/*
 * VMware Detection code.
 *
 * Copyright (C) 2008, VMware, Inc.
 * Author : Alok N Kataria <akataria@vmware.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 * NON INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */

#include <linux/dmi.h>
#include <linux/init.h>
#include <linux/export.h>
#include <linux/clocksource.h>
#include <linux/cpu.h>
#include <linux/reboot.h>
#include <asm/div64.h>
#include <asm/x86_init.h>
#include <asm/hypervisor.h>
#include <asm/timer.h>
#include <asm/apic.h>
#include <asm/vmware.h>

#undef pr_fmt
#define pr_fmt(fmt)     "vmware: " fmt

#define CPUID_VMWARE_INFO_LEAF               0x40000000
#define CPUID_VMWARE_FEATURES_LEAF           0x40000010
#define CPUID_VMWARE_FEATURES_ECX_VMMCALL    BIT(0)
#define CPUID_VMWARE_FEATURES_ECX_VMCALL     BIT(1)

#define VMWARE_HYPERVISOR_MAGIC 0x564D5868

#define VMWARE_CMD_GETVERSION    10
#define VMWARE_CMD_GETHZ         45
#define VMWARE_CMD_GETVCPU_INFO  68
#define VMWARE_CMD_LEGACY_X2APIC  3
#define VMWARE_CMD_VCPU_RESERVED 31
#define VMWARE_CMD_STEALCLOCK    91

#define STEALCLOCK_NOT_AVAILABLE (-1)
#define STEALCLOCK_DISABLED        0
#define STEALCLOCK_ENABLED         1

#define VMWARE_PORT(cmd, eax, ebx, ecx, edx)                            \
        __asm__("inl (%%dx), %%eax" :                                   \
                "=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :            \
                "a"(VMWARE_HYPERVISOR_MAGIC),                           \
                "c"(VMWARE_CMD_##cmd),                                  \
                "d"(VMWARE_HYPERVISOR_PORT), "b"(UINT_MAX) :            \
                "memory")

#define VMWARE_VMCALL(cmd, eax, ebx, ecx, edx)                          \
        __asm__("vmcall" :                                              \
                "=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :            \
                "a"(VMWARE_HYPERVISOR_MAGIC),                           \
                "c"(VMWARE_CMD_##cmd),                                  \
                "d"(0), "b"(UINT_MAX) :                                 \
                "memory")

#define VMWARE_VMMCALL(cmd, eax, ebx, ecx, edx)                         \
        __asm__("vmmcall" :                                             \
                "=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :            \
                "a"(VMWARE_HYPERVISOR_MAGIC),                           \
                "c"(VMWARE_CMD_##cmd),                                  \
                "d"(0), "b"(UINT_MAX) :                                 \
                "memory")

#define VMWARE_CMD(cmd, eax, ebx, ecx, edx) do {                \
        switch (vmware_hypercall_mode) {                        \
        case CPUID_VMWARE_FEATURES_ECX_VMCALL:                  \
                VMWARE_VMCALL(cmd, eax, ebx, ecx, edx);         \
                break;                                          \
        case CPUID_VMWARE_FEATURES_ECX_VMMCALL:                 \
                VMWARE_VMMCALL(cmd, eax, ebx, ecx, edx);        \
                break;                                          \
        default:                                                \
                VMWARE_PORT(cmd, eax, ebx, ecx, edx);           \
                break;                                          \
        }                                                       \
        } while (0)

struct vmware_steal_time {
        union {
                uint64_t clock; /* stolen time counter in units of vtsc */
                struct {
                        /* only for little-endian */
                        uint32_t clock_low;
                        uint32_t clock_high;
                };
        };
        uint64_t reserved[7];
};

static unsigned long vmware_tsc_khz __ro_after_init;
static u8 vmware_hypercall_mode     __ro_after_init;

static inline int __vmware_platform(void)
{
        uint32_t eax, ebx, ecx, edx;
        VMWARE_CMD(GETVERSION, eax, ebx, ecx, edx);
        return eax != (uint32_t)-1 && ebx == VMWARE_HYPERVISOR_MAGIC;
}

