// SPDX-License-Identifier: GPL-2.0-only
/*
 * Test for KVM_X86_DISABLE_EXITS_APERFMPERF
 *
 * Copyright (C) 2025, Google LLC.
 *
 * Test the ability to disable VM-exits for rdmsr of IA32_APERF and
 * IA32_MPERF. When these VM-exits are disabled, reads of these MSRs
 * return the host's values.
 *
 * Note: Requires read access to /dev/cpu/<lpu>/msr to read host MSRs.
 */

#include <fcntl.h>
#include <limits.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdint.h>
#include <unistd.h>
#include <asm/msr-index.h>

#include "kvm_util.h"
#include "processor.h"
#include "svm_util.h"
#include "test_util.h"
#include "vmx.h"

#define NUM_ITERATIONS 10000

static int open_dev_msr(int cpu)
{
        char path[PATH_MAX];

        snprintf(path, sizeof(path), "/dev/cpu/%d/msr", cpu);
        return open_path_or_exit(path, O_RDONLY);
}

static uint64_t read_dev_msr(int msr_fd, uint32_t msr)
{
        uint64_t data;
        ssize_t rc;

        rc = pread(msr_fd, &data, sizeof(data), msr);
        TEST_ASSERT(rc == sizeof(data), "Read of MSR 0x%x failed", msr);

        return data;
}

static void guest_read_aperf_mperf(void)
{
        int i;

        for (i = 0; i < NUM_ITERATIONS; i++)
                GUEST_SYNC2(rdmsr(MSR_IA32_APERF), rdmsr(MSR_IA32_MPERF));
}

#define L2_GUEST_STACK_SIZE     64

static void l2_guest_code(void)
{
        guest_read_aperf_mperf();
        GUEST_DONE();
}

static void l1_svm_code(struct svm_test_data *svm)
{
        unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
        struct vmcb *vmcb = svm->vmcb;

        generic_svm_setup(svm, l2_guest_code, &l2_guest_stack[L2_GUEST_STACK_SIZE]);
        run_guest(vmcb, svm->vmcb_gpa);
}

static void l1_vmx_code(struct vmx_pages *vmx)
{
        unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];

        GUEST_ASSERT_EQ(prepare_for_vmx_operation(vmx), true);
        GUEST_ASSERT_EQ(load_vmcs(vmx), true);

        prepare_vmcs(vmx, NULL, &l2_guest_stack[L2_GUEST_STACK_SIZE]);

        /*
         * Enable MSR bitmaps (the bitmap itself is allocated, zeroed, and set
         * in the VMCS by prepare_vmcs()), as MSR exiting mandatory on Intel.
         */
        vmwrite(CPU_BASED_VM_EXEC_CONTROL,
                vmreadz(CPU_BASED_VM_EXEC_CONTROL) | CPU_BASED_USE_MSR_BITMAPS);

        GUEST_ASSERT(!vmwrite(GUEST_RIP, (u64)l2_guest_code));
        GUEST_ASSERT(!vmlaunch());
}

static void guest_code(void *nested_test_data)
{
        guest_read_aperf_mperf();

        if (this_cpu_has(X86_FEATURE_SVM))
                l1_svm_code(nested_test_data);
        else if (this_cpu_has(X86_FEATURE_VMX))
                l1_vmx_code(nested_test_data);
        else
                GUEST_DONE();

        TEST_FAIL("L2 should have signaled 'done'");
}

static void guest_no_aperfmperf(void)
{
        uint64_t msr_val;
        uint8_t vector;

        vector = rdmsr_safe(MSR_IA32_APERF, &msr_val);
        GUEST_ASSERT(vector == GP_VECTOR);

        vector = rdmsr_safe(MSR_IA32_APERF, &msr_val);
        GUEST_ASSERT(vector == GP_VECTOR);

