Merge branch kvm-arm64/pmu_pmcr_n into kvmarm/next

* kvm-arm64/pmu_pmcr_n:
  : User-defined PMC limit, courtesy Raghavendra Rao Ananta
  :
  : Certain VMMs may want to reserve some PMCs for host use while running a
  : KVM guest. This was a bit difficult before, as KVM advertised all
  : supported counters to the guest. Userspace can now limit the number of
  : advertised PMCs by writing to PMCR_EL0.N, as KVM's sysreg and PMU
  : emulation enforce the specified limit for handling guest accesses.
  KVM: selftests: aarch64: vPMU test for validating user accesses
  KVM: selftests: aarch64: vPMU register test for unimplemented counters
  KVM: selftests: aarch64: vPMU register test for implemented counters
  KVM: selftests: aarch64: Introduce vpmu_counter_access test
  tools: Import arm_pmuv3.h
  KVM: arm64: PMU: Allow userspace to limit PMCR_EL0.N for the guest
  KVM: arm64: Sanitize PM{C,I}NTEN{SET,CLR}, PMOVS{SET,CLR} before first run
  KVM: arm64: Add {get,set}_user for PM{C,I}NTEN{SET,CLR}, PMOVS{SET,CLR}
  KVM: arm64: PMU: Set PMCR_EL0.N for vCPU based on the associated PMU
  KVM: arm64: PMU: Add a helper to read a vCPU's PMCR_EL0
  KVM: arm64: Select default PMU in KVM_ARM_VCPU_INIT handler
  KVM: arm64: PMU: Introduce helpers to set the guest's PMU

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

3 files changed, 672 insertions, 0 deletions

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 4de096bbf124..04dfbf06b51e 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -159,6 +159,7 @@ TEST_GEN_PROGS_aarch64 += aarch64/smccc_filter
 TEST_GEN_PROGS_aarch64 += aarch64/vcpu_width_config
 TEST_GEN_PROGS_aarch64 += aarch64/vgic_init
 TEST_GEN_PROGS_aarch64 += aarch64/vgic_irq
+TEST_GEN_PROGS_aarch64 += aarch64/vpmu_counter_access
 TEST_GEN_PROGS_aarch64 += access_tracking_perf_test
 TEST_GEN_PROGS_aarch64 += demand_paging_test
 TEST_GEN_PROGS_aarch64 += dirty_log_test
diff --git a/tools/testing/selftests/kvm/aarch64/vpmu_counter_access.c b/tools/testing/selftests/kvm/aarch64/vpmu_counter_access.c
new file mode 100644
index 000000000000..5ea78986e665
--- /dev/null
+++ b/tools/testing/selftests/kvm/aarch64/vpmu_counter_access.c
@@ -0,0 +1,670 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * vpmu_counter_access - Test vPMU event counter access
+ *
+ * Copyright (c) 2023 Google LLC.
+ *
+ * This test checks if the guest can see the same number of the PMU event
+ * counters (PMCR_EL0.N) that userspace sets, if the guest can access
+ * those counters, and if the guest is prevented from accessing any
+ * other counters.
+ * It also checks if the userspace accesses to the PMU regsisters honor the
+ * PMCR.N value that's set for the guest.
+ * This test runs only when KVM_CAP_ARM_PMU_V3 is supported on the host.
