tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * vmx_nested_tsc_scaling_test
  *
  * Copyright 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
  *
  * This test case verifies that nested TSC scaling behaves as expected when
  * both L1 and L2 are scaled using different ratios. For this test we scale
  * L1 down and scale L2 up.
  */

 #include <time.h>

 #include "kvm_util.h"
 #include "vmx.h"
 #include "kselftest.h"


 #define VCPU_ID 0

 /* L2 is scaled up (from L1's perspective) by this factor */
 #define L2_SCALE_FACTOR 4ULL

 #define TSC_OFFSET_L2 ((uint64_t) -33125236320908)
 #define TSC_MULTIPLIER_L2 (L2_SCALE_FACTOR << 48)

 #define L2_GUEST_STACK_SIZE 64

 enum { USLEEP, UCHECK_L1, UCHECK_L2 };
 #define GUEST_SLEEP(sec)         ucall(UCALL_SYNC, 2, USLEEP, sec)
 #define GUEST_CHECK(level, freq) ucall(UCALL_SYNC, 2, level, freq)


 /*
  * This function checks whether the "actual" TSC frequency of a guest matches
  * its expected frequency. In order to account for delays in taking the TSC
  * measurements, a difference of 1% between the actual and the expected value
  * is tolerated.
  */
 static void compare_tsc_freq(uint64_t actual, uint64_t expected)
 {
 	uint64_t tolerance, thresh_low, thresh_high;

 	tolerance = expected / 100;
 	thresh_low = expected - tolerance;
 	thresh_high = expected + tolerance;

 	TEST_ASSERT(thresh_low < actual,
 		"TSC freq is expected to be between %"PRIu64" and %"PRIu64
 		" but it actually is %"PRIu64,
 		thresh_low, thresh_high, actual);
 	TEST_ASSERT(thresh_high > actual,
 		"TSC freq is expected to be between %"PRIu64" and %"PRIu64
 		" but it actually is %"PRIu64,
 		thresh_low, thresh_high, actual);
 }

 static void check_tsc_freq(int level)
 {
 	uint64_t tsc_start, tsc_end, tsc_freq;

 	/*
 	 * Reading the TSC twice with about a second's difference should give
 	 * us an approximation of the TSC frequency from the guest's
 	 * perspective. Now, this won't be completely accurate, but it should
 	 * be good enough for the purposes of this test.
 	 */
 	tsc_start = rdmsr(MSR_IA32_TSC);
 	GUEST_SLEEP(1);
 	tsc_end = rdmsr(MSR_IA32_TSC);

 	tsc_freq = tsc_end - tsc_start;

 	GUEST_CHECK(level, tsc_freq);
 }

 static void l2_guest_code(void)
 {
 	check_tsc_freq(UCHECK_L2);

 	/* exit to L1 */
 	__asm__ __volatile__("vmcall");
 }

 static void l1_guest_code(struct vmx_pages *vmx_pages)
 {
 	unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
 	uint32_t control;

 	/* check that L1's frequency looks alright before launching L2 */
 	check_tsc_freq(UCHECK_L1);

 	GUEST_ASSERT(prepare_for_vmx_operation(vmx_pages));
 	GUEST_ASSERT(load_vmcs(vmx_pages));

 	/* prepare the VMCS for L2 execution */
 	prepare_vmcs(vmx_pages, l2_guest_code, &l2_guest_stack[L2_GUEST_STACK_SIZE]);

 	/* enable TSC offsetting and TSC scaling for L2 */
 	control = vmreadz(CPU_BASED_VM_EXEC_CONTROL);
 	control |= CPU_BASED_USE_MSR_BITMAPS | CPU_BASED_USE_TSC_OFFSETTING;
 	vmwrite(CPU_BASED_VM_EXEC_CONTROL, control);

 	control = vmreadz(SECONDARY_VM_EXEC_CONTROL);
 	control |= SECONDARY_EXEC_TSC_SCALING;
 	vmwrite(SECONDARY_VM_EXEC_CONTROL, control);

 	vmwrite(TSC_OFFSET, TSC_OFFSET_L2);
 	vmwrite(TSC_MULTIPLIER, TSC_MULTIPLIER_L2);
 	vmwrite(TSC_MULTIPLIER_HIGH, TSC_MULTIPLIER_L2 >> 32);

 	/* launch L2 */
 	GUEST_ASSERT(!vmlaunch());
 	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);

 	/* check that L1's frequency still looks good */
 	check_tsc_freq(UCHECK_L1);

 	GUEST_DONE();
 }

 static void tsc_scaling_check_supported(void)
 {
 	if (!kvm_check_cap(KVM_CAP_TSC_CONTROL)) {
 		print_skip("TSC scaling not supported by the HW");
 		exit(KSFT_SKIP);
 	}
 }

 static void stable_tsc_check_supported(void)
 {
 	FILE *fp;
 	char buf[4];

 	fp = fopen("/sys/devices/system/clocksource/clocksource0/current_clocksource", "r");
 	if (fp == NULL)
 		goto skip_test;

 	if (fgets(buf, sizeof(buf), fp) == NULL)
 		goto skip_test;

 	if (strncmp(buf, "tsc", sizeof(buf)))
 		goto skip_test;

 	return;
 skip_test:
 	print_skip("Kernel does not use TSC clocksource - assuming that host TSC is not stable");
 	exit(KSFT_SKIP);
 }

 int main(int argc, char *argv[])
 {
 	struct kvm_vm *vm;
 	vm_vaddr_t vmx_pages_gva;

 	uint64_t tsc_start, tsc_end;
 	uint64_t tsc_khz;
 	uint64_t l1_scale_factor;
 	uint64_t l0_tsc_freq = 0;
 	uint64_t l1_tsc_freq = 0;
 	uint64_t l2_tsc_freq = 0;

 	nested_vmx_check_supported();
 	tsc_scaling_check_supported();
 	stable_tsc_check_supported();

 	/*
 	 * We set L1's scale factor to be a random number from 2 to 10.
 	 * Ideally we would do the same for L2's factor but that one is
 	 * referenced by both main() and l1_guest_code() and using a global
 	 * variable does not work.
 	 */
 	srand(time(NULL));
 	l1_scale_factor = (rand() % 9) + 2;
 	printf("L1's scale down factor is: %"PRIu64"\n", l1_scale_factor);
 	printf("L2's scale up factor is: %llu\n", L2_SCALE_FACTOR);

 	tsc_start = rdtsc();
 	sleep(1);
 	tsc_end = rdtsc();

 	l0_tsc_freq = tsc_end - tsc_start;
 	printf("real TSC frequency is around: %"PRIu64"\n", l0_tsc_freq);

 	vm = vm_create_default(VCPU_ID, 0, (void *) l1_guest_code);
 	vcpu_alloc_vmx(vm, &vmx_pages_gva);
 	vcpu_args_set(vm, VCPU_ID, 1, vmx_pages_gva);

 	tsc_khz = _vcpu_ioctl(vm, VCPU_ID, KVM_GET_TSC_KHZ, NULL);
 	TEST_ASSERT(tsc_khz != -1, "vcpu ioctl KVM_GET_TSC_KHZ failed");

 	/* scale down L1's TSC frequency */
 	vcpu_ioctl(vm, VCPU_ID, KVM_SET_TSC_KHZ,
 		  (void *) (tsc_khz / l1_scale_factor));

 	for (;;) {
 		volatile struct kvm_run *run = vcpu_state(vm, VCPU_ID);
 		struct ucall uc;

 		vcpu_run(vm, VCPU_ID);
 		TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
 			    "Got exit_reason other than KVM_EXIT_IO: %u (%s)\n",
 			    run->exit_reason,
 			    exit_reason_str(run->exit_reason));

 		switch (get_ucall(vm, VCPU_ID, &uc)) {
 		case UCALL_ABORT:
 			TEST_FAIL("%s", (const char *) uc.args[0]);
 		case UCALL_SYNC:
 			switch (uc.args[0]) {
 			case USLEEP:
 				sleep(uc.args[1]);
 				break;
 			case UCHECK_L1:
 				l1_tsc_freq = uc.args[1];
 				printf("L1's TSC frequency is around: %"PRIu64
 				       "\n", l1_tsc_freq);

 				compare_tsc_freq(l1_tsc_freq,
 						 l0_tsc_freq / l1_scale_factor);
 				break;
 			case UCHECK_L2:
 				l2_tsc_freq = uc.args[1];
 				printf("L2's TSC frequency is around: %"PRIu64
 				       "\n", l2_tsc_freq);

 				compare_tsc_freq(l2_tsc_freq,
 						 l1_tsc_freq * L2_SCALE_FACTOR);
 				break;
 			}
 			break;
 		case UCALL_DONE:
 			goto done;
 		default:
 			TEST_FAIL("Unknown ucall %lu", uc.cmd);
 		}
 	}

 done:
 	kvm_vm_free(vm);
 	return 0;
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* vmx_nested_tsc_scaling_test
	*
	* Copyright 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
	*
	* This test case verifies that nested TSC scaling behaves as expected when
	* both L1 and L2 are scaled using different ratios. For this test we scale
	* L1 down and scale L2 up.
	*/

