tools/testing/selftests/kvm/steal_time.c - third_party/kernel - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * steal/stolen time test
  *
  * Copyright (C) 2020, Red Hat, Inc.
  */
 #include <stdio.h>
 #include <time.h>
 #include <sched.h>
 #include <pthread.h>
 #include <linux/kernel.h>
 #include <asm/kvm.h>
 #ifdef __riscv
 #include "sbi.h"
 #else
 #include <asm/kvm_para.h>
 #endif

 #include "test_util.h"
 #include "kvm_util.h"
 #include "processor.h"
 #include "ucall_common.h"

 #define NR_VCPUS		4
 #define ST_GPA_BASE		(1 << 30)

 static void *st_gva[NR_VCPUS];
 static uint64_t guest_stolen_time[NR_VCPUS];

 #if defined(__x86_64__)

 /* steal_time must have 64-byte alignment */
 #define STEAL_TIME_SIZE		((sizeof(struct kvm_steal_time) + 63) & ~63)

 static void check_status(struct kvm_steal_time *st)
 {
 	GUEST_ASSERT(!(READ_ONCE(st->version) & 1));
 	GUEST_ASSERT_EQ(READ_ONCE(st->flags), 0);
 	GUEST_ASSERT_EQ(READ_ONCE(st->preempted), 0);
 }

 static void guest_code(int cpu)
 {
 	struct kvm_steal_time *st = st_gva[cpu];
 	uint32_t version;

 	GUEST_ASSERT_EQ(rdmsr(MSR_KVM_STEAL_TIME), ((uint64_t)st_gva[cpu] | KVM_MSR_ENABLED));

 	memset(st, 0, sizeof(*st));
 	GUEST_SYNC(0);

 	check_status(st);
 	WRITE_ONCE(guest_stolen_time[cpu], st->steal);
 	version = READ_ONCE(st->version);
 	check_status(st);
 	GUEST_SYNC(1);

 	check_status(st);
 	GUEST_ASSERT(version < READ_ONCE(st->version));
 	WRITE_ONCE(guest_stolen_time[cpu], st->steal);
 	check_status(st);
 	GUEST_DONE();
 }

 static bool is_steal_time_supported(struct kvm_vcpu *vcpu)
 {
 	return kvm_cpu_has(X86_FEATURE_KVM_STEAL_TIME);
 }

 static void steal_time_init(struct kvm_vcpu *vcpu, uint32_t i)
 {
 	int ret;

 	/* ST_GPA_BASE is identity mapped */
 	st_gva[i] = (void *)(ST_GPA_BASE + i * STEAL_TIME_SIZE);
 	sync_global_to_guest(vcpu->vm, st_gva[i]);

 	ret = _vcpu_set_msr(vcpu, MSR_KVM_STEAL_TIME,
 			    (ulong)st_gva[i] | KVM_STEAL_RESERVED_MASK);
 	TEST_ASSERT(ret == 0, "Bad GPA didn't fail");

 	vcpu_set_msr(vcpu, MSR_KVM_STEAL_TIME, (ulong)st_gva[i] | KVM_MSR_ENABLED);
 }

 static void steal_time_dump(struct kvm_vm *vm, uint32_t vcpu_idx)
 {
 	struct kvm_steal_time *st = addr_gva2hva(vm, (ulong)st_gva[vcpu_idx]);

 	ksft_print_msg("VCPU%d:\n", vcpu_idx);
 	ksft_print_msg("    steal:     %lld\n", st->steal);
 	ksft_print_msg("    version:   %d\n", st->version);
 	ksft_print_msg("    flags:     %d\n", st->flags);
 	ksft_print_msg("    preempted: %d\n", st->preempted);
 	ksft_print_msg("    u8_pad:    %d %d %d\n",
 			st->u8_pad[0], st->u8_pad[1], st->u8_pad[2]);
 	ksft_print_msg("    pad:       %d %d %d %d %d %d %d %d %d %d %d\n",
 			st->pad[0], st->pad[1], st->pad[2], st->pad[3],
 			st->pad[4], st->pad[5], st->pad[6], st->pad[7],
 			st->pad[8], st->pad[9], st->pad[10]);
 }

 #elif defined(__aarch64__)

