// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2020, Google LLC.
 *
 * Tests for exiting into userspace on registered MSRs
 */

#define _GNU_SOURCE /* for program_invocation_short_name */
#include <sys/ioctl.h>

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

/* Forced emulation prefix, used to invoke the emulator unconditionally. */
#define KVM_FEP "ud2; .byte 'k', 'v', 'm';"
#define KVM_FEP_LENGTH 5
static int fep_available = 1;

#define VCPU_ID       1
#define MSR_NON_EXISTENT 0x474f4f00

static u64 deny_bits = 0;
struct kvm_msr_filter filter_allow = {
        .flags = KVM_MSR_FILTER_DEFAULT_ALLOW,
        .ranges = {
                {
                        .flags = KVM_MSR_FILTER_READ |
                                 KVM_MSR_FILTER_WRITE,
                        .nmsrs = 1,
                        /* Test an MSR the kernel knows about. */
                        .base = MSR_IA32_XSS,
                        .bitmap = (uint8_t*)&deny_bits,
                }, {
                        .flags = KVM_MSR_FILTER_READ |
                                 KVM_MSR_FILTER_WRITE,
                        .nmsrs = 1,
                        /* Test an MSR the kernel doesn't know about. */
                        .base = MSR_IA32_FLUSH_CMD,
                        .bitmap = (uint8_t*)&deny_bits,
                }, {
                        .flags = KVM_MSR_FILTER_READ |
                                 KVM_MSR_FILTER_WRITE,
                        .nmsrs = 1,
                        /* Test a fabricated MSR that no one knows about. */
                        .base = MSR_NON_EXISTENT,
                        .bitmap = (uint8_t*)&deny_bits,
                },
        },
};

struct kvm_msr_filter filter_fs = {
        .flags = KVM_MSR_FILTER_DEFAULT_ALLOW,
        .ranges = {
                {
                        .flags = KVM_MSR_FILTER_READ,
                        .nmsrs = 1,
                        .base = MSR_FS_BASE,
                        .bitmap = (uint8_t*)&deny_bits,
                },
        },
};

struct kvm_msr_filter filter_gs = {
        .flags = KVM_MSR_FILTER_DEFAULT_ALLOW,
        .ranges = {
                {
                        .flags = KVM_MSR_FILTER_READ,
                        .nmsrs = 1,
                        .base = MSR_GS_BASE,
                        .bitmap = (uint8_t*)&deny_bits,
                },
        },
};

static uint64_t msr_non_existent_data;
static int guest_exception_count;
static u32 msr_reads, msr_writes;

static u8 bitmap_00000000[KVM_MSR_FILTER_MAX_BITMAP_SIZE];
static u8 bitmap_00000000_write[KVM_MSR_FILTER_MAX_BITMAP_SIZE];
static u8 bitmap_40000000[KVM_MSR_FILTER_MAX_BITMAP_SIZE];
static u8 bitmap_c0000000[KVM_MSR_FILTER_MAX_BITMAP_SIZE];
static u8 bitmap_c0000000_read[KVM_MSR_FILTER_MAX_BITMAP_SIZE];
static u8 bitmap_deadbeef[1] = { 0x1 };

static void deny_msr(uint8_t *bitmap, u32 msr)
{
        u32 idx = msr & (KVM_MSR_FILTER_MAX_BITMAP_SIZE - 1);

        bitmap[idx / 8] &= ~(1 << (idx % 8));
}

static void prepare_bitmaps(void)
{
        memset(bitmap_00000000, 0xff, sizeof(bitmap_00000000));
        memset(bitmap_00000000_write, 0xff, sizeof(bitmap_00000000_write));
        memset(bitmap_40000000, 0xff, sizeof(bitmap_40000000));
        memset(bitmap_c0000000, 0xff, sizeof(bitmap_c0000000));
        memset(bitmap_c0000000_read, 0xff, sizeof(bitmap_c0000000_read));

        deny_msr(bitmap_00000000_write, MSR_IA32_POWER_CTL);
        deny_msr(bitmap_c0000000_read, MSR_SYSCALL_MASK);
        deny_msr(bitmap_c0000000_read, MSR_GS_BASE);
}

