// SPDX-License-Identifier: GPL-2.0-only
#include <xen/xen.h>
#include <xen/events.h>
#include <xen/grant_table.h>
#include <xen/hvm.h>
#include <xen/interface/vcpu.h>
#include <xen/interface/xen.h>
#include <xen/interface/memory.h>
#include <xen/interface/hvm/params.h>
#include <xen/features.h>
#include <xen/platform_pci.h>
#include <xen/xenbus.h>
#include <xen/page.h>
#include <xen/interface/sched.h>
#include <xen/xen-ops.h>
#include <asm/xen/hypervisor.h>
#include <asm/xen/hypercall.h>
#include <asm/system_misc.h>
#include <asm/efi.h>
#include <linux/interrupt.h>
#include <linux/irqreturn.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/of_irq.h>
#include <linux/of_address.h>
#include <linux/cpuidle.h>
#include <linux/cpufreq.h>
#include <linux/cpu.h>
#include <linux/console.h>
#include <linux/pvclock_gtod.h>
#include <linux/reboot.h>
#include <linux/time64.h>
#include <linux/timekeeping.h>
#include <linux/timekeeper_internal.h>
#include <linux/acpi.h>

#include <linux/mm.h>

static struct start_info _xen_start_info;
struct start_info *xen_start_info = &_xen_start_info;
EXPORT_SYMBOL(xen_start_info);

enum xen_domain_type xen_domain_type = XEN_NATIVE;
EXPORT_SYMBOL(xen_domain_type);

struct shared_info xen_dummy_shared_info;
struct shared_info *HYPERVISOR_shared_info = (void *)&xen_dummy_shared_info;

DEFINE_PER_CPU(struct vcpu_info *, xen_vcpu);
static struct vcpu_info __percpu *xen_vcpu_info;

/* Linux <-> Xen vCPU id mapping */
DEFINE_PER_CPU(uint32_t, xen_vcpu_id);
EXPORT_PER_CPU_SYMBOL(xen_vcpu_id);

/* These are unused until we support booting "pre-ballooned" */
unsigned long xen_released_pages;
struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS] __initdata;

static __read_mostly unsigned int xen_events_irq;
static __read_mostly phys_addr_t xen_grant_frames;

#define GRANT_TABLE_INDEX   0
#define EXT_REGION_INDEX    1

uint32_t xen_start_flags;
EXPORT_SYMBOL(xen_start_flags);

int xen_unmap_domain_gfn_range(struct vm_area_struct *vma,
                               int nr, struct page **pages)
{
        return xen_xlate_unmap_gfn_range(vma, nr, pages);
}
EXPORT_SYMBOL_GPL(xen_unmap_domain_gfn_range);

static void xen_read_wallclock(struct timespec64 *ts)
{
        u32 version;
        struct timespec64 now, ts_monotonic;
        struct shared_info *s = HYPERVISOR_shared_info;
        struct pvclock_wall_clock *wall_clock = &(s->wc);

        /* get wallclock at system boot */
        do {
                version = wall_clock->version;
                rmb();          /* fetch version before time */
                now.tv_sec  = ((uint64_t)wall_clock->sec_hi << 32) | wall_clock->sec;
                now.tv_nsec = wall_clock->nsec;
                rmb();          /* fetch time before checking version */
        } while ((wall_clock->version & 1) || (version != wall_clock->version));

        /* time since system boot */
        ktime_get_ts64(&ts_monotonic);
        *ts = timespec64_add(now, ts_monotonic);
}

static int xen_pvclock_gtod_notify(struct notifier_block *nb,
                                   unsigned long was_set, void *priv)
{
        /* Protected by the calling core code serialization */
        static struct timespec64 next_sync;

        struct xen_platform_op op;
        struct timespec64 now, system_time;
        struct timekeeper *tk = priv;

        now.tv_sec = tk->xtime_sec;
        now.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
        system_time = timespec64_add(now, tk->wall_to_monotonic);

        /*
         * We only take the expensive HV call when the clock was set
         * or when the 11 minutes RTC synchronization time elapsed.
         */
        if (!was_set && timespec64_compare(&now, &next_sync) < 0)
                return NOTIFY_OK;

        op.cmd = XENPF_settime64;
        op.u.settime64.mbz = 0;
        op.u.settime64.secs = now.tv_sec;
        op.u.settime64.nsecs = now.tv_nsec;
        op.u.settime64.system_time = timespec64_to_ns(&system_time);
        (void)HYPERVISOR_platform_op(&op);

        /*
         * Move the next drift compensation time 11 minutes
         * ahead. That's emulating the sync_cmos_clock() update for
         * the hardware RTC.
         */
        next_sync = now;
        next_sync.tv_sec += 11 * 60;

        return NOTIFY_OK;
}

static struct notifier_block xen_pvclock_gtod_notifier = {
        .notifier_call = xen_pvclock_gtod_notify,
};

static int xen_starting_cpu(unsigned int cpu)
{
        struct vcpu_register_vcpu_info info;
        struct vcpu_info *vcpup;
        int err;

        /* 
         * VCPUOP_register_vcpu_info cannot be called twice for the same
         * vcpu, so if vcpu_info is already registered, just get out. This
         * can happen with cpu-hotplug.
         */
        if (per_cpu(xen_vcpu, cpu) != NULL)
                goto after_register_vcpu_info;

        pr_info("Xen: initializing cpu%d\n", cpu);
        vcpup = per_cpu_ptr(xen_vcpu_info, cpu);

        info.mfn = percpu_to_gfn(vcpup);
        info.offset = xen_offset_in_page(vcpup);

        err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info, xen_vcpu_nr(cpu),
                                 &info);
        BUG_ON(err);
        per_cpu(xen_vcpu, cpu) = vcpup;

        if (!xen_kernel_unmapped_at_usr())
                xen_setup_runstate_info(cpu);

after_register_vcpu_info:
        enