// 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 "svm_util.h"
#include "kselftest.h"

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

#define TSC_OFFSET_L2 ((u64)-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(u64 actual, u64 expected)
{
        u64 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)
{
        u64 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_svm_code(struct svm_test_data *svm)
{
        unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];

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

        generic_svm_setup(svm, l2_guest_code,
                          &l2_guest_stack[L2_GUEST_STACK_SIZE]);

        /* enable TSC scaling for L2 */
        wrmsr(MSR_AMD64_TSC_RATIO, L2_SCALE_FACTOR << 32);

        /* launch L2 */
        run_guest(svm->vmcb, svm->vmcb_gpa);
        GUEST_ASSERT(svm->vmcb->control.exit_code == SVM_EXIT_VMMCALL);

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

        GUEST_DONE();
}

static void l1_vmx_code(struct vmx_pages *vmx_pages)
{
        unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
        u32 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 l1_guest_code(void *data)
{
        if (this_cpu_has(X86_FEATURE_VMX))
                l1_vmx_code(data);
        else
                l1_svm_code(data);
}

int main(int argc, char *argv[])
{
        struct kvm_vcpu *vcpu;
        struct kvm_vm *vm;
        gva_t guest_gva = 0;

        u64 tsc_start, tsc_end;
        u64 tsc_khz;
        u64 l1_scale_factor;
        u64 l0_tsc_freq = 0;
        u64 l1_tsc_freq = 0;
        u64 l2_tsc_freq = 0;

        TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_VMX) ||
                     kvm_cpu_has(X86_FEATURE_SVM));
        TEST_REQUIRE(kvm_has_cap(KVM_CAP_TSC_CONTROL));
        TEST_REQUIRE(sys_clocksource_is_based_on_tsc());

        /*
         * 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_with_one_vcpu(&vcpu, l1_guest_code);

        if (kvm_cpu_has(X86_FEATURE_VMX))
                vcpu_alloc_vmx(vm, &guest_gva);
        else
                vcpu_alloc_svm(vm, &guest_gva);

        vcpu_args_set(vcpu, 1, guest_gva);

        tsc_khz = __vcpu_ioctl(vcpu, 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(vcpu, KVM_SET_TSC_KHZ, (void *) (tsc_khz / l1_scale_factor));

        for (;;) {
                struct ucall uc;

                vcpu_run(vcpu);
                TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);

                switch (get_ucall(vcpu, &uc)) {
                case UCALL_ABORT:
                        REPORT_GUEST_ASSERT(uc);
                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;
}