 /* PV_TIME_ST must have 64-byte alignment */
 #define STEAL_TIME_SIZE		((sizeof(struct st_time) + 63) & ~63)

 #define SMCCC_ARCH_FEATURES	0x80000001
 #define PV_TIME_FEATURES	0xc5000020
 #define PV_TIME_ST		0xc5000021

 struct st_time {
 	uint32_t rev;
 	uint32_t attr;
 	uint64_t st_time;
 };

 static int64_t smccc(uint32_t func, uint64_t arg)
 {
 	struct arm_smccc_res res;

 	smccc_hvc(func, arg, 0, 0, 0, 0, 0, 0, &res);
 	return res.a0;
 }

 static void check_status(struct st_time *st)
 {
 	GUEST_ASSERT_EQ(READ_ONCE(st->rev), 0);
 	GUEST_ASSERT_EQ(READ_ONCE(st->attr), 0);
 }

 static void guest_code(int cpu)
 {
 	struct st_time *st;
 	int64_t status;

 	status = smccc(SMCCC_ARCH_FEATURES, PV_TIME_FEATURES);
 	GUEST_ASSERT_EQ(status, 0);
 	status = smccc(PV_TIME_FEATURES, PV_TIME_FEATURES);
 	GUEST_ASSERT_EQ(status, 0);
 	status = smccc(PV_TIME_FEATURES, PV_TIME_ST);
 	GUEST_ASSERT_EQ(status, 0);

 	status = smccc(PV_TIME_ST, 0);
 	GUEST_ASSERT_NE(status, -1);
 	GUEST_ASSERT_EQ(status, (ulong)st_gva[cpu]);

 	st = (struct st_time *)status;
 	GUEST_SYNC(0);

 	check_status(st);
 	WRITE_ONCE(guest_stolen_time[cpu], st->st_time);
 	GUEST_SYNC(1);

 	check_status(st);
 	WRITE_ONCE(guest_stolen_time[cpu], st->st_time);
 	GUEST_DONE();
 }

 static bool is_steal_time_supported(struct kvm_vcpu *vcpu)
 {
 	struct kvm_device_attr dev = {
 		.group = KVM_ARM_VCPU_PVTIME_CTRL,
 		.attr = KVM_ARM_VCPU_PVTIME_IPA,
 	};

 	return !__vcpu_ioctl(vcpu, KVM_HAS_DEVICE_ATTR, &dev);
 }

 static void steal_time_init(struct kvm_vcpu *vcpu, uint32_t i)
 {
 	struct kvm_vm *vm = vcpu->vm;
 	uint64_t st_ipa;
 	int ret;

 	struct kvm_device_attr dev = {
 		.group = KVM_ARM_VCPU_PVTIME_CTRL,
 		.attr = KVM_ARM_VCPU_PVTIME_IPA,
 		.addr = (uint64_t)&st_ipa,
 	};

 	vcpu_ioctl(vcpu, KVM_HAS_DEVICE_ATTR, &dev);

 	/* ST_GPA_BASE is identity mapped */
 	st_gva[i] = (void *)(ST_GPA_BASE + i * STEAL_TIME_SIZE);
 	sync_global_to_guest(vm, st_gva[i]);

 	st_ipa = (ulong)st_gva[i] | 1;
 	ret = __vcpu_ioctl(vcpu, KVM_SET_DEVICE_ATTR, &dev);
 	TEST_ASSERT(ret == -1 && errno == EINVAL, "Bad IPA didn't report EINVAL");

 	st_ipa = (ulong)st_gva[i];
 	vcpu_ioctl(vcpu, KVM_SET_DEVICE_ATTR, &dev);

 	ret = __vcpu_ioctl(vcpu, KVM_SET_DEVICE_ATTR, &dev);
 	TEST_ASSERT(ret == -1 && errno == EEXIST, "Set IPA twice without EEXIST");
 }

 static void steal_time_dump(struct kvm_vm *vm, uint32_t vcpu_idx)
 {
 	struct st_time *st = addr_gva2hva(vm, (ulong)st_gva[vcpu_idx]);

 	ksft_print_msg("VCPU%d:\n", vcpu_idx);
 	ksft_print_msg("    rev:     %d\n", st->rev);
 	ksft_print_msg("    attr:    %d\n", st->attr);
 	ksft_print_msg("    st_time: %ld\n", st->st_time);
 }

