/*
 * This file and its contents are supplied under the terms of the
 * Common Development and Distribution License ("CDDL"), version 1.0.
 * You may only use this file in accordance with the terms of version
 * 1.0 of the CDDL.
 *
 * A full copy of the text of the CDDL should have accompanied this
 * source.  A copy of the CDDL is also available via the Internet at
 * http://www.illumos.org/license/CDDL.
 */

/*
 * Copyright 2024 Oxide Computer Company
 */

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <libgen.h>
#include <sys/stat.h>
#include <errno.h>
#include <err.h>
#include <assert.h>
#include <sys/sysmacros.h>
#include <stdbool.h>

#include <sys/vmm.h>
#include <sys/vmm_dev.h>
#include <sys/vmm_data.h>
#include <vmmapi.h>

#include "common.h"

#define APIC_ADDR_TIMER_ICR     0xfee00380
#define APIC_ADDR_TIMER_CCR     0xfee00390

#define TIMER_TEST_VAL  0x10000

static void
test_ccr_clamp(int vmfd, struct vcpu *vcpu)
{
        /* Pause the instance before attempting to manipulate vlapic data */
        if (ioctl(vmfd, VM_PAUSE, 0) != 0) {
                err(EXIT_FAILURE, "VM_PAUSE failed");
        }

        struct vdi_lapic_v1 lapic_data;
        struct vm_data_xfer xfer = {
                .vdx_vcpuid = 0,
                .vdx_class = VDC_LAPIC,
                .vdx_version = 1,
                .vdx_len = sizeof (lapic_data),
                .vdx_data = &lapic_data,
        };

        /* Read the existing lapic data to get a baseline */
        if (ioctl(vmfd, VM_DATA_READ, &xfer) != 0) {
                err(EXIT_FAILURE, "VM_DATA_READ of lapic failed");
        }

        /* Writing that exact same data back should be fine */
        if (ioctl(vmfd, VM_DATA_WRITE, &xfer) != 0) {
                err(EXIT_FAILURE, "VM_DATA_WRITE of lapic failed");
        }

        /* Simulate ICR being loaded with a meaningful (but short) value */
        lapic_data.vl_lapic.vlp_icr_timer = TIMER_TEST_VAL;
        /*
         * Pretend as if timer is scheduled to fire 100s (in the future) after
         * VM boot time.  With the ICR value, this should trigger the overage
         * detection and clamping.
         */
        lapic_data.vl_timer_target = 1000000000UL * 100;

        /* Try to write the outlandish timer result */
        if (ioctl(vmfd, VM_DATA_WRITE, &xfer) != 0) {
                err(EXIT_FAILURE, "VM_DATA_WRITE of lapic failed");
        }

        /*
         * The timer will not actually be scheduled (and thus observable via
         * CCR) until the instance is resumed...
         */
        if (ioctl(vmfd, VM_RESUME, 0) != 0) {
                err(EXIT_FAILURE, "VM_RESUME failed");
        }

        /* Now simulate a read of CCR from that LAPIC */
        uint64_t ccr_value = 0;
        int error = vm_readwrite_kernemu_device(vcpu, APIC_ADDR_TIMER_CCR,
            false, 4, &ccr_value);
        if (error != 0) {
                err(EXIT_FAILURE, "could not emulate MMIO of LAPIC CCR");
        }
        if (ccr_value != TIMER_TEST_VAL) {
                errx(EXIT_FAILURE, "CCR not clamped: %lx != %x",
                    ccr_value, TIMER_TEST_VAL);
        }
}

static void
test_timer_icr_constraints(int vmfd, struct vcpu *vcpu)
{
        /* Pause instance before our shenanigans */
        if (ioctl(vmfd, VM_PAUSE, 0) != 0) {
                err(EXIT_FAILURE, "VM_PAUSE failed");
        }

        /* Load a TIMER_ICR value */
        uint64_t icr_value = 1 << 30;
        int error = vm_readwrite_kernemu_device(vcpu, APIC_ADDR_TIMER_CCR,
            true, 4, &icr_value);
        if (error != 0) {
                err(EXIT_FAILURE, "failed to load timer ICR value");
        }

        struct vdi_lapic_v1 lapic_data;
        struct vm_data_xfer xfer = {
                .vdx_vcpuid = 0,
                .vdx_class = VDC_LAPIC,
                .vdx_version = 1,
                .vdx_len = sizeof (lapic_data),
                .vdx_data = &lapic_data,
        };

        if (ioctl(vmfd, VM_DATA_READ, &xfer) != 0) {
                err(EXIT_FAILURE, "VM_DATA_READ of lapic failed");
        }

        /* Confirm that ICR value is set, and timer is scheduled */
        if (lapic_data.vl_lapic.vlp_icr_timer == 0) {
                errx(EXIT_FAILURE, "ICR_TIMER is 0");
        }
        if (lapic_data.vl_timer_target == 0) {
                errx(EXIT_FAILURE, "vlapic timer not scheduled");
        }

        /* Reset vCPU to clear timer state from LAPIC */
        if (vcpu_reset(vcpu) != 0) {
                err(EXIT_FAILURE, "vcpu_reset() failed");
        }

        /* Re-read vlapic, and confirm zeroed bits */
        if (ioctl(vmfd, VM_DATA_READ, &xfer) != 0) {
                err(EXIT_FAILURE, "VM_DATA_READ of lapic failed");
        }
        if (lapic_data.vl_lapic.vlp_icr_timer != 0) {
                errx(EXIT_FAILURE, "ICR_TIMER is not 0");
        }
        if (lapic_data.vl_timer_target != 0) {
                errx(EXIT_FAILURE, "vlapic timer should not be scheduled");
        }

        /*
         * Try to load a vlapic payload with timer scheduled but icr_timer still
         * zeroed out.
         */
        lapic_data.vl_timer_target = 1 << 20;
        lapic_data.vl_lapic.vlp_icr_timer = 0;

        if (ioctl(vmfd, VM_DATA_WRITE, &xfer) == 0) {
                errx(EXIT_FAILURE,
                    "VM_DATA_WRITE of invalid lapic data should fail");
        }
}

int
main(int argc, char *argv[])
{
        const char *suite_name = basename(argv[0]);
        struct vmctx *ctx;
        struct vcpu *vcpu;

        ctx = create_test_vm(suite_name);
        if (ctx == NULL) {
                errx(EXIT_FAILURE, "could not open test VM");
        }

        if ((vcpu = vm_vcpu_open(ctx, 0)) == NULL) {
                err(EXIT_FAILURE, "Could not open vcpu0");
        }

        if (vm_activate_cpu(vcpu) != 0) {
                err(EXIT_FAILURE, "could not activate vcpu0");
        }

        const int vmfd = vm_get_device_fd(ctx);

        test_ccr_clamp(vmfd, vcpu);
        test_timer_icr_constraints(vmfd, vcpu);

        vm_destroy(ctx);
        (void) printf("%s\tPASS\n", suite_name);
        return (EXIT_SUCCESS);
}