struct kvm_msr_filter filter_deny = {
        .flags = KVM_MSR_FILTER_DEFAULT_DENY,
        .ranges = {
                {
                        .flags = KVM_MSR_FILTER_READ,
                        .base = 0x00000000,
                        .nmsrs = KVM_MSR_FILTER_MAX_BITMAP_SIZE * BITS_PER_BYTE,
                        .bitmap = bitmap_00000000,
                }, {
                        .flags = KVM_MSR_FILTER_WRITE,
                        .base = 0x00000000,
                        .nmsrs = KVM_MSR_FILTER_MAX_BITMAP_SIZE * BITS_PER_BYTE,
                        .bitmap = bitmap_00000000_write,
                }, {
                        .flags = KVM_MSR_FILTER_READ | KVM_MSR_FILTER_WRITE,
                        .base = 0x40000000,
                        .nmsrs = KVM_MSR_FILTER_MAX_BITMAP_SIZE * BITS_PER_BYTE,
                        .bitmap = bitmap_40000000,
                }, {
                        .flags = KVM_MSR_FILTER_READ,
                        .base = 0xc0000000,
                        .nmsrs = KVM_MSR_FILTER_MAX_BITMAP_SIZE * BITS_PER_BYTE,
                        .bitmap = bitmap_c0000000_read,
                }, {
                        .flags = KVM_MSR_FILTER_WRITE,
                        .base = 0xc0000000,
                        .nmsrs = KVM_MSR_FILTER_MAX_BITMAP_SIZE * BITS_PER_BYTE,
                        .bitmap = bitmap_c0000000,
                }, {
                        .flags = KVM_MSR_FILTER_WRITE | KVM_MSR_FILTER_READ,
                        .base = 0xdeadbeef,
                        .nmsrs = 1,
                        .bitmap = bitmap_deadbeef,
                },
        },
};

struct kvm_msr_filter no_filter_deny = {
        .flags = KVM_MSR_FILTER_DEFAULT_ALLOW,
};

/*
 * Note: Force test_rdmsr() to not be inlined to prevent the labels,
 * rdmsr_start and rdmsr_end, from being defined multiple times.
 */
static noinline uint64_t test_rdmsr(uint32_t msr)
{
        uint32_t a, d;

        guest_exception_count = 0;

        __asm__ __volatile__("rdmsr_start: rdmsr; rdmsr_end:" :
                        "=a"(a), "=d"(d) : "c"(msr) : "memory");

        return a | ((uint64_t) d << 32);
}

/*
 * Note: Force test_wrmsr() to not be inlined to prevent the labels,
 * wrmsr_start and wrmsr_end, from being defined multiple times.
 */
static noinline void test_wrmsr(uint32_t msr, uint64_t value)
{
        uint32_t a = value;
        uint32_t d = value >> 32;

        guest_exception_count = 0;

        __asm__ __volatile__("wrmsr_start: wrmsr; wrmsr_end:" ::
                        "a"(a), "d"(d), "c"(msr) : "memory");
}

extern char rdmsr_start, rdmsr_end;
extern char wrmsr_start, wrmsr_end;

/*
 * Note: Force test_em_rdmsr() to not be inlined to prevent the labels,
 * rdmsr_start and rdmsr_end, from being defined multiple times.
 */
static noinline uint64_t test_em_rdmsr(uint32_t msr)
{
        uint32_t a, d;

        guest_exception_count = 0;

        __asm__ __volatile__(KVM_FEP "em_rdmsr_start: rdmsr; em_rdmsr_end:" :
                        "=a"(a), "=d"(d) : "c"(msr) : "memory");

        return a | ((uint64_t) d << 32);
}

/*
 * Note: Force test_em_wrmsr() to not be inlined to prevent the labels,
 * wrmsr_start and wrmsr_end, from being defined multiple times.
 */
static noinline void test_em_wrmsr(uint32_t msr, uint64_t value)
{
        uint32_t a = value;
        uint32_t d = value >> 32;

        guest_exception_count = 0;