static unsigned long vmware_get_tsc_khz(void)
{
        return vmware_tsc_khz;
}

#ifdef CONFIG_PARAVIRT
static struct cyc2ns_data vmware_cyc2ns __ro_after_init;
static bool vmw_sched_clock __initdata = true;
static DEFINE_PER_CPU_DECRYPTED(struct vmware_steal_time, vmw_steal_time) __aligned(64);
static bool has_steal_clock;
static bool steal_acc __initdata = true; /* steal time accounting */

static __init int setup_vmw_sched_clock(char *s)
{
        vmw_sched_clock = false;
        return 0;
}
early_param("no-vmw-sched-clock", setup_vmw_sched_clock);

static __init int parse_no_stealacc(char *arg)
{
        steal_acc = false;
        return 0;
}
early_param("no-steal-acc", parse_no_stealacc);

static unsigned long long notrace vmware_sched_clock(void)
{
        unsigned long long ns;

        ns = mul_u64_u32_shr(rdtsc(), vmware_cyc2ns.cyc2ns_mul,
                             vmware_cyc2ns.cyc2ns_shift);
        ns -= vmware_cyc2ns.cyc2ns_offset;
        return ns;
}

static void __init vmware_cyc2ns_setup(void)
{
        struct cyc2ns_data *d = &vmware_cyc2ns;
        unsigned long long tsc_now = rdtsc();

        clocks_calc_mult_shift(&d->cyc2ns_mul, &d->cyc2ns_shift,
                               vmware_tsc_khz, NSEC_PER_MSEC, 0);
        d->cyc2ns_offset = mul_u64_u32_shr(tsc_now, d->cyc2ns_mul,
                                           d->cyc2ns_shift);

        pr_info("using clock offset of %llu ns\n", d->cyc2ns_offset);
}

static int vmware_cmd_stealclock(uint32_t arg1, uint32_t arg2)
{
        uint32_t result, info;

        asm volatile (VMWARE_HYPERCALL :
                "=a"(result),
                "=c"(info) :
                "a"(VMWARE_HYPERVISOR_MAGIC),
                "b"(0),
                "c"(VMWARE_CMD_STEALCLOCK),
                "d"(0),
                "S"(arg1),
                "D"(arg2) :
                "memory");
        return result;
}

static bool stealclock_enable(phys_addr_t pa)
{
        return vmware_cmd_stealclock(upper_32_bits(pa),
                                     lower_32_bits(pa)) == STEALCLOCK_ENABLED;
}

static int __stealclock_disable(void)
{
        return vmware_cmd_stealclock(0, 1);
}

static void stealclock_disable(void)
{
        __stealclock_disable();
}

static bool vmware_is_stealclock_available(void)
{
        return __stealclock_disable() != STEALCLOCK_NOT_AVAILABLE;
}

/**
 * vmware_steal_clock() - read the per-cpu steal clock
 * @cpu:            the cpu number whose steal clock we want to read
 *
 * The function reads the steal clock if we are on a 64-bit system, otherwise
 * reads it in parts, checking that the high part didn't change in the
 * meantime.
 *
 * Return:
 *      The steal clock reading in ns.
 */
static uint64_t vmware_steal_clock(int cpu)
{
        struct vmware_steal_time *steal = &per_cpu(vmw_steal_time, cpu);
        uint64_t clock;

        if (IS_ENABLED(CONFIG_64BIT))
                clock = READ_ONCE(steal->clock);
        else {
                uint32_t initial_high, low, high;

                do {
                        initial_high = READ_ONCE(steal->clock_high);
                        /* Do not reorder initial_high and high readings */
                        virt_rmb();
                        low = READ_ONCE(steal->clock_low);
                        /* Keep low reading in between */
                        virt_rmb();
                        high = READ_ONCE(steal->clock_high);
                } while (initial_high != high);

                clock = ((uint64_t)high << 32) | low;
        }

        return mul_u64_u32_shr(clock, vmware_cyc2ns.cyc2ns_mul,
                             vmware_cyc2ns.cyc2ns_shift);
}

static void vmware_register_steal_time(void)
{
        int cpu = smp_processor_id();
        struct vmware_steal_time *st = &per_cpu(vmw_steal_time, cpu);