 #elif defined(__riscv)

 /* SBI STA shmem must have 64-byte alignment */
 #define STEAL_TIME_SIZE		((sizeof(struct sta_struct) + 63) & ~63)

 static vm_paddr_t st_gpa[NR_VCPUS];

 struct sta_struct {
 	uint32_t sequence;
 	uint32_t flags;
 	uint64_t steal;
 	uint8_t preempted;
 	uint8_t pad[47];
 } __packed;

 static void sta_set_shmem(vm_paddr_t gpa, unsigned long flags)
 {
 	unsigned long lo = (unsigned long)gpa;
 #if __riscv_xlen == 32
 	unsigned long hi = (unsigned long)(gpa >> 32);
 #else
 	unsigned long hi = gpa == -1 ? -1 : 0;
 #endif
 	struct sbiret ret = sbi_ecall(SBI_EXT_STA, 0, lo, hi, flags, 0, 0, 0);

 	GUEST_ASSERT(ret.value == 0 && ret.error == 0);
 }

 static void check_status(struct sta_struct *st)
 {
 	GUEST_ASSERT(!(READ_ONCE(st->sequence) & 1));
 	GUEST_ASSERT(READ_ONCE(st->flags) == 0);
 	GUEST_ASSERT(READ_ONCE(st->preempted) == 0);
 }

 static void guest_code(int cpu)
 {
 	struct sta_struct *st = st_gva[cpu];
 	uint32_t sequence;
 	long out_val = 0;
 	bool probe;

 	probe = guest_sbi_probe_extension(SBI_EXT_STA, &out_val);
 	GUEST_ASSERT(probe && out_val == 1);

 	sta_set_shmem(st_gpa[cpu], 0);
 	GUEST_SYNC(0);

 	check_status(st);
 	WRITE_ONCE(guest_stolen_time[cpu], st->steal);
 	sequence = READ_ONCE(st->sequence);
 	check_status(st);
 	GUEST_SYNC(1);

 	check_status(st);
 	GUEST_ASSERT(sequence < READ_ONCE(st->sequence));
 	WRITE_ONCE(guest_stolen_time[cpu], st->steal);
 	check_status(st);
 	GUEST_DONE();
 }

 static bool is_steal_time_supported(struct kvm_vcpu *vcpu)
 {
 	uint64_t id = RISCV_SBI_EXT_REG(KVM_RISCV_SBI_EXT_STA);
 	unsigned long enabled;

 	vcpu_get_reg(vcpu, id, &enabled);
 	TEST_ASSERT(enabled == 0 || enabled == 1, "Expected boolean result");

 	return enabled;
 }

 static void steal_time_init(struct kvm_vcpu *vcpu, uint32_t i)
 {
 	/* ST_GPA_BASE is identity mapped */
 	st_gva[i] = (void *)(ST_GPA_BASE + i * STEAL_TIME_SIZE);
 	st_gpa[i] = addr_gva2gpa(vcpu->vm, (vm_vaddr_t)st_gva[i]);
 	sync_global_to_guest(vcpu->vm, st_gva[i]);
 	sync_global_to_guest(vcpu->vm, st_gpa[i]);
 }

 static void steal_time_dump(struct kvm_vm *vm, uint32_t vcpu_idx)
 {
 	struct sta_struct *st = addr_gva2hva(vm, (ulong)st_gva[vcpu_idx]);
 	int i;

 	pr_info("VCPU%d:\n", vcpu_idx);
 	pr_info("    sequence:  %d\n", st->sequence);
 	pr_info("    flags:     %d\n", st->flags);
 	pr_info("    steal:     %"PRIu64"\n", st->steal);
 	pr_info("    preempted: %d\n", st->preempted);
 	pr_info("    pad:      ");
 	for (i = 0; i < 47; ++i)
 		pr_info("%d", st->pad[i]);
 	pr_info("\n");
 }