        __asm__ __volatile__(KVM_FEP "em_wrmsr_start: wrmsr; em_wrmsr_end:" ::
                        "a"(a), "d"(d), "c"(msr) : "memory");
}

extern char em_rdmsr_start, em_rdmsr_end;
extern char em_wrmsr_start, em_wrmsr_end;

static void guest_code_filter_allow(void)
{
        uint64_t data;

        /*
         * Test userspace intercepting rdmsr / wrmsr for MSR_IA32_XSS.
         *
         * A GP is thrown if anything other than 0 is written to
         * MSR_IA32_XSS.
         */
        data = test_rdmsr(MSR_IA32_XSS);
        GUEST_ASSERT(data == 0);
        GUEST_ASSERT(guest_exception_count == 0);

        test_wrmsr(MSR_IA32_XSS, 0);
        GUEST_ASSERT(guest_exception_count == 0);

        test_wrmsr(MSR_IA32_XSS, 1);
        GUEST_ASSERT(guest_exception_count == 1);

        /*
         * Test userspace intercepting rdmsr / wrmsr for MSR_IA32_FLUSH_CMD.
         *
         * A GP is thrown if MSR_IA32_FLUSH_CMD is read
         * from or if a value other than 1 is written to it.
         */
        test_rdmsr(MSR_IA32_FLUSH_CMD);
        GUEST_ASSERT(guest_exception_count == 1);

        test_wrmsr(MSR_IA32_FLUSH_CMD, 0);
        GUEST_ASSERT(guest_exception_count == 1);

        test_wrmsr(MSR_IA32_FLUSH_CMD, 1);
        GUEST_ASSERT(guest_exception_count == 0);

        /*
         * Test userspace intercepting rdmsr / wrmsr for MSR_NON_EXISTENT.
         *
         * Test that a fabricated MSR can pass through the kernel
         * and be handled in userspace.
         */
        test_wrmsr(MSR_NON_EXISTENT, 2);
        GUEST_ASSERT(guest_exception_count == 0);

        data = test_rdmsr(MSR_NON_EXISTENT);
        GUEST_ASSERT(data == 2);
        GUEST_ASSERT(guest_exception_count == 0);

        /*
         * Test to see if the instruction emulator is available (ie: the module
         * parameter 'kvm.force_emulation_prefix=1' is set).  This instruction
         * will #UD if it isn't available.
         */
        __asm__ __volatile__(KVM_FEP "nop");

        if (fep_available) {
                /* Let userspace know we aren't done. */
                GUEST_SYNC(0);

                /*
                 * Now run the same tests with the instruction emulator.
                 */
                data = test_em_rdmsr(MSR_IA32_XSS);
                GUEST_ASSERT(data == 0);
                GUEST_ASSERT(guest_exception_count == 0);
                test_em_wrmsr(MSR_IA32_XSS, 0);
                GUEST_ASSERT(guest_exception_count == 0);
                test_em_wrmsr(MSR_IA32_XSS, 1);
                GUEST_ASSERT(guest_exception_count == 1);

                test_em_rdmsr(MSR_IA32_FLUSH_CMD);
                GUEST_ASSERT(guest_exception_count == 1);
                test_em_wrmsr(MSR_IA32_FLUSH_CMD, 0);
                GUEST_ASSERT(guest_exception_count == 1);
                test_em_wrmsr(MSR_IA32_FLUSH_CMD, 1);
                GUEST_ASSERT(guest_exception_count == 0);

                test_em_wrmsr(MSR_NON_EXISTENT, 2);
                GUEST_ASSERT(guest_exception_count == 0);
                data = test_em_rdmsr(MSR_NON_EXISTENT);
                GUEST_ASSERT(data == 2);
                GUEST_ASSERT(guest_exception_count == 0);
        }

        GUEST_DONE();
}

static void guest_msr_calls(bool trapped)
{
        /* This goes into the in-kernel emulation */
        wrmsr(MSR_SYSCALL_MASK, 0);

        if (trapped) {
                /* This goes into user space emulation */
                GUEST_ASSERT(rdmsr(MSR_SYSCALL_MASK) == MSR_SYSCALL_MASK);
                GUEST_ASSERT(rdmsr(MSR_GS_BASE) == MSR_GS_BASE);
        } else {
                GUEST_ASSERT(rdmsr(MSR_SYSCALL_MASK) != MSR_SYSCALL_MASK);
                GUEST_ASSERT(rdmsr(MSR_GS_BASE) != MSR_GS_BASE);
        }