+ */
+#include <kvm_util.h>
+#include <processor.h>
+#include <test_util.h>
+#include <vgic.h>
+#include <perf/arm_pmuv3.h>
+#include <linux/bitfield.h>
+
+/* The max number of the PMU event counters (excluding the cycle counter) */
+#define ARMV8_PMU_MAX_GENERAL_COUNTERS	(ARMV8_PMU_MAX_COUNTERS - 1)
+
+/* The cycle counter bit position that's common among the PMU registers */
+#define ARMV8_PMU_CYCLE_IDX		31
+
+struct vpmu_vm {
+	struct kvm_vm *vm;
+	struct kvm_vcpu *vcpu;
+	int gic_fd;
+};
+
+static struct vpmu_vm vpmu_vm;
+
+struct pmreg_sets {
+	uint64_t set_reg_id;
+	uint64_t clr_reg_id;
+};
+
+#define PMREG_SET(set, clr) {.set_reg_id = set, .clr_reg_id = clr}
+
+static uint64_t get_pmcr_n(uint64_t pmcr)
+{
+	return (pmcr >> ARMV8_PMU_PMCR_N_SHIFT) & ARMV8_PMU_PMCR_N_MASK;
+}
+
+static void set_pmcr_n(uint64_t *pmcr, uint64_t pmcr_n)
+{
+	*pmcr = *pmcr & ~(ARMV8_PMU_PMCR_N_MASK << ARMV8_PMU_PMCR_N_SHIFT);
+	*pmcr |= (pmcr_n << ARMV8_PMU_PMCR_N_SHIFT);
+}
+
+static uint64_t get_counters_mask(uint64_t n)
+{
+	uint64_t mask = BIT(ARMV8_PMU_CYCLE_IDX);
+
+	if (n)
+		mask |= GENMASK(n - 1, 0);
+	return mask;
+}
+
+/* Read PMEVTCNTR<n>_EL0 through PMXEVCNTR_EL0 */
+static inline unsigned long read_sel_evcntr(int sel)
+{
+	write_sysreg(sel, pmselr_el0);
+	isb();
+	return read_sysreg(pmxevcntr_el0);
+}
+
+/* Write PMEVTCNTR<n>_EL0 through PMXEVCNTR_EL0 */
+static inline void write_sel_evcntr(int sel, unsigned long val)
+{
+	write_sysreg(sel, pmselr_el0);
+	isb();
+	write_sysreg(val, pmxevcntr_el0);
+	isb();
+}
+
+/* Read PMEVTYPER<n>_EL0 through PMXEVTYPER_EL0 */
+static inline unsigned long read_sel_evtyper(int sel)
+{
+	write_sysreg(sel, pmselr_el0);
+	isb();
+	return read_sysreg(pmxevtyper_el0);
+}
+
+/* Write PMEVTYPER<n>_EL0 through PMXEVTYPER_EL0 */
+static inline void write_sel_evtyper(int sel, unsigned long val)
+{
+	write_sysreg(sel, pmselr_el0);
+	isb();
+	write_sysreg(val, pmxevtyper_el0);
+	isb();
+}
+
+static inline void enable_counter(int idx)
+{
+	uint64_t v = read_sysreg(pmcntenset_el0);
+
+	write_sysreg(BIT(idx) | v, pmcntenset_el0);
+	isb();
+}
+
+static inline void disable_counter(int idx)
+{
+	uint64_t v = read_sysreg(pmcntenset_el0);
+
+	write_sysreg(BIT(idx) | v, pmcntenclr_el0);
+	isb();
+}
+
+static void pmu_disable_reset(void)
+{
+	uint64_t pmcr = read_sysreg(pmcr_el0);
+
+	/* Reset all counters, disabling them */
+	pmcr &= ~ARMV8_PMU_PMCR_E;
+	write_sysreg(pmcr | ARMV8_PMU_PMCR_P, pmcr_el0);
+	isb();
+}
+
+#define RETURN_READ_PMEVCNTRN(n) \
+	return read_sysreg(pmevcntr##n##_el0)
+static unsigned long read_pmevcntrn(int n)
+{
+	PMEVN_SWITCH(n, RETURN_READ_PMEVCNTRN);
+	return 0;
+}
+
+#define WRITE_PMEVCNTRN(n) \
+	write_sysreg(val, pmevcntr##n##_el0)
+static void write_pmevcntrn(int n, unsigned long val)
+{
+	PMEVN_SWITCH(n, WRITE_PMEVCNTRN);
+	isb();
+}
+
+#define READ_PMEVTYPERN(n) \
+	return read_sysreg(pmevtyper##n##_el0)
+static unsigned long read_pmevtypern(int n)
+{
+	PMEVN_SWITCH(n, READ_PMEVTYPERN);
+	return 0;
+}
+
+#define WRITE_PMEVTYPERN(n) \
+	write_sysreg(val, pmevtyper##n##_el0)
+static void write_pmevtypern(int n, unsigned long val)
+{
+	PMEVN_SWITCH(n, WRITE_PMEVTYPERN);
+	isb();
+}
+
+/*
+ * The pmc_accessor structure has pointers to PMEV{CNTR,TYPER}<n>_EL0
+ * accessors that test cases will use. Each of the accessors will
+ * either directly reads/writes PMEV{CNTR,TYPER}<n>_EL0
+ * (i.e. {read,write}_pmev{cnt,type}rn()), or reads/writes them through
+ * PMXEV{CNTR,TYPER}_EL0 (i.e. {read,write}_sel_ev{cnt,type}r()).