        if (!has_steal_clock)
                return;

        if (!stealclock_enable(slow_virt_to_phys(st))) {
                has_steal_clock = false;
                return;
        }

        pr_info("vmware-stealtime: cpu %d, pa %llx\n",
                cpu, (unsigned long long) slow_virt_to_phys(st));
}

static void vmware_disable_steal_time(void)
{
        if (!has_steal_clock)
                return;

        stealclock_disable();
}

static void vmware_guest_cpu_init(void)
{
        if (has_steal_clock)
                vmware_register_steal_time();
}

static void vmware_pv_guest_cpu_reboot(void *unused)
{
        vmware_disable_steal_time();
}

static int vmware_pv_reboot_notify(struct notifier_block *nb,
                                unsigned long code, void *unused)
{
        if (code == SYS_RESTART)
                on_each_cpu(vmware_pv_guest_cpu_reboot, NULL, 1);
        return NOTIFY_DONE;
}

static struct notifier_block vmware_pv_reboot_nb = {
        .notifier_call = vmware_pv_reboot_notify,
};

#ifdef CONFIG_SMP
static void __init vmware_smp_prepare_boot_cpu(void)
{
        vmware_guest_cpu_init();
        native_smp_prepare_boot_cpu();
}

static int vmware_cpu_online(unsigned int cpu)
{
        local_irq_disable();
        vmware_guest_cpu_init();
        local_irq_enable();
        return 0;
}

static int vmware_cpu_down_prepare(unsigned int cpu)
{
        local_irq_disable();
        vmware_disable_steal_time();
        local_irq_enable();
        return 0;
}
#endif

static __init int activate_jump_labels(void)
{
        if (has_steal_clock) {
                static_key_slow_inc(&paravirt_steal_enabled);
                if (steal_acc)
                        static_key_slow_inc(&paravirt_steal_rq_enabled);
        }

        return 0;
}
arch_initcall(activate_jump_labels);

static void __init vmware_paravirt_ops_setup(void)
{
        pv_info.name = "VMware hypervisor";
        pv_ops.cpu.io_delay = paravirt_nop;

        if (vmware_tsc_khz == 0)
                return;

        vmware_cyc2ns_setup();

        if (vmw_sched_clock)
                pv_ops.time.sched_clock = vmware_sched_clock;

        if (vmware_is_stealclock_available()) {
                has_steal_clock = true;
                pv_ops.time.steal_clock = vmware_steal_clock;

                /* We use reboot notifier only to disable steal clock */
                register_reboot_notifier(&vmware_pv_reboot_nb);

#ifdef CONFIG_SMP
                smp_ops.smp_prepare_boot_cpu =
                        vmware_smp_prepare_boot_cpu;
                if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
                                              "x86/vmware:online",
                                              vmware_cpu_online,
                                              vmware_cpu_down_prepare) < 0)
                        pr_err("vmware_guest: Failed to install cpu hotplug callbacks\n");
#else
                vmware_guest_cpu_init();
#endif
        }
}
#else
#define vmware_paravirt_ops_setup() do {} while (0)
#endif

/*
 * VMware hypervisor takes care of exporting a reliable TSC to the guest.
 * Still, due to timing difference when running on virtual cpus, the TSC can
 * be marked as unstable in some cases. For example, the TSC sync check at
 * bootup can fail due to a marginal offset between vcpus' TSCs (though the
 * TSCs do not drift from each other).  Also, the ACPI PM timer clocksource
 * is not suitable as a watchdog when running on a hypervisor because the
 * kernel may miss a wrap of the counter if the vcpu is descheduled for a
 * long time. To skip these checks at runtime we set these capability bits,
 * so that the kernel could just trust the hypervisor with providing a
 * reliable virtual TSC that is suitable for timekeeping.
 */
static void __init vmware_set_capabilities(void)
{
        setup_force_cpu_cap(X86_FEATURE_CONSTANT_TSC);
        setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
        if (vmware_hypercall_mode == CPUID_VMWARE_FEATURES_ECX_VMCALL)
                setup_force_cpu_cap(X86_FEATURE_VMCALL);
        else if (vmware_hypercall_mode == CPUID_VMWARE_FEATURES_ECX_VMMCALL)
                setup_force_cpu_cap(X86_FEATURE_VMW_VMMCALL);
}

static void __init vmware_platform_setup(void)
{
        uint32_t eax, ebx, ecx, edx;
        uint64_t lpj, tsc_khz;