        /* If trapped == true, this goes into user space emulation */
        wrmsr(MSR_IA32_POWER_CTL, 0x1234);

        /* This goes into the in-kernel emulation */
        rdmsr(MSR_IA32_POWER_CTL);

        /* Invalid MSR, should always be handled by user space exit */
        GUEST_ASSERT(rdmsr(0xdeadbeef) == 0xdeadbeef);
        wrmsr(0xdeadbeef, 0x1234);
}

static void guest_code_filter_deny(void)
{
        guest_msr_calls(true);

        /*
         * Disable msr filtering, so that the kernel
         * handles everything in the next round
         */
        GUEST_SYNC(0);

        guest_msr_calls(false);

        GUEST_DONE();
}

static void guest_code_permission_bitmap(void)
{
        uint64_t data;

        data = test_rdmsr(MSR_FS_BASE);
        GUEST_ASSERT(data == MSR_FS_BASE);
        data = test_rdmsr(MSR_GS_BASE);
        GUEST_ASSERT(data != MSR_GS_BASE);

        /* Let userspace know to switch the filter */
        GUEST_SYNC(0);

        data = test_rdmsr(MSR_FS_BASE);
        GUEST_ASSERT(data != MSR_FS_BASE);
        data = test_rdmsr(MSR_GS_BASE);
        GUEST_ASSERT(data == MSR_GS_BASE);

        GUEST_DONE();
}

static void __guest_gp_handler(struct ex_regs *regs,
                               char *r_start, char *r_end,
                               char *w_start, char *w_end)
{
        if (regs->rip == (uintptr_t)r_start) {
                regs->rip = (uintptr_t)r_end;
                regs->rax = 0;
                regs->rdx = 0;
        } else if (regs->rip == (uintptr_t)w_start) {
                regs->rip = (uintptr_t)w_end;
        } else {
                GUEST_ASSERT(!"RIP is at an unknown location!");
        }

        ++guest_exception_count;
}

static void guest_gp_handler(struct ex_regs *regs)
{
        __guest_gp_handler(regs, &rdmsr_start, &rdmsr_end,
                           &wrmsr_start, &wrmsr_end);
}

static void guest_fep_gp_handler(struct ex_regs *regs)
{
        __guest_gp_handler(regs, &em_rdmsr_start, &em_rdmsr_end,
                           &em_wrmsr_start, &em_wrmsr_end);
}

static void guest_ud_handler(struct ex_regs *regs)
{
        fep_available = 0;
        regs->rip += KVM_FEP_LENGTH;
}

static void run_guest(struct kvm_vm *vm)
{
        int rc;

        rc = _vcpu_run(vm, VCPU_ID);
        TEST_ASSERT(rc == 0, "vcpu_run failed: %d\n", rc);
}

static void check_for_guest_assert(struct kvm_vm *vm)
{
        struct kvm_run *run = vcpu_state(vm, VCPU_ID);
        struct ucall uc;

        if (run->exit_reason == KVM_EXIT_IO &&
                get_ucall(vm, VCPU_ID, &uc) == UCALL_ABORT) {
                        TEST_FAIL("%s at %s:%ld", (const char *)uc.args[0],
                                __FILE__, uc.args[1]);
        }
}

static void process_rdmsr(struct kvm_vm *vm, uint32_t msr_index)
{
        struct kvm_run *run = vcpu_state(vm, VCPU_ID);

        check_for_guest_assert(vm);