 #endif

 static void *do_steal_time(void *arg)
 {
 	struct timespec ts, stop;

 	clock_gettime(CLOCK_MONOTONIC, &ts);
 	stop = timespec_add_ns(ts, MIN_RUN_DELAY_NS);

 	while (1) {
 		clock_gettime(CLOCK_MONOTONIC, &ts);
 		if (timespec_to_ns(timespec_sub(ts, stop)) >= 0)
 			break;
 	}

 	return NULL;
 }

 static void run_vcpu(struct kvm_vcpu *vcpu)
 {
 	struct ucall uc;

 	vcpu_run(vcpu);

 	switch (get_ucall(vcpu, &uc)) {
 	case UCALL_SYNC:
 	case UCALL_DONE:
 		break;
 	case UCALL_ABORT:
 		REPORT_GUEST_ASSERT(uc);
 	default:
 		TEST_ASSERT(false, "Unexpected exit: %s",
 			    exit_reason_str(vcpu->run->exit_reason));
 	}
 }

 int main(int ac, char **av)
 {
 	struct kvm_vcpu *vcpus[NR_VCPUS];
 	struct kvm_vm *vm;
 	pthread_attr_t attr;
 	pthread_t thread;
 	cpu_set_t cpuset;
 	unsigned int gpages;
 	long stolen_time;
 	long run_delay;
 	bool verbose;
 	int i;

 	verbose = ac > 1 && (!strncmp(av[1], "-v", 3) || !strncmp(av[1], "--verbose", 10));

 	/* Set CPU affinity so we can force preemption of the VCPU */
 	CPU_ZERO(&cpuset);
 	CPU_SET(0, &cpuset);
 	pthread_attr_init(&attr);
 	pthread_attr_setaffinity_np(&attr, sizeof(cpu_set_t), &cpuset);
 	pthread_setaffinity_np(pthread_self(), sizeof(cpu_set_t), &cpuset);

 	/* Create a VM and an identity mapped memslot for the steal time structure */
 	vm = vm_create_with_vcpus(NR_VCPUS, guest_code, vcpus);
 	gpages = vm_calc_num_guest_pages(VM_MODE_DEFAULT, STEAL_TIME_SIZE * NR_VCPUS);
 	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, ST_GPA_BASE, 1, gpages, 0);
 	virt_map(vm, ST_GPA_BASE, ST_GPA_BASE, gpages);

 	ksft_print_header();
 	TEST_REQUIRE(is_steal_time_supported(vcpus[0]));
 	ksft_set_plan(NR_VCPUS);

 	/* Run test on each VCPU */
 	for (i = 0; i < NR_VCPUS; ++i) {
 		steal_time_init(vcpus[i], i);

 		vcpu_args_set(vcpus[i], 1, i);

 		/* First VCPU run initializes steal-time */
 		run_vcpu(vcpus[i]);

 		/* Second VCPU run, expect guest stolen time to be <= run_delay */
 		run_vcpu(vcpus[i]);
 		sync_global_from_guest(vm, guest_stolen_time[i]);
 		stolen_time = guest_stolen_time[i];
 		run_delay = get_run_delay();
 		TEST_ASSERT(stolen_time <= run_delay,
 			    "Expected stolen time <= %ld, got %ld",
 			    run_delay, stolen_time);

 		/* Steal time from the VCPU. The steal time thread has the same CPU affinity as the VCPUs. */
 		run_delay = get_run_delay();
 		pthread_create(&thread, &attr, do_steal_time, NULL);
 		do
 			sched_yield();
 		while (get_run_delay() - run_delay < MIN_RUN_DELAY_NS);
 		pthread_join(thread, NULL);
 		run_delay = get_run_delay() - run_delay;
 		TEST_ASSERT(run_delay >= MIN_RUN_DELAY_NS,
 			    "Expected run_delay >= %ld, got %ld",
 			    MIN_RUN_DELAY_NS, run_delay);

 		/* Run VCPU again to confirm stolen time is consistent with run_delay */
 		run_vcpu(vcpus[i]);
 		sync_global_from_guest(vm, guest_stolen_time[i]);
 		stolen_time = guest_stolen_time[i] - stolen_time;
 		TEST_ASSERT(stolen_time >= run_delay,
 			    "Expected stolen time >= %ld, got %ld",
 			    run_delay, stolen_time);

 		if (verbose) {
 			ksft_print_msg("VCPU%d: total-stolen-time=%ld test-stolen-time=%ld%s\n",
 				       i, guest_stolen_time[i], stolen_time,
 				       stolen_time == run_delay ?
 				       " (BONUS: guest test-stolen-time even exactly matches test-run_delay)" : "");
 			steal_time_dump(vm, i);
 		}
 		ksft_test_result_pass("vcpu%d\n", i);
 	}