        VMWARE_CMD(GETHZ, eax, ebx, ecx, edx);

        if (ebx != UINT_MAX) {
                lpj = tsc_khz = eax | (((uint64_t)ebx) << 32);
                do_div(tsc_khz, 1000);
                WARN_ON(tsc_khz >> 32);
                pr_info("TSC freq read from hypervisor : %lu.%03lu MHz\n",
                        (unsigned long) tsc_khz / 1000,
                        (unsigned long) tsc_khz % 1000);

                if (!preset_lpj) {
                        do_div(lpj, HZ);
                        preset_lpj = lpj;
                }

                vmware_tsc_khz = tsc_khz;
                x86_platform.calibrate_tsc = vmware_get_tsc_khz;
                x86_platform.calibrate_cpu = vmware_get_tsc_khz;

#ifdef CONFIG_X86_LOCAL_APIC
                /* Skip lapic calibration since we know the bus frequency. */
                lapic_timer_period = ecx / HZ;
                pr_info("Host bus clock speed read from hypervisor : %u Hz\n",
                        ecx);
#endif
        } else {
                pr_warn("Failed to get TSC freq from the hypervisor\n");
        }

        vmware_paravirt_ops_setup();

#ifdef CONFIG_X86_IO_APIC
        no_timer_check = 1;
#endif

        vmware_set_capabilities();
}

static u8 __init vmware_select_hypercall(void)
{
        int eax, ebx, ecx, edx;

        cpuid(CPUID_VMWARE_FEATURES_LEAF, &eax, &ebx, &ecx, &edx);
        return (ecx & (CPUID_VMWARE_FEATURES_ECX_VMMCALL |
                       CPUID_VMWARE_FEATURES_ECX_VMCALL));
}

/*
 * While checking the dmi string information, just checking the product
 * serial key should be enough, as this will always have a VMware
 * specific string when running under VMware hypervisor.
 * If !boot_cpu_has(X86_FEATURE_HYPERVISOR), vmware_hypercall_mode
 * intentionally defaults to 0.
 */
static uint32_t __init vmware_platform(void)
{
        if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
                unsigned int eax;
                unsigned int hyper_vendor_id[3];

                cpuid(CPUID_VMWARE_INFO_LEAF, &eax, &hyper_vendor_id[0],
                      &hyper_vendor_id[1], &hyper_vendor_id[2]);
                if (!memcmp(hyper_vendor_id, "VMwareVMware", 12)) {
                        if (eax >= CPUID_VMWARE_FEATURES_LEAF)
                                vmware_hypercall_mode =
                                        vmware_select_hypercall();

                        pr_info("hypercall mode: 0x%02x\n",
                                (unsigned int) vmware_hypercall_mode);

                        return CPUID_VMWARE_INFO_LEAF;
                }
        } else if (dmi_available && dmi_name_in_serial("VMware") &&
                   __vmware_platform())
                return 1;

        return 0;
}

/* Checks if hypervisor supports x2apic without VT-D interrupt remapping. */
static bool __init vmware_legacy_x2apic_available(void)
{
        uint32_t eax, ebx, ecx, edx;
        VMWARE_CMD(GETVCPU_INFO, eax, ebx, ecx, edx);
        return (eax & (1 << VMWARE_CMD_VCPU_RESERVED)) == 0 &&
               (eax & (1 << VMWARE_CMD_LEGACY_X2APIC)) != 0;
}

const __initconst struct hypervisor_x86 x86_hyper_vmware = {
        .name                   = "VMware",
        .detect                 = vmware_platform,
        .type                   = X86_HYPER_VMWARE,
        .init.init_platform     = vmware_platform_setup,
        .init.x2apic_available  = vmware_legacy_x2apic_available,
};