+ *
+ * This is used to test that combinations of those accessors provide
+ * the consistent behavior.
+ */
+struct pmc_accessor {
+	/* A function to be used to read PMEVTCNTR<n>_EL0 */
+	unsigned long	(*read_cntr)(int idx);
+	/* A function to be used to write PMEVTCNTR<n>_EL0 */
+	void		(*write_cntr)(int idx, unsigned long val);
+	/* A function to be used to read PMEVTYPER<n>_EL0 */
+	unsigned long	(*read_typer)(int idx);
+	/* A function to be used to write PMEVTYPER<n>_EL0 */
+	void		(*write_typer)(int idx, unsigned long val);
+};
+
+struct pmc_accessor pmc_accessors[] = {
+	/* test with all direct accesses */
+	{ read_pmevcntrn, write_pmevcntrn, read_pmevtypern, write_pmevtypern },
+	/* test with all indirect accesses */
+	{ read_sel_evcntr, write_sel_evcntr, read_sel_evtyper, write_sel_evtyper },
+	/* read with direct accesses, and write with indirect accesses */
+	{ read_pmevcntrn, write_sel_evcntr, read_pmevtypern, write_sel_evtyper },
+	/* read with indirect accesses, and write with direct accesses */
+	{ read_sel_evcntr, write_pmevcntrn, read_sel_evtyper, write_pmevtypern },
+};
+
+/*
+ * Convert a pointer of pmc_accessor to an index in pmc_accessors[],
+ * assuming that the pointer is one of the entries in pmc_accessors[].
+ */
+#define PMC_ACC_TO_IDX(acc)	(acc - &pmc_accessors[0])
+
+#define GUEST_ASSERT_BITMAP_REG(regname, mask, set_expected)			 \
+{										 \
+	uint64_t _tval = read_sysreg(regname);					 \
+										 \
+	if (set_expected)							 \
+		__GUEST_ASSERT((_tval & mask),					 \
+				"tval: 0x%lx; mask: 0x%lx; set_expected: 0x%lx", \
+				_tval, mask, set_expected);			 \
+	else									 \
+		__GUEST_ASSERT(!(_tval & mask),					 \
+				"tval: 0x%lx; mask: 0x%lx; set_expected: 0x%lx", \
+				_tval, mask, set_expected);			 \
+}
+
+/*
+ * Check if @mask bits in {PMCNTEN,PMINTEN,PMOVS}{SET,CLR} registers
+ * are set or cleared as specified in @set_expected.
+ */
+static void check_bitmap_pmu_regs(uint64_t mask, bool set_expected)
+{
+	GUEST_ASSERT_BITMAP_REG(pmcntenset_el0, mask, set_expected);
+	GUEST_ASSERT_BITMAP_REG(pmcntenclr_el0, mask, set_expected);
+	GUEST_ASSERT_BITMAP_REG(pmintenset_el1, mask, set_expected);
+	GUEST_ASSERT_BITMAP_REG(pmintenclr_el1, mask, set_expected);
+	GUEST_ASSERT_BITMAP_REG(pmovsset_el0, mask, set_expected);
+	GUEST_ASSERT_BITMAP_REG(pmovsclr_el0, mask, set_expected);
+}
+
+/*
+ * Check if the bit in {PMCNTEN,PMINTEN,PMOVS}{SET,CLR} registers corresponding
+ * to the specified counter (@pmc_idx) can be read/written as expected.
+ * When @set_op is true, it tries to set the bit for the counter in
+ * those registers by writing the SET registers (the bit won't be set
+ * if the counter is not implemented though).