        TEST_ASSERT(run->exit_reason == KVM_EXIT_X86_RDMSR,
                    "Unexpected exit reason: %u (%s),\n",
                    run->exit_reason,
                    exit_reason_str(run->exit_reason));
        TEST_ASSERT(run->msr.index == msr_index,
                        "Unexpected msr (0x%04x), expected 0x%04x",
                        run->msr.index, msr_index);

        switch (run->msr.index) {
        case MSR_IA32_XSS:
                run->msr.data = 0;
                break;
        case MSR_IA32_FLUSH_CMD:
                run->msr.error = 1;
                break;
        case MSR_NON_EXISTENT:
                run->msr.data = msr_non_existent_data;
                break;
        case MSR_FS_BASE:
                run->msr.data = MSR_FS_BASE;
                break;
        case MSR_GS_BASE:
                run->msr.data = MSR_GS_BASE;
                break;
        default:
                TEST_ASSERT(false, "Unexpected MSR: 0x%04x", run->msr.index);
        }
}

static void process_wrmsr(struct kvm_vm *vm, uint32_t msr_index)
{
        struct kvm_run *run = vcpu_state(vm, VCPU_ID);

        check_for_guest_assert(vm);

        TEST_ASSERT(run->exit_reason == KVM_EXIT_X86_WRMSR,
                    "Unexpected exit reason: %u (%s),\n",
                    run->exit_reason,
                    exit_reason_str(run->exit_reason));
        TEST_ASSERT(run->msr.index == msr_index,
                        "Unexpected msr (0x%04x), expected 0x%04x",
                        run->msr.index, msr_index);

        switch (run->msr.index) {
        case MSR_IA32_XSS:
                if (run->msr.data != 0)
                        run->msr.error = 1;
                break;
        case MSR_IA32_FLUSH_CMD:
                if (run->msr.data != 1)
                        run->msr.error = 1;
                break;
        case MSR_NON_EXISTENT:
                msr_non_existent_data = run->msr.data;
                break;
        default:
                TEST_ASSERT(false, "Unexpected MSR: 0x%04x", run->msr.index);
        }
}

static void process_ucall_done(struct kvm_vm *vm)
{
        struct kvm_run *run = vcpu_state(vm, VCPU_ID);
        struct ucall uc;

        check_for_guest_assert(vm);

        TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
                    "Unexpected exit reason: %u (%s)",
                    run->exit_reason,
                    exit_reason_str(run->exit_reason));

        TEST_ASSERT(get_ucall(vm, VCPU_ID, &uc) == UCALL_DONE,
                    "Unexpected ucall command: %lu, expected UCALL_DONE (%d)",
                    uc.cmd, UCALL_DONE);
}

static uint64_t process_ucall(struct kvm_vm *vm)
{
        struct kvm_run *run = vcpu_state(vm, VCPU_ID);
        struct ucall uc = {};

        check_for_guest_assert(vm);

        TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
                    "Unexpected exit reason: %u (%s)",
                    run->exit_reason,
                    exit_reason_str(run->exit_reason));

        switch (get_ucall(vm, VCPU_ID, &uc)) {
        case UCALL_SYNC:
                break;
        case UCALL_ABORT:
                check_for_guest_assert(vm);
                break;
        case UCALL_DONE:
                process_ucall_done(vm);
                break;
        default:
                TEST_ASSERT(false, "Unexpected ucall");
        }

        return uc.cmd;
}

static void run_guest_then_process_rdmsr(struct kvm_vm *vm, uint32_t msr_index)
{
        run_guest(vm);
        process_rdmsr(vm, msr_index);
}

static void run_guest_then_process_wrmsr(struct kvm_vm *vm, uint32_t msr_index)
{
        run_guest(vm);
        process_wrmsr(vm, msr_index);
}

static uint64_t run_guest_then_process_ucall(struct kvm_vm *vm)
{
        run_guest(vm);
        return process_ucall(vm);
}

static void run_guest_then_process_ucall_done(struct kvm_vm *vm)
{
        run_guest(vm);
        process_ucall_done(vm);
}

static void test_msr_filter_allow(void) {
        struct kvm_enable_cap cap = {
                .cap = KVM_CAP_X86_USER_SPACE_MSR,
                .args[0] = KVM_MSR_EXIT_REASON_FILTER,
        };
        struct kvm_vm *vm;
        int rc;