	#include <time.h>

	#include "kvm_util.h"
	#include "vmx.h"
	#include "kselftest.h"


	#define VCPU_ID 0

	/* L2 is scaled up (from L1's perspective) by this factor */
	#define L2_SCALE_FACTOR 4ULL

	#define TSC_OFFSET_L2 ((uint64_t) -33125236320908)
	#define TSC_MULTIPLIER_L2 (L2_SCALE_FACTOR << 48)

	#define L2_GUEST_STACK_SIZE 64

	enum { USLEEP, UCHECK_L1, UCHECK_L2 };
	#define GUEST_SLEEP(sec) ucall(UCALL_SYNC, 2, USLEEP, sec)
	#define GUEST_CHECK(level, freq) ucall(UCALL_SYNC, 2, level, freq)


	/*
	* This function checks whether the "actual" TSC frequency of a guest matches
	* its expected frequency. In order to account for delays in taking the TSC
	* measurements, a difference of 1% between the actual and the expected value
	* is tolerated.
	*/
	static void compare_tsc_freq(uint64_t actual, uint64_t expected)
	{
	uint64_t tolerance, thresh_low, thresh_high;

	tolerance = expected / 100;
	thresh_low = expected - tolerance;
	thresh_high = expected + tolerance;

	TEST_ASSERT(thresh_low < actual,
	"TSC freq is expected to be between %"PRIu64" and %"PRIu64
	" but it actually is %"PRIu64,
	thresh_low, thresh_high, actual);
	TEST_ASSERT(thresh_high > actual,
	"TSC freq is expected to be between %"PRIu64" and %"PRIu64
	" but it actually is %"PRIu64,
	thresh_low, thresh_high, actual);
	}

	static void check_tsc_freq(int level)
	{
	uint64_t tsc_start, tsc_end, tsc_freq;

	/*
	* Reading the TSC twice with about a second's difference should give
	* us an approximation of the TSC frequency from the guest's
	* perspective. Now, this won't be completely accurate, but it should
	* be good enough for the purposes of this test.
	*/
	tsc_start = rdmsr(MSR_IA32_TSC);
	GUEST_SLEEP(1);
	tsc_end = rdmsr(MSR_IA32_TSC);

	tsc_freq = tsc_end - tsc_start;

	GUEST_CHECK(level, tsc_freq);
	}

	static void l2_guest_code(void)
	{
	check_tsc_freq(UCHECK_L2);

	/* exit to L1 */
	__asm__ __volatile__("vmcall");
	}

	static void l1_guest_code(struct vmx_pages *vmx_pages)
	{
	unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
	uint32_t control;

	/* check that L1's frequency looks alright before launching L2 */
	check_tsc_freq(UCHECK_L1);

	GUEST_ASSERT(prepare_for_vmx_operation(vmx_pages));
	GUEST_ASSERT(load_vmcs(vmx_pages));

	/* prepare the VMCS for L2 execution */
	prepare_vmcs(vmx_pages, l2_guest_code, &l2_guest_stack[L2_GUEST_STACK_SIZE]);

	/* enable TSC offsetting and TSC scaling for L2 */
	control = vmreadz(CPU_BASED_VM_EXEC_CONTROL);
	control \|= CPU_BASED_USE_MSR_BITMAPS \| CPU_BASED_USE_TSC_OFFSETTING;
	vmwrite(CPU_BASED_VM_EXEC_CONTROL, control);

	control = vmreadz(SECONDARY_VM_EXEC_CONTROL);
	control \|= SECONDARY_EXEC_TSC_SCALING;
	vmwrite(SECONDARY_VM_EXEC_CONTROL, control);

	vmwrite(TSC_OFFSET, TSC_OFFSET_L2);
	vmwrite(TSC_MULTIPLIER, TSC_MULTIPLIER_L2);
	vmwrite(TSC_MULTIPLIER_HIGH, TSC_MULTIPLIER_L2 >> 32);

	/* launch L2 */
	GUEST_ASSERT(!vmlaunch());
	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);