+ * Otherwise, it tries to clear the bits in the registers by writing
+ * the CLR registers.
+ * Then, it checks if the values indicated in the registers are as expected.
+ */
+static void test_bitmap_pmu_regs(int pmc_idx, bool set_op)
+{
+	uint64_t pmcr_n, test_bit = BIT(pmc_idx);
+	bool set_expected = false;
+
+	if (set_op) {
+		write_sysreg(test_bit, pmcntenset_el0);
+		write_sysreg(test_bit, pmintenset_el1);
+		write_sysreg(test_bit, pmovsset_el0);
+
+		/* The bit will be set only if the counter is implemented */
+		pmcr_n = get_pmcr_n(read_sysreg(pmcr_el0));
+		set_expected = (pmc_idx < pmcr_n) ? true : false;
+	} else {
+		write_sysreg(test_bit, pmcntenclr_el0);
+		write_sysreg(test_bit, pmintenclr_el1);
+		write_sysreg(test_bit, pmovsclr_el0);
+	}
+	check_bitmap_pmu_regs(test_bit, set_expected);
+}
+
+/*
+ * Tests for reading/writing registers for the (implemented) event counter
+ * specified by @pmc_idx.
+ */
+static void test_access_pmc_regs(struct pmc_accessor *acc, int pmc_idx)
+{
+	uint64_t write_data, read_data;
+
+	/* Disable all PMCs and reset all PMCs to zero. */
+	pmu_disable_reset();
+
+	/*
+	 * Tests for reading/writing {PMCNTEN,PMINTEN,PMOVS}{SET,CLR}_EL1.
+	 */
+
+	/* Make sure that the bit in those registers are set to 0 */
+	test_bitmap_pmu_regs(pmc_idx, false);
+	/* Test if setting the bit in those registers works */
+	test_bitmap_pmu_regs(pmc_idx, true);
+	/* Test if clearing the bit in those registers works */
+	test_bitmap_pmu_regs(pmc_idx, false);
+
+	/*
+	 * Tests for reading/writing the event type register.
+	 */
+
+	/*
+	 * Set the event type register to an arbitrary value just for testing
+	 * of reading/writing the register.
+	 * Arm ARM says that for the event from 0x0000 to 0x003F,
+	 * the value indicated in the PMEVTYPER<n>_EL0.evtCount field is
+	 * the value written to the field even when the specified event
+	 * is not supported.
+	 */
+	write_data = (ARMV8_PMU_EXCLUDE_EL1 | ARMV8_PMUV3_PERFCTR_INST_RETIRED);
+	acc->write_typer(pmc_idx, write_data);
+	read_data = acc->read_typer(pmc_idx);
+	__GUEST_ASSERT(read_data == write_data,
+		       "pmc_idx: 0x%lx; acc_idx: 0x%lx; read_data: 0x%lx; write_data: 0x%lx",
+		       pmc_idx, PMC_ACC_TO_IDX(acc), read_data, write_data);
+
+	/*
+	 * Tests for reading/writing the event count register.
+	 */
+
+	read_data = acc->read_cntr(pmc_idx);
+
+	/* The count value must be 0, as it is disabled and reset */
+	__GUEST_ASSERT(read_data == 0,
+		       "pmc_idx: 0x%lx; acc_idx: 0x%lx; read_data: 0x%lx",
+		       pmc_idx, PMC_ACC_TO_IDX(acc), read_data);
+
+	write_data = read_data + pmc_idx + 0x12345;
+	acc->write_cntr(pmc_idx, write_data);
+	read_data = acc->read_cntr(pmc_idx);
+	__GUEST_ASSERT(read_data == write_data,
+		       "pmc_idx: 0x%lx; acc_idx: 0x%lx; read_data: 0x%lx; write_data: 0x%lx",
+		       pmc_idx, PMC_ACC_TO_IDX(acc), read_data, write_data);
+}
+
+#define INVALID_EC	(-1ul)
+uint64_t expected_ec = INVALID_EC;
+
+static void guest_sync_handler(struct ex_regs *regs)
+{
+	uint64_t esr, ec;
+
+	esr = read_sysreg(esr_el1);
+	ec = (esr >> ESR_EC_SHIFT) & ESR_EC_MASK;
+
+	__GUEST_ASSERT(expected_ec == ec,
+			"PC: 0x%lx; ESR: 0x%lx; EC: 0x%lx; EC expected: 0x%lx",
+			regs->pc, esr, ec, expected_ec);
+
+	/* skip the trapping instruction */
+	regs->pc += 4;
+
+	/* Use INVALID_EC to indicate an exception occurred */
+	expected_ec = INVALID_EC;
+}
+
+/*
+ * Run the given operation that should trigger an exception with the
+ * given exception class. The exception handler (guest_sync_handler)
+ * will reset op_end_addr to 0, expected_ec to INVALID_EC, and skip
+ * the instruction that trapped.