        /* Create VM */
        vm = vm_create_default(VCPU_ID, 0, guest_code_filter_allow);
        vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());

        rc = kvm_check_cap(KVM_CAP_X86_USER_SPACE_MSR);
        TEST_ASSERT(rc, "KVM_CAP_X86_USER_SPACE_MSR is available");
        vm_enable_cap(vm, &cap);

        rc = kvm_check_cap(KVM_CAP_X86_MSR_FILTER);
        TEST_ASSERT(rc, "KVM_CAP_X86_MSR_FILTER is available");

        vm_ioctl(vm, KVM_X86_SET_MSR_FILTER, &filter_allow);

        vm_init_descriptor_tables(vm);
        vcpu_init_descriptor_tables(vm, VCPU_ID);

        vm_handle_exception(vm, GP_VECTOR, guest_gp_handler);

        /* Process guest code userspace exits. */
        run_guest_then_process_rdmsr(vm, MSR_IA32_XSS);
        run_guest_then_process_wrmsr(vm, MSR_IA32_XSS);
        run_guest_then_process_wrmsr(vm, MSR_IA32_XSS);

        run_guest_then_process_rdmsr(vm, MSR_IA32_FLUSH_CMD);
        run_guest_then_process_wrmsr(vm, MSR_IA32_FLUSH_CMD);
        run_guest_then_process_wrmsr(vm, MSR_IA32_FLUSH_CMD);

        run_guest_then_process_wrmsr(vm, MSR_NON_EXISTENT);
        run_guest_then_process_rdmsr(vm, MSR_NON_EXISTENT);

        vm_handle_exception(vm, UD_VECTOR, guest_ud_handler);
        run_guest(vm);
        vm_handle_exception(vm, UD_VECTOR, NULL);

        if (process_ucall(vm) != UCALL_DONE) {
                vm_handle_exception(vm, GP_VECTOR, guest_fep_gp_handler);

                /* Process emulated rdmsr and wrmsr instructions. */
                run_guest_then_process_rdmsr(vm, MSR_IA32_XSS);
                run_guest_then_process_wrmsr(vm, MSR_IA32_XSS);
                run_guest_then_process_wrmsr(vm, MSR_IA32_XSS);

                run_guest_then_process_rdmsr(vm, MSR_IA32_FLUSH_CMD);
                run_guest_then_process_wrmsr(vm, MSR_IA32_FLUSH_CMD);
                run_guest_then_process_wrmsr(vm, MSR_IA32_FLUSH_CMD);

                run_guest_then_process_wrmsr(vm, MSR_NON_EXISTENT);
                run_guest_then_process_rdmsr(vm, MSR_NON_EXISTENT);

                /* Confirm the guest completed without issues. */
                run_guest_then_process_ucall_done(vm);
        } else {
                printf("To run the instruction emulated tests set the module parameter 'kvm.force_emulation_prefix=1'\n");
        }

        kvm_vm_free(vm);
}

static int handle_ucall(struct kvm_vm *vm)
{
        struct ucall uc;

        switch (get_ucall(vm, VCPU_ID, &uc)) {
        case UCALL_ABORT:
                TEST_FAIL("Guest assertion not met");
                break;
        case UCALL_SYNC:
                vm_ioctl(vm, KVM_X86_SET_MSR_FILTER, &no_filter_deny);
                break;
        case UCALL_DONE:
                return 1;
        default:
                TEST_FAIL("Unknown ucall %lu", uc.cmd);
        }

        return 0;
}

static void handle_rdmsr(struct kvm_run *run)
{
        run->msr.data = run->msr.index;
        msr_reads++;

        if (run->msr.index == MSR_SYSCALL_MASK ||
            run->msr.index == MSR_GS_BASE) {
                TEST_ASSERT(run->msr.reason == KVM_MSR_EXIT_REASON_FILTER,
                            "MSR read trap w/o access fault");
        }

        if (run->msr.index == 0xdeadbeef) {
                TEST_ASSERT(run->msr.reason == KVM_MSR_EXIT_REASON_UNKNOWN,
                            "MSR deadbeef read trap w/o inval fault");
        }
}

static void handle_wrmsr(struct kvm_run *run)
{
        /* ignore */
        msr_writes++;

        if (run->msr.index == MSR_IA32_POWER_CTL) {
                TEST_ASSERT(run->msr.data == 0x1234,
                            "MSR data for MSR_IA32_POWER_CTL incorrect");
                TEST_ASSERT(run->msr.reason == KVM_MSR_EXIT_REASON_FILTER,
                            "MSR_IA32_POWER_CTL trap w/o access fault");
        }