 	/* Print results and exit() accordingly */
 	ksft_finished();
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* steal/stolen time test
	*
	* Copyright (C) 2020, Red Hat, Inc.
	*/
	#include <stdio.h>
	#include <time.h>
	#include <sched.h>
	#include <pthread.h>
	#include <linux/kernel.h>
	#include <asm/kvm.h>
	#ifdef __riscv
	#include "sbi.h"
	#else
	#include <asm/kvm_para.h>
	#endif

	#include "test_util.h"
	#include "kvm_util.h"
	#include "processor.h"
	#include "ucall_common.h"

	#define NR_VCPUS 4
	#define ST_GPA_BASE (1 << 30)

	static void *st_gva[NR_VCPUS];
	static uint64_t guest_stolen_time[NR_VCPUS];

	#if defined(__x86_64__)

	/* steal_time must have 64-byte alignment */
	#define STEAL_TIME_SIZE ((sizeof(struct kvm_steal_time) + 63) & ~63)

	static void check_status(struct kvm_steal_time *st)
	{
	GUEST_ASSERT(!(READ_ONCE(st->version) & 1));
	GUEST_ASSERT_EQ(READ_ONCE(st->flags), 0);
	GUEST_ASSERT_EQ(READ_ONCE(st->preempted), 0);
	}

	static void guest_code(int cpu)
	{
	struct kvm_steal_time *st = st_gva[cpu];
	uint32_t version;

	GUEST_ASSERT_EQ(rdmsr(MSR_KVM_STEAL_TIME), ((uint64_t)st_gva[cpu] \| KVM_MSR_ENABLED));

	memset(st, 0, sizeof(*st));
	GUEST_SYNC(0);

	check_status(st);
	WRITE_ONCE(guest_stolen_time[cpu], st->steal);
	version = READ_ONCE(st->version);
	check_status(st);
	GUEST_SYNC(1);

	check_status(st);
	GUEST_ASSERT(version < READ_ONCE(st->version));
	WRITE_ONCE(guest_stolen_time[cpu], st->steal);
	check_status(st);
	GUEST_DONE();
	}

	static bool is_steal_time_supported(struct kvm_vcpu *vcpu)
	{
	return kvm_cpu_has(X86_FEATURE_KVM_STEAL_TIME);
	}

	static void steal_time_init(struct kvm_vcpu *vcpu, uint32_t i)
	{
	int ret;

	/* ST_GPA_BASE is identity mapped */
	st_gva[i] = (void )(ST_GPA_BASE + i STEAL_TIME_SIZE);
	sync_global_to_guest(vcpu->vm, st_gva[i]);

	ret = _vcpu_set_msr(vcpu, MSR_KVM_STEAL_TIME,
	(ulong)st_gva[i] \| KVM_STEAL_RESERVED_MASK);
	TEST_ASSERT(ret == 0, "Bad GPA didn't fail");

	vcpu_set_msr(vcpu, MSR_KVM_STEAL_TIME, (ulong)st_gva[i] \| KVM_MSR_ENABLED);
	}

	static void steal_time_dump(struct kvm_vm *vm, uint32_t vcpu_idx)
	{
	struct kvm_steal_time *st = addr_gva2hva(vm, (ulong)st_gva[vcpu_idx]);

	ksft_print_msg("VCPU%d:\n", vcpu_idx);
	ksft_print_msg(" steal: %lld\n", st->steal);
	ksft_print_msg(" version: %d\n", st->version);
	ksft_print_msg(" flags: %d\n", st->flags);
	ksft_print_msg(" preempted: %d\n", st->preempted);
	ksft_print_msg(" u8_pad: %d %d %d\n",
	st->u8_pad[0], st->u8_pad[1], st->u8_pad[2]);
	ksft_print_msg(" pad: %d %d %d %d %d %d %d %d %d %d %d\n",
	st->pad[0], st->pad[1], st->pad[2], st->pad[3],
	st->pad[4], st->pad[5], st->pad[6], st->pad[7],
	st->pad[8], st->pad[9], st->pad[10]);
	}