+ */
+#define TEST_EXCEPTION(ec, ops)				\
+({							\
+	GUEST_ASSERT(ec != INVALID_EC);			\
+	WRITE_ONCE(expected_ec, ec);			\
+	dsb(ish);					\
+	ops;						\
+	GUEST_ASSERT(expected_ec == INVALID_EC);	\
+})
+
+/*
+ * Tests for reading/writing registers for the unimplemented event counter
+ * specified by @pmc_idx (>= PMCR_EL0.N).
+ */
+static void test_access_invalid_pmc_regs(struct pmc_accessor *acc, int pmc_idx)
+{
+	/*
+	 * Reading/writing the event count/type registers should cause
+	 * an UNDEFINED exception.
+	 */
+	TEST_EXCEPTION(ESR_EC_UNKNOWN, acc->read_cntr(pmc_idx));
+	TEST_EXCEPTION(ESR_EC_UNKNOWN, acc->write_cntr(pmc_idx, 0));
+	TEST_EXCEPTION(ESR_EC_UNKNOWN, acc->read_typer(pmc_idx));
+	TEST_EXCEPTION(ESR_EC_UNKNOWN, acc->write_typer(pmc_idx, 0));
+	/*
+	 * The bit corresponding to the (unimplemented) counter in
+	 * {PMCNTEN,PMINTEN,PMOVS}{SET,CLR} registers should be RAZ.
+	 */
+	test_bitmap_pmu_regs(pmc_idx, 1);
+	test_bitmap_pmu_regs(pmc_idx, 0);
+}
+
+/*
+ * The guest is configured with PMUv3 with @expected_pmcr_n number of
+ * event counters.
+ * Check if @expected_pmcr_n is consistent with PMCR_EL0.N, and
+ * if reading/writing PMU registers for implemented or unimplemented
+ * counters works as expected.
+ */
+static void guest_code(uint64_t expected_pmcr_n)
+{
+	uint64_t pmcr, pmcr_n, unimp_mask;
+	int i, pmc;
+
+	__GUEST_ASSERT(expected_pmcr_n <= ARMV8_PMU_MAX_GENERAL_COUNTERS,
+			"Expected PMCR.N: 0x%lx; ARMv8 general counters: 0x%lx",
+			expected_pmcr_n, ARMV8_PMU_MAX_GENERAL_COUNTERS);
+
+	pmcr = read_sysreg(pmcr_el0);
+	pmcr_n = get_pmcr_n(pmcr);
+
+	/* Make sure that PMCR_EL0.N indicates the value userspace set */
+	__GUEST_ASSERT(pmcr_n == expected_pmcr_n,
+			"Expected PMCR.N: 0x%lx, PMCR.N: 0x%lx",
+			expected_pmcr_n, pmcr_n);
+
+	/*
+	 * Make sure that (RAZ) bits corresponding to unimplemented event
+	 * counters in {PMCNTEN,PMINTEN,PMOVS}{SET,CLR} registers are reset
+	 * to zero.
+	 * (NOTE: bits for implemented event counters are reset to UNKNOWN)
+	 */
+	unimp_mask = GENMASK_ULL(ARMV8_PMU_MAX_GENERAL_COUNTERS - 1, pmcr_n);
+	check_bitmap_pmu_regs(unimp_mask, false);
+
+	/*
+	 * Tests for reading/writing PMU registers for implemented counters.
