[REPOST PATCH 10/16] selftests: KVM: aarch64: Add KVM EVTYPE filter PMU test

Raghavendra Rao Ananta
2023-02-15T01:08:16Z

KVM doest't allow the guests to modify the filter types
such counting events in nonsecure/secure-EL2, EL3, and
so on. Validate the same by force-configuring the bits
in PMXEVTYPER_EL0, PMEVTYPERn_EL0, and PMCCFILTR_EL0
registers.

The test extends further by trying to create an event
for counting only in EL2 and validates if the counter
is not progressing.

Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
---
.../testing/selftests/kvm/aarch64/vpmu_test.c | 85 +++++++++++++++++++
1 file changed, 85 insertions(+)

diff --git a/tools/testing/selftests/kvm/aarch64/vpmu_test.c b/tools/testing/selftests/kvm/aarch64/vpmu_test.c
index 3dfb770b538e9..5c166df245589 100644
--- a/tools/testing/selftests/kvm/aarch64/vpmu_test.c
+++ b/tools/testing/selftests/kvm/aarch64/vpmu_test.c
@@ -15,6 +15,10 @@
* of allowing or denying the events. The guest validates it by
* checking if it's able to count only the events that are allowed.
*
+ * 3. KVM doesn't allow the guest to count the events attributed with
+ * higher exception levels (EL2, EL3). Verify this functionality by
+ * configuring and trying to count the events for EL2 in the guest.
+ *
* Copyright (c) 2022 Google LLC.
*
*/
@@ -23,6 +27,7 @@
#include <test_util.h>
#include <vgic.h>
#include <asm/perf_event.h>
+#include <linux/arm-smccc.h>
#include <linux/bitfield.h>
#include <linux/bitmap.h>

@@ -259,6 +264,7 @@ struct vpmu_vm {
enum test_stage {
TEST_STAGE_COUNTER_ACCESS = 1,
TEST_STAGE_KVM_EVENT_FILTER,
+ TEST_STAGE_KVM_EVTYPE_FILTER,
};

struct guest_data {
@@ -678,6 +684,70 @@ static void guest_event_filter_test(unsigned long *pmu_filter)
}
}

+static void guest_evtype_filter_test(void)
+{
+ int i;
+ struct pmc_accessor *acc;
+ uint64_t typer, cnt;
+ struct arm_smccc_res res;
+
+ pmu_enable();
+
+ /*
+ * KVM blocks the guests from creating events for counting in Secure/Non-Secure Hyp (EL2),
+ * Monitor (EL3), and Multithreading configuration. It applies the mask
+ * ARMV8_PMU_EVTYPE_MASK against guest accesses to PMXEVTYPER_EL0, PMEVTYPERn_EL0,
+ * and PMCCFILTR_EL0 registers to prevent this. Check if KVM honors this using all possible
+ * ways to configure the EVTYPER.
+ */
+ for (i = 0; i < ARRAY_SIZE(pmc_accessors); i++) {
+ acc = &pmc_accessors[i];
+
+ /* Set all filter bits (31-24), readback, and check against the mask */
+ acc->write_typer(0, 0xff000000);
+ typer = acc->read_typer(0);
+
+ GUEST_ASSERT_2((typer | ARMV8_PMU_EVTYPE_EVENT) == ARMV8_PMU_EVTYPE_MASK,
+ typer | ARMV8_PMU_EVTYPE_EVENT, ARMV8_PMU_EVTYPE_MASK);
+
+ /*
+ * Regardless of ARMV8_PMU_EVTYPE_MASK, KVM sets perf attr.exclude_hv
+ * to not count NS-EL2 events. Verify this functionality by configuring
+ * a NS-EL2 event, for which the couunt shouldn't increment.
+ */
+ typer = ARMV8_PMUV3_PERFCTR_INST_RETIRED;
+ typer |= ARMV8_PMU_INCLUDE_EL2 | ARMV8_PMU_EXCLUDE_EL1 | ARMV8_PMU_EXCLUDE_EL0;
+ acc->write_typer(0, typer);
+ acc->write_cntr(0, 0);
+ enable_counter(0);
+
+ /* Issue a hypercall to enter EL2 and return */
+ memset(&res, 0, sizeof(res));
+ smccc_hvc(ARM_SMCCC_VERSION_FUNC_ID, 0, 0, 0, 0, 0, 0, 0, &res);
+
+ cnt = acc->read_cntr(0);
+ GUEST_ASSERT_3(cnt == 0, cnt, typer, i);
+ }
+
+ /* Check the same sequence for the Cycle counter */
+ write_pmccfiltr(0xff000000);
+ typer = read_pmccfiltr();
+ GUEST_ASSERT_2((typer | ARMV8_PMU_EVTYPE_EVENT) == ARMV8_PMU_EVTYPE_MASK,
+ typer | ARMV8_PMU_EVTYPE_EVENT, ARMV8_PMU_EVTYPE_MASK);
+
+ typer = ARMV8_PMU_INCLUDE_EL2 | ARMV8_PMU_EXCLUDE_EL1 | ARMV8_PMU_EXCLUDE_EL0;
+ write_pmccfiltr(typer);
+ reset_cycle_counter();
+ enable_cycle_counter();
+
+ /* Issue a hypercall to enter EL2 and return */
+ memset(&res, 0, sizeof(res));
+ smccc_hvc(ARM_SMCCC_VERSION_FUNC_ID, 0, 0, 0, 0, 0, 0, 0, &res);
+
+ cnt = read_cycle_counter();
+ GUEST_ASSERT_2(cnt == 0, cnt, typer);
+}
+
static void guest_code(void)
{
switch (guest_data.test_stage) {
@@ -687,6 +757,9 @@ static void guest_code(void)
case TEST_STAGE_KVM_EVENT_FILTER:
guest_event_filter_test(guest_data.pmu_filter);
break;
+ case TEST_STAGE_KVM_EVTYPE_FILTER:
+ guest_evtype_filter_test();
+ break;
default:
GUEST_ASSERT_1(0, guest_data.test_stage);
}
@@ -1014,10 +1087,22 @@ static void run_kvm_event_filter_test(void)
run_kvm_event_filter_error_tests();
}

+static void run_kvm_evtype_filter_test(void)
+{
+ struct vpmu_vm *vpmu_vm;
+
+ guest_data.test_stage = TEST_STAGE_KVM_EVTYPE_FILTER;
+
+ vpmu_vm = create_vpmu_vm(guest_code, NULL);
+ run_vcpu(vpmu_vm->vcpu);
+ destroy_vpmu_vm(vpmu_vm);
+}
+
static void run_tests(uint64_t pmcr_n)
{
run_counter_access_tests(pmcr_n);
run_kvm_event_filter_test();
+ run_kvm_evtype_filter_test();
}

/*
--
2.39.1.581.gbfd45094c4-goog