	#elif defined(__aarch64__)

	/* PV_TIME_ST must have 64-byte alignment */
	#define STEAL_TIME_SIZE ((sizeof(struct st_time) + 63) & ~63)

	#define SMCCC_ARCH_FEATURES 0x80000001
	#define PV_TIME_FEATURES 0xc5000020
	#define PV_TIME_ST 0xc5000021

	struct st_time {
	uint32_t rev;
	uint32_t attr;
	uint64_t st_time;
	};

	static int64_t smccc(uint32_t func, uint64_t arg)
	{
	struct arm_smccc_res res;

	smccc_hvc(func, arg, 0, 0, 0, 0, 0, 0, &res);
	return res.a0;
	}

	static void check_status(struct st_time *st)
	{
	GUEST_ASSERT_EQ(READ_ONCE(st->rev), 0);
	GUEST_ASSERT_EQ(READ_ONCE(st->attr), 0);
	}

	static void guest_code(int cpu)
	{
	struct st_time *st;
	int64_t status;

	status = smccc(SMCCC_ARCH_FEATURES, PV_TIME_FEATURES);
	GUEST_ASSERT_EQ(status, 0);
	status = smccc(PV_TIME_FEATURES, PV_TIME_FEATURES);
	GUEST_ASSERT_EQ(status, 0);
	status = smccc(PV_TIME_FEATURES, PV_TIME_ST);
	GUEST_ASSERT_EQ(status, 0);

	status = smccc(PV_TIME_ST, 0);
	GUEST_ASSERT_NE(status, -1);
	GUEST_ASSERT_EQ(status, (ulong)st_gva[cpu]);

	st = (struct st_time *)status;
	GUEST_SYNC(0);

	check_status(st);
	WRITE_ONCE(guest_stolen_time[cpu], st->st_time);
	GUEST_SYNC(1);

	check_status(st);
	WRITE_ONCE(guest_stolen_time[cpu], st->st_time);
	GUEST_DONE();
	}

	static bool is_steal_time_supported(struct kvm_vcpu *vcpu)
	{
	struct kvm_device_attr dev = {
	.group = KVM_ARM_VCPU_PVTIME_CTRL,
	.attr = KVM_ARM_VCPU_PVTIME_IPA,
	};

	return !__vcpu_ioctl(vcpu, KVM_HAS_DEVICE_ATTR, &dev);
	}

	static void steal_time_init(struct kvm_vcpu *vcpu, uint32_t i)
	{
	struct kvm_vm *vm = vcpu->vm;
	uint64_t st_ipa;
	int ret;

	struct kvm_device_attr dev = {
	.group = KVM_ARM_VCPU_PVTIME_CTRL,
	.attr = KVM_ARM_VCPU_PVTIME_IPA,
	.addr = (uint64_t)&st_ipa,
	};

	vcpu_ioctl(vcpu, KVM_HAS_DEVICE_ATTR, &dev);

	/* ST_GPA_BASE is identity mapped */
	st_gva[i] = (void )(ST_GPA_BASE + i STEAL_TIME_SIZE);
	sync_global_to_guest(vm, st_gva[i]);

	st_ipa = (ulong)st_gva[i] \| 1;
	ret = __vcpu_ioctl(vcpu, KVM_SET_DEVICE_ATTR, &dev);
	TEST_ASSERT(ret == -1 && errno == EINVAL, "Bad IPA didn't report EINVAL");

	st_ipa = (ulong)st_gva[i];
	vcpu_ioctl(vcpu, KVM_SET_DEVICE_ATTR, &dev);

	ret = __vcpu_ioctl(vcpu, KVM_SET_DEVICE_ATTR, &dev);
	TEST_ASSERT(ret == -1 && errno == EEXIST, "Set IPA twice without EEXIST");
	}

	static void steal_time_dump(struct kvm_vm *vm, uint32_t vcpu_idx)
	{
	struct st_time *st = addr_gva2hva(vm, (ulong)st_gva[vcpu_idx]);

	ksft_print_msg("VCPU%d:\n", vcpu_idx);
	ksft_print_msg(" rev: %d\n", st->rev);
	ksft_print_msg(" attr: %d\n", st->attr);
	ksft_print_msg(" st_time: %ld\n", st->st_time);
	}