+	 * Use each combination of PMEV{CNTR,TYPER}<n>_EL0 accessor functions.
+	 */
+	for (i = 0; i < ARRAY_SIZE(pmc_accessors); i++) {
+		for (pmc = 0; pmc < pmcr_n; pmc++)
+			test_access_pmc_regs(&pmc_accessors[i], pmc);
+	}
+
+	/*
+	 * Tests for reading/writing PMU registers for unimplemented counters.
+	 * Use each combination of PMEV{CNTR,TYPER}<n>_EL0 accessor functions.
+	 */
+	for (i = 0; i < ARRAY_SIZE(pmc_accessors); i++) {
+		for (pmc = pmcr_n; pmc < ARMV8_PMU_MAX_GENERAL_COUNTERS; pmc++)
+			test_access_invalid_pmc_regs(&pmc_accessors[i], pmc);
+	}
+
+	GUEST_DONE();
+}
+
+#define GICD_BASE_GPA	0x8000000ULL
+#define GICR_BASE_GPA	0x80A0000ULL
+
+/* Create a VM that has one vCPU with PMUv3 configured. */
+static void create_vpmu_vm(void *guest_code)
+{
+	struct kvm_vcpu_init init;
+	uint8_t pmuver, ec;
+	uint64_t dfr0, irq = 23;
+	struct kvm_device_attr irq_attr = {
+		.group = KVM_ARM_VCPU_PMU_V3_CTRL,
+		.attr = KVM_ARM_VCPU_PMU_V3_IRQ,
+		.addr = (uint64_t)&irq,
+	};
+	struct kvm_device_attr init_attr = {
+		.group = KVM_ARM_VCPU_PMU_V3_CTRL,
+		.attr = KVM_ARM_VCPU_PMU_V3_INIT,
+	};
+
+	/* The test creates the vpmu_vm multiple times. Ensure a clean state */
+	memset(&vpmu_vm, 0, sizeof(vpmu_vm));
+
+	vpmu_vm.vm = vm_create(1);
+	vm_init_descriptor_tables(vpmu_vm.vm);
+	for (ec = 0; ec < ESR_EC_NUM; ec++) {
+		vm_install_sync_handler(vpmu_vm.vm, VECTOR_SYNC_CURRENT, ec,
+					guest_sync_handler);
+	}
+
+	/* Create vCPU with PMUv3 */
+	vm_ioctl(vpmu_vm.vm, KVM_ARM_PREFERRED_TARGET, &init);
+	init.features[0] |= (1 << KVM_ARM_VCPU_PMU_V3);
+	vpmu_vm.vcpu = aarch64_vcpu_add(vpmu_vm.vm, 0, &init, guest_code);
+	vcpu_init_descriptor_tables(vpmu_vm.vcpu);
+	vpmu_vm.gic_fd = vgic_v3_setup(vpmu_vm.vm, 1, 64,
+					GICD_BASE_GPA, GICR_BASE_GPA);
+	__TEST_REQUIRE(vpmu_vm.gic_fd >= 0,
+		       "Failed to create vgic-v3, skipping");
+
+	/* Make sure that PMUv3 support is indicated in the ID register */
+	vcpu_get_reg(vpmu_vm.vcpu,
+		     KVM_ARM64_SYS_REG(SYS_ID_AA64DFR0_EL1), &dfr0);
+	pmuver = FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer), dfr0);
+	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);
+
+	/* Initialize vPMU */
+	vcpu_ioctl(vpmu_vm.vcpu, KVM_SET_DEVICE_ATTR, &irq_attr);
+	vcpu_ioctl(vpmu_vm.vcpu, KVM_SET_DEVICE_ATTR, &init_attr);
+}
+
+static void destroy_vpmu_vm(void)
+{
+	close(vpmu_vm.gic_fd);
+	kvm_vm_free(vpmu_vm.vm);
+}
+
+static void run_vcpu(struct kvm_vcpu *vcpu, uint64_t pmcr_n)
+{
+	struct ucall uc;
+
+	vcpu_args_set(vcpu, 1, pmcr_n);
+	vcpu_run(vcpu);
+	switch (get_ucall(vcpu, &uc)) {
+	case UCALL_ABORT:
+		REPORT_GUEST_ASSERT(uc);
+		break;
+	case UCALL_DONE:
+		break;
+	default:
+		TEST_FAIL("Unknown ucall %lu", uc.cmd);
+		break;
+	}
+}
+
+static void test_create_vpmu_vm_with_pmcr_n(uint64_t pmcr_n, bool expect_fail)
+{
+	struct kvm_vcpu *vcpu;
+	uint64_t pmcr, pmcr_orig;
+
+	create_vpmu_vm(guest_code);
+	vcpu = vpmu_vm.vcpu;
+
+	vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(SYS_PMCR_EL0), &pmcr_orig);
+	pmcr = pmcr_orig;
+
+	/*
+	 * Setting a larger value of PMCR.N should not modify the field, and
+	 * return a success.
