ret));
+ destroy_vpmu_vm();
+ return;
+ }
+
+ /* Assert that FIXED_COUNTERS_ONLY is unset at initialization. */
+ ret = __vcpu_device_attr_get(vpmu_vm.vcpu, KVM_ARM_VCPU_PMU_V3_CTRL,
+ KVM_ARM_VCPU_PMU_V3_FIXED_COUNTERS_ONLY, NULL);
+ TEST_ASSERT(ret == -1 && errno == ENXIO,
+ KVM_IOCTL_ERROR(KVM_GET_DEVICE_ATTR, ret));
+
+ /* Assert that setting FIXED_COUNTERS_ONLY succeeds. */
+ vcpu_device_attr_set(vpmu_vm.vcpu, KVM_ARM_VCPU_PMU_V3_CTRL,
+ KVM_ARM_VCPU_PMU_V3_FIXED_COUNTERS_ONLY, NULL);
+
+ /* Assert that FIXED_COUNTERS_ONLY is set. */
+ vcpu_device_attr_get(vpmu_vm.vcpu, KVM_ARM_VCPU_PMU_V3_CTRL,
+ KVM_ARM_VCPU_PMU_V3_FIXED_COUNTERS_ONLY, NULL);
+
+ /*
+ * Setting an event filter when FIXED_COUNTERS_ONLY has already been set
+ * results in EBUSY.
+ */
+ ret = __vcpu_device_attr_set(vpmu_vm.vcpu, KVM_ARM_VCPU_PMU_V3_CTRL,
+ KVM_ARM_VCPU_PMU_V3_FILTER, &filter);
+ TEST_ASSERT(ret == -1 && errno == EBUSY,
+ KVM_IOCTL_ERROR(KVM_SET_DEVICE_ATTR, ret));
+
+ destroy_vpmu_vm();
+
+ create_vpmu_vm(guest_code);
+
+ /*
+ * Assert that setting FIXED_COUNTERS_ONLY when an event filter has
+ * already been set results in EBUSY.
+ */
+ vcpu_device_attr_set(vpmu_vm.vcpu, KVM_ARM_VCPU_PMU_V3_CTRL,
+ KVM_ARM_VCPU_PMU_V3_FILTER, &filter);
+
+ ret = __vcpu_device_attr_set(vpmu_vm.vcpu, KVM_ARM_VCPU_PMU_V3_CTRL,
+ KVM_ARM_VCPU_PMU_V3_FIXED_COUNTERS_ONLY, NULL);
+ TEST_ASSERT(ret == -1 && errno == EBUSY,
+ KVM_IOCTL_ERROR(KVM_SET_DEVICE_ATTR, ret));
+
+ destroy_vpmu_vm();
+
+ /*
+ * Assert that setting FIXED_COUNTERS_ONLY when a VCPU has already run
+ * results in EBUSY.
+ */
+ vm = vm_create(2);
+ vm_ioctl(vm, KVM_ARM_PREFERRED_TARGET, &init);
+ init.features[0] |= (1 << KVM_ARM_VCPU_PMU_V3);
+ running_vcpu = aarch64_vcpu_add(vm, 0, &init, guest_code_done);
+ stopped_vcpu = aarch64_vcpu_add(vm, 1, &init, guest_code_done);
+ kvm_arch_vm_finalize_vcpus(vm);
+ vcpu_device_attr_set(running_vcpu, KVM_ARM_VCPU_PMU_V3_CTRL,
+ KVM_ARM_VCPU_PMU_V3_IRQ, &irq);
+ vcpu_device_attr_set(running_vcpu, KVM_ARM_VCPU_PMU_V3_CTRL,
+ KVM_ARM_VCPU_PMU_V3_INIT, NULL);
+ vcpu_run(running_vcpu);
+
+ ret = __vcpu_device_attr_set(stopped_vcpu, KVM_ARM_VCPU_PMU_V3_CTRL,
+ KVM_ARM_VCPU_PMU_V3_FIXED_COUNTERS_ONLY, NULL);
+ TEST_ASSERT(ret == -1 && errno == EBUSY,
+ KVM_IOCTL_ERROR(KVM_SET_DEVICE_ATTR, ret));
+
+ kvm_vm_free(vm);
+
+ test_config(0, true);
+}
+int main(void)
+{
TEST_REQUIRE(kvm_has_cap(KVM_CAP_ARM_PMU_V3));
TEST_REQUIRE(kvm_supports_vgic_v3());
TEST_REQUIRE(kvm_supports_nr_counters_attr());
test_set_nr_counters_after_vcpu_run();
-
- pmcr_n = get_pmcr_n_limit();
- 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++)
- run_error_test(i);
+ test_config(get_pmcr_n_limit(), false);
+ test_fixed_counters_only();
return 0;
}
--
2.55.0
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