	#elif defined(__riscv)

	/* SBI STA shmem must have 64-byte alignment */
	#define STEAL_TIME_SIZE ((sizeof(struct sta_struct) + 63) & ~63)

	static vm_paddr_t st_gpa[NR_VCPUS];

	struct sta_struct {
	uint32_t sequence;
	uint32_t flags;
	uint64_t steal;
	uint8_t preempted;
	uint8_t pad[47];
	} __packed;

	static void sta_set_shmem(vm_paddr_t gpa, unsigned long flags)
	{
	unsigned long lo = (unsigned long)gpa;
	#if __riscv_xlen == 32
	unsigned long hi = (unsigned long)(gpa >> 32);
	#else
	unsigned long hi = gpa == -1 ? -1 : 0;
	#endif
	struct sbiret ret = sbi_ecall(SBI_EXT_STA, 0, lo, hi, flags, 0, 0, 0);

	GUEST_ASSERT(ret.value == 0 && ret.error == 0);
	}

	static void check_status(struct sta_struct *st)
	{
	GUEST_ASSERT(!(READ_ONCE(st->sequence) & 1));
	GUEST_ASSERT(READ_ONCE(st->flags) == 0);
	GUEST_ASSERT(READ_ONCE(st->preempted) == 0);
	}

	static void guest_code(int cpu)
	{
	struct sta_struct *st = st_gva[cpu];
	uint32_t sequence;
	long out_val = 0;
	bool probe;

	probe = guest_sbi_probe_extension(SBI_EXT_STA, &out_val);
	GUEST_ASSERT(probe && out_val == 1);

	sta_set_shmem(st_gpa[cpu], 0);
	GUEST_SYNC(0);

	check_status(st);
	WRITE_ONCE(guest_stolen_time[cpu], st->steal);
	sequence = READ_ONCE(st->sequence);
	check_status(st);
	GUEST_SYNC(1);

	check_status(st);
	GUEST_ASSERT(sequence < READ_ONCE(st->sequence));
	WRITE_ONCE(guest_stolen_time[cpu], st->steal);
	check_status(st);
	GUEST_DONE();
	}

	static bool is_steal_time_supported(struct kvm_vcpu *vcpu)
	{
	uint64_t id = RISCV_SBI_EXT_REG(KVM_RISCV_SBI_EXT_STA);
	unsigned long enabled;

	vcpu_get_reg(vcpu, id, &enabled);
	TEST_ASSERT(enabled == 0 \|\| enabled == 1, "Expected boolean result");

	return enabled;
	}

	static void steal_time_init(struct kvm_vcpu *vcpu, uint32_t i)
	{
	/* ST_GPA_BASE is identity mapped */
	st_gva[i] = (void )(ST_GPA_BASE + i STEAL_TIME_SIZE);
	st_gpa[i] = addr_gva2gpa(vcpu->vm, (vm_vaddr_t)st_gva[i]);
	sync_global_to_guest(vcpu->vm, st_gva[i]);
	sync_global_to_guest(vcpu->vm, st_gpa[i]);
	}

	static void steal_time_dump(struct kvm_vm *vm, uint32_t vcpu_idx)
	{
	struct sta_struct *st = addr_gva2hva(vm, (ulong)st_gva[vcpu_idx]);
	int i;

	pr_info("VCPU%d:\n", vcpu_idx);
	pr_info(" sequence: %d\n", st->sequence);
	pr_info(" flags: %d\n", st->flags);
	pr_info(" steal: %"PRIu64"\n", st->steal);
	pr_info(" preempted: %d\n", st->preempted);
	pr_info(" pad: ");
	for (i = 0; i < 47; ++i)
	pr_info("%d", st->pad[i]);
	pr_info("\n");
	}