+	 */
+	set_pmcr_n(&pmcr, pmcr_n);
+	vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_PMCR_EL0), pmcr);
+	vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(SYS_PMCR_EL0), &pmcr);
+
+	if (expect_fail)
+		TEST_ASSERT(pmcr_orig == pmcr,
+			    "PMCR.N modified by KVM to a larger value (PMCR: 0x%lx) for pmcr_n: 0x%lx\n",
+			    pmcr, pmcr_n);
+	else
+		TEST_ASSERT(pmcr_n == get_pmcr_n(pmcr),
+			    "Failed to update PMCR.N to %lu (received: %lu)\n",
+			    pmcr_n, get_pmcr_n(pmcr));
+}
+
+/*
+ * 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(uint64_t pmcr_n)
+{
+	uint64_t sp;
+	struct kvm_vcpu *vcpu;
+	struct kvm_vcpu_init init;
+
+	pr_debug("Test with pmcr_n %lu\n", pmcr_n);
+
+	test_create_vpmu_vm_with_pmcr_n(pmcr_n, false);
+	vcpu = vpmu_vm.vcpu;
+
+	/* Save the initial sp to restore them later to run the guest again */
+	vcpu_get_reg(vcpu, ARM64_CORE_REG(sp_el1), &sp);
+
+	run_vcpu(vcpu, pmcr_n);
+
+	/*
+	 * Reset and re-initialize the vCPU, and run the guest code again to
+	 * check if PMCR_EL0.N is preserved.
+	 */
+	vm_ioctl(vpmu_vm.vm, KVM_ARM_PREFERRED_TARGET, &init);
+	init.features[0] |= (1 << KVM_ARM_VCPU_PMU_V3);
+	aarch64_vcpu_setup(vcpu, &init);
+	vcpu_init_descriptor_tables(vcpu);
+	vcpu_set_reg(vcpu, ARM64_CORE_REG(sp_el1), sp);
+	vcpu_set_reg(vcpu, ARM64_CORE_REG(regs.pc), (uint64_t)guest_code);
+
+	run_vcpu(vcpu, pmcr_n);
+
+	destroy_vpmu_vm();
+}
+
+static struct pmreg_sets validity_check_reg_sets[] = {
+	PMREG_SET(SYS_PMCNTENSET_EL0, SYS_PMCNTENCLR_EL0),
+	PMREG_SET(SYS_PMINTENSET_EL1, SYS_PMINTENCLR_EL1),
+	PMREG_SET(SYS_PMOVSSET_EL0, SYS_PMOVSCLR_EL0),
+};
+
+/*
+ * 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(uint64_t pmcr_n)
+{
+	int i;
+	struct kvm_vcpu *vcpu;
+	uint64_t set_reg_id, clr_reg_id, reg_val;
+	uint64_t valid_counters_mask, max_counters_mask;
+
+	test_create_vpmu_vm_with_pmcr_n(pmcr_n, false);
+	vcpu = vpmu_vm.vcpu;
+
+	valid_counters_mask = get_counters_mask(pmcr_n);
+	max_counters_mask = get_counters_mask(ARMV8_PMU_MAX_COUNTERS);
+
+	for (i = 0; i < ARRAY_SIZE(validity_check_reg_sets); i++) {
+		set_reg_id = validity_check_reg_sets[i].set_reg_id;
+		clr_reg_id = validity_check_reg_sets[i].clr_reg_id;
+
+		/*
+		 * Test if the 'set' and 'clr' variants of the registers
+		 * are initialized based on the number of valid counters.