        if (run->msr.index == 0xdeadbeef) {
                TEST_ASSERT(run->msr.data == 0x1234,
                            "MSR data for deadbeef incorrect");
                TEST_ASSERT(run->msr.reason == KVM_MSR_EXIT_REASON_UNKNOWN,
                            "deadbeef trap w/o inval fault");
        }
}

static void test_msr_filter_deny(void) {
        struct kvm_enable_cap cap = {
                .cap = KVM_CAP_X86_USER_SPACE_MSR,
                .args[0] = KVM_MSR_EXIT_REASON_INVAL |
                           KVM_MSR_EXIT_REASON_UNKNOWN |
                           KVM_MSR_EXIT_REASON_FILTER,
        };
        struct kvm_vm *vm;
        struct kvm_run *run;
        int rc;

        /* Create VM */
        vm = vm_create_default(VCPU_ID, 0, guest_code_filter_deny);
        vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
        run = vcpu_state(vm, VCPU_ID);

        rc = kvm_check_cap(KVM_CAP_X86_USER_SPACE_MSR);
        TEST_ASSERT(rc, "KVM_CAP_X86_USER_SPACE_MSR is available");
        vm_enable_cap(vm, &cap);

        rc = kvm_check_cap(KVM_CAP_X86_MSR_FILTER);
        TEST_ASSERT(rc, "KVM_CAP_X86_MSR_FILTER is available");

        prepare_bitmaps();
        vm_ioctl(vm, KVM_X86_SET_MSR_FILTER, &filter_deny);

        while (1) {
                rc = _vcpu_run(vm, VCPU_ID);

                TEST_ASSERT(rc == 0, "vcpu_run failed: %d\n", rc);

                switch (run->exit_reason) {
                case KVM_EXIT_X86_RDMSR:
                        handle_rdmsr(run);
                        break;
                case KVM_EXIT_X86_WRMSR:
                        handle_wrmsr(run);
                        break;
                case KVM_EXIT_IO:
                        if (handle_ucall(vm))
                                goto done;
                        break;
                }

        }

done:
        TEST_ASSERT(msr_reads == 4, "Handled 4 rdmsr in user space");
        TEST_ASSERT(msr_writes == 3, "Handled 3 wrmsr in user space");

        kvm_vm_free(vm);
}

static void test_msr_permission_bitmap(void) {
        struct kvm_enable_cap cap = {
                .cap = KVM_CAP_X86_USER_SPACE_MSR,
                .args[0] = KVM_MSR_EXIT_REASON_FILTER,
        };
        struct kvm_vm *vm;
        int rc;

        /* Create VM */
        vm = vm_create_default(VCPU_ID, 0, guest_code_permission_bitmap);
        vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());

        rc = kvm_check_cap(KVM_CAP_X86_USER_SPACE_MSR);
        TEST_ASSERT(rc, "KVM_CAP_X86_USER_SPACE_MSR is available");
        vm_enable_cap(vm, &cap);

        rc = kvm_check_cap(KVM_CAP_X86_MSR_FILTER);
        TEST_ASSERT(rc, "KVM_CAP_X86_MSR_FILTER is available");

        vm_ioctl(vm, KVM_X86_SET_MSR_FILTER, &filter_fs);
        run_guest_then_process_rdmsr(vm, MSR_FS_BASE);
        TEST_ASSERT(run_guest_then_process_ucall(vm) == UCALL_SYNC, "Expected ucall state to be UCALL_SYNC.");
        vm_ioctl(vm, KVM_X86_SET_MSR_FILTER, &filter_gs);
        run_guest_then_process_rdmsr(vm, MSR_GS_BASE);
        run_guest_then_process_ucall_done(vm);

        kvm_vm_free(vm);
}

int main(int argc, char *argv[])
{
        /* Tell stdout not to buffer its content */
        setbuf(stdout, NULL);

        test_msr_filter_allow();

        test_msr_filter_deny();

        test_msr_permission_bitmap();

        return 0;
}