	#endif

	static void do_steal_time(void arg)
	{
	struct timespec ts, stop;

	clock_gettime(CLOCK_MONOTONIC, &ts);
	stop = timespec_add_ns(ts, MIN_RUN_DELAY_NS);

	while (1) {
	clock_gettime(CLOCK_MONOTONIC, &ts);
	if (timespec_to_ns(timespec_sub(ts, stop)) >= 0)
	break;
	}

	return NULL;
	}

	static void run_vcpu(struct kvm_vcpu *vcpu)
	{
	struct ucall uc;

	vcpu_run(vcpu);

	switch (get_ucall(vcpu, &uc)) {
	case UCALL_SYNC:
	case UCALL_DONE:
	break;
	case UCALL_ABORT:
	REPORT_GUEST_ASSERT(uc);
	default:
	TEST_ASSERT(false, "Unexpected exit: %s",
	exit_reason_str(vcpu->run->exit_reason));
	}
	}

	int main(int ac, char **av)
	{
	struct kvm_vcpu *vcpus[NR_VCPUS];
	struct kvm_vm *vm;
	pthread_attr_t attr;
	pthread_t thread;
	cpu_set_t cpuset;
	unsigned int gpages;
	long stolen_time;
	long run_delay;
	bool verbose;
	int i;

	verbose = ac > 1 && (!strncmp(av[1], "-v", 3) \|\| !strncmp(av[1], "--verbose", 10));

	/* Set CPU affinity so we can force preemption of the VCPU */
	CPU_ZERO(&cpuset);
	CPU_SET(0, &cpuset);
	pthread_attr_init(&attr);
	pthread_attr_setaffinity_np(&attr, sizeof(cpu_set_t), &cpuset);
	pthread_setaffinity_np(pthread_self(), sizeof(cpu_set_t), &cpuset);

	/* Create a VM and an identity mapped memslot for the steal time structure */
	vm = vm_create_with_vcpus(NR_VCPUS, guest_code, vcpus);
	gpages = vm_calc_num_guest_pages(VM_MODE_DEFAULT, STEAL_TIME_SIZE * NR_VCPUS);
	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, ST_GPA_BASE, 1, gpages, 0);
	virt_map(vm, ST_GPA_BASE, ST_GPA_BASE, gpages);

	ksft_print_header();
	TEST_REQUIRE(is_steal_time_supported(vcpus[0]));
	ksft_set_plan(NR_VCPUS);

	/* Run test on each VCPU */
	for (i = 0; i < NR_VCPUS; ++i) {
	steal_time_init(vcpus[i], i);

	vcpu_args_set(vcpus[i], 1, i);

	/* First VCPU run initializes steal-time */
	run_vcpu(vcpus[i]);

	/* Second VCPU run, expect guest stolen time to be <= run_delay */
	run_vcpu(vcpus[i]);
	sync_global_from_guest(vm, guest_stolen_time[i]);
	stolen_time = guest_stolen_time[i];
	run_delay = get_run_delay();
	TEST_ASSERT(stolen_time <= run_delay,
	"Expected stolen time <= %ld, got %ld",
	run_delay, stolen_time);

	/* Steal time from the VCPU. The steal time thread has the same CPU affinity as the VCPUs. */
	run_delay = get_run_delay();
	pthread_create(&thread, &attr, do_steal_time, NULL);
	do
	sched_yield();
	while (get_run_delay() - run_delay < MIN_RUN_DELAY_NS);
	pthread_join(thread, NULL);
	run_delay = get_run_delay() - run_delay;
	TEST_ASSERT(run_delay >= MIN_RUN_DELAY_NS,
	"Expected run_delay >= %ld, got %ld",
	MIN_RUN_DELAY_NS, run_delay);

	/* Run VCPU again to confirm stolen time is consistent with run_delay */
	run_vcpu(vcpus[i]);
	sync_global_from_guest(vm, guest_stolen_time[i]);
	stolen_time = guest_stolen_time[i] - stolen_time;
	TEST_ASSERT(stolen_time >= run_delay,
	"Expected stolen time >= %ld, got %ld",
	run_delay, stolen_time);

	if (verbose) {
	ksft_print_msg("VCPU%d: total-stolen-time=%ld test-stolen-time=%ld%s\n",
	i, guest_stolen_time[i], stolen_time,
	stolen_time == run_delay ?
	" (BONUS: guest test-stolen-time even exactly matches test-run_delay)" : "");
	steal_time_dump(vm, i);
	}
	ksft_test_result_pass("vcpu%d\n", i);
	}

	/* Print results and exit() accordingly */
	ksft_finished();
	}