+		 */
+		vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(set_reg_id), &reg_val);
+		TEST_ASSERT((reg_val & (~valid_counters_mask)) == 0,
+			    "Initial read of set_reg: 0x%llx has unimplemented counters enabled: 0x%lx\n",
+			    KVM_ARM64_SYS_REG(set_reg_id), reg_val);
+
+		vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(clr_reg_id), &reg_val);
+		TEST_ASSERT((reg_val & (~valid_counters_mask)) == 0,
+			    "Initial read of clr_reg: 0x%llx has unimplemented counters enabled: 0x%lx\n",
+			    KVM_ARM64_SYS_REG(clr_reg_id), reg_val);
+
+		/*
+		 * Using the 'set' variant, force-set the register to the
+		 * max number of possible counters and test if KVM discards
+		 * the bits for unimplemented counters as it should.
+		 */
+		vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(set_reg_id), max_counters_mask);
+
+		vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(set_reg_id), &reg_val);
+		TEST_ASSERT((reg_val & (~valid_counters_mask)) == 0,
+			    "Read of set_reg: 0x%llx has unimplemented counters enabled: 0x%lx\n",
+			    KVM_ARM64_SYS_REG(set_reg_id), reg_val);
+
+		vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(clr_reg_id), &reg_val);
+		TEST_ASSERT((reg_val & (~valid_counters_mask)) == 0,
+			    "Read of clr_reg: 0x%llx has unimplemented counters enabled: 0x%lx\n",
+			    KVM_ARM64_SYS_REG(clr_reg_id), reg_val);
+	}
+
+	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.
+ * The attempt should fail as @pmcr_n is too big to set for the vCPU.
+ */
+static void run_error_test(uint64_t pmcr_n)
+{
+	pr_debug("Error test with pmcr_n %lu (larger than the host)\n", pmcr_n);
+
+	test_create_vpmu_vm_with_pmcr_n(pmcr_n, true);
+	destroy_vpmu_vm();
+}
+
+/*
+ * Return the default number of implemented PMU event counters excluding
+ * the cycle counter (i.e. PMCR_EL0.N value) for the guest.
+ */
+static uint64_t get_pmcr_n_limit(void)
+{
+	uint64_t pmcr;
+
+	create_vpmu_vm(guest_code);
+	vcpu_get_reg(vpmu_vm.vcpu, KVM_ARM64_SYS_REG(SYS_PMCR_EL0), &pmcr);
+	destroy_vpmu_vm();
+	return get_pmcr_n(pmcr);
+}
+
+int main(void)
+{
+	uint64_t i, pmcr_n;
+
+	TEST_REQUIRE(kvm_has_cap(KVM_CAP_ARM_PMU_V3));
+
+	pmcr_n = get_pmcr_n_limit();
+	for (i = 0; i <= pmcr_n; i++) {
+		run_access_test(i);
+		run_pmregs_validity_test(i);
+	}
+
+	for (i = pmcr_n + 1; i < ARMV8_PMU_MAX_COUNTERS; i++)
+		run_error_test(i);
+
+	return 0;
+}
diff --git a/tools/testing/selftests/kvm/include/aarch64/processor.h b/tools/testing/selftests/kvm/include/aarch64/processor.h
index cb537253a6b9..c42d683102c7 100644
--- a/tools/testing/selftests/kvm/include/aarch64/processor.h
+++ b/tools/testing/selftests/kvm/include/aarch64/processor.h
@@ -104,6 +104,7 @@ enum {
 #define ESR_EC_SHIFT		26
 #define ESR_EC_MASK		(ESR_EC_NUM - 1)
 
+#define ESR_EC_UNKNOWN		0x0
 #define ESR_EC_SVC64		0x15
 #define ESR_EC_IABT		0x21
 #define ESR_EC_DABT		0x25