        GUEST_DONE();
}

int main(int argc, char *argv[])
{
        const bool has_nested = kvm_cpu_has(X86_FEATURE_SVM) || kvm_cpu_has(X86_FEATURE_VMX);
        uint64_t host_aperf_before, host_mperf_before;
        vm_vaddr_t nested_test_data_gva;
        struct kvm_vcpu *vcpu;
        struct kvm_vm *vm;
        int msr_fd, cpu, i;

        /* Sanity check that APERF/MPERF are unsupported by default. */
        vm = vm_create_with_one_vcpu(&vcpu, guest_no_aperfmperf);
        vcpu_run(vcpu);
        TEST_ASSERT_EQ(get_ucall(vcpu, NULL), UCALL_DONE);
        kvm_vm_free(vm);

        cpu = pin_self_to_any_cpu();

        msr_fd = open_dev_msr(cpu);

        /*
         * This test requires a non-standard VM initialization, because
         * KVM_ENABLE_CAP cannot be used on a VM file descriptor after
         * a VCPU has been created.
         */
        vm = vm_create(1);

        TEST_REQUIRE(vm_check_cap(vm, KVM_CAP_X86_DISABLE_EXITS) &
                     KVM_X86_DISABLE_EXITS_APERFMPERF);

        vm_enable_cap(vm, KVM_CAP_X86_DISABLE_EXITS,
                      KVM_X86_DISABLE_EXITS_APERFMPERF);

        vcpu = vm_vcpu_add(vm, 0, guest_code);

        if (!has_nested)
                nested_test_data_gva = NONCANONICAL;
        else if (kvm_cpu_has(X86_FEATURE_SVM))
                vcpu_alloc_svm(vm, &nested_test_data_gva);
        else
                vcpu_alloc_vmx(vm, &nested_test_data_gva);

        vcpu_args_set(vcpu, 1, nested_test_data_gva);

        host_aperf_before = read_dev_msr(msr_fd, MSR_IA32_APERF);
        host_mperf_before = read_dev_msr(msr_fd, MSR_IA32_MPERF);

        for (i = 0; i <= NUM_ITERATIONS * (1 + has_nested); i++) {
                uint64_t host_aperf_after, host_mperf_after;
                uint64_t guest_aperf, guest_mperf;
                struct ucall uc;

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

                switch (get_ucall(vcpu, &uc)) {
                case UCALL_DONE:
                        goto done;
                case UCALL_ABORT:
                        REPORT_GUEST_ASSERT(uc);
                case UCALL_SYNC:
                        guest_aperf = uc.args[0];
                        guest_mperf = uc.args[1];

                        host_aperf_after = read_dev_msr(msr_fd, MSR_IA32_APERF);
                        host_mperf_after = read_dev_msr(msr_fd, MSR_IA32_MPERF);

                        TEST_ASSERT(host_aperf_before < guest_aperf,
                                    "APERF: host_before (0x%" PRIx64 ") >= guest (0x%" PRIx64 ")",
                                    host_aperf_before, guest_aperf);
                        TEST_ASSERT(guest_aperf < host_aperf_after,
                                    "APERF: guest (0x%" PRIx64 ") >= host_after (0x%" PRIx64 ")",
                                    guest_aperf, host_aperf_after);
                        TEST_ASSERT(host_mperf_before < guest_mperf,
                                    "MPERF: host_before (0x%" PRIx64 ") >= guest (0x%" PRIx64 ")",
                                    host_mperf_before, guest_mperf);
                        TEST_ASSERT(guest_mperf < host_mperf_after,
                                    "MPERF: guest (0x%" PRIx64 ") >= host_after (0x%" PRIx64 ")",
                                    guest_mperf, host_mperf_after);

                        host_aperf_before = host_aperf_after;
                        host_mperf_before = host_mperf_after;

                        break;
                }
        }
        TEST_FAIL("Didn't receive UCALL_DONE\n");
done:
        kvm_vm_free(vm);
        close(msr_fd);

        return 0;
}