	/* check that L1's frequency still looks good */
	check_tsc_freq(UCHECK_L1);

	GUEST_DONE();
	}

	static void tsc_scaling_check_supported(void)
	{
	if (!kvm_check_cap(KVM_CAP_TSC_CONTROL)) {
	print_skip("TSC scaling not supported by the HW");
	exit(KSFT_SKIP);
	}
	}

	static void stable_tsc_check_supported(void)
	{
	FILE *fp;
	char buf[4];

	fp = fopen("/sys/devices/system/clocksource/clocksource0/current_clocksource", "r");
	if (fp == NULL)
	goto skip_test;

	if (fgets(buf, sizeof(buf), fp) == NULL)
	goto skip_test;

	if (strncmp(buf, "tsc", sizeof(buf)))
	goto skip_test;

	return;
	skip_test:
	print_skip("Kernel does not use TSC clocksource - assuming that host TSC is not stable");
	exit(KSFT_SKIP);
	}

	int main(int argc, char *argv[])
	{
	struct kvm_vm *vm;
	vm_vaddr_t vmx_pages_gva;

	uint64_t tsc_start, tsc_end;
	uint64_t tsc_khz;
	uint64_t l1_scale_factor;
	uint64_t l0_tsc_freq = 0;
	uint64_t l1_tsc_freq = 0;
	uint64_t l2_tsc_freq = 0;

	nested_vmx_check_supported();
	tsc_scaling_check_supported();
	stable_tsc_check_supported();

	/*
	* We set L1's scale factor to be a random number from 2 to 10.
	* Ideally we would do the same for L2's factor but that one is
	* referenced by both main() and l1_guest_code() and using a global
	* variable does not work.
	*/
	srand(time(NULL));
	l1_scale_factor = (rand() % 9) + 2;
	printf("L1's scale down factor is: %"PRIu64"\n", l1_scale_factor);
	printf("L2's scale up factor is: %llu\n", L2_SCALE_FACTOR);

	tsc_start = rdtsc();
	sleep(1);
	tsc_end = rdtsc();

	l0_tsc_freq = tsc_end - tsc_start;
	printf("real TSC frequency is around: %"PRIu64"\n", l0_tsc_freq);

	vm = vm_create_default(VCPU_ID, 0, (void *) l1_guest_code);
	vcpu_alloc_vmx(vm, &vmx_pages_gva);
	vcpu_args_set(vm, VCPU_ID, 1, vmx_pages_gva);

	tsc_khz = _vcpu_ioctl(vm, VCPU_ID, KVM_GET_TSC_KHZ, NULL);
	TEST_ASSERT(tsc_khz != -1, "vcpu ioctl KVM_GET_TSC_KHZ failed");

	/* scale down L1's TSC frequency */
	vcpu_ioctl(vm, VCPU_ID, KVM_SET_TSC_KHZ,
	(void *) (tsc_khz / l1_scale_factor));

	for (;;) {
	volatile struct kvm_run *run = vcpu_state(vm, VCPU_ID);
	struct ucall uc;

	vcpu_run(vm, VCPU_ID);
	TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
	"Got exit_reason other than KVM_EXIT_IO: %u (%s)\n",
	run->exit_reason,
	exit_reason_str(run->exit_reason));

	switch (get_ucall(vm, VCPU_ID, &uc)) {
	case UCALL_ABORT:
	TEST_FAIL("%s", (const char *) uc.args[0]);
	case UCALL_SYNC:
	switch (uc.args[0]) {
	case USLEEP:
	sleep(uc.args[1]);
	break;
	case UCHECK_L1:
	l1_tsc_freq = uc.args[1];
	printf("L1's TSC frequency is around: %"PRIu64
	"\n", l1_tsc_freq);

	compare_tsc_freq(l1_tsc_freq,
	l0_tsc_freq / l1_scale_factor);
	break;
	case UCHECK_L2:
	l2_tsc_freq = uc.args[1];
	printf("L2's TSC frequency is around: %"PRIu64
	"\n", l2_tsc_freq);

	compare_tsc_freq(l2_tsc_freq,
	l1_tsc_freq * L2_SCALE_FACTOR);
	break;
	}
	break;
	case UCALL_DONE:
	goto done;
	default:
	TEST_FAIL("Unknown ucall %lu", uc.cmd);
	}
	}

	done:
	kvm_vm_free(vm);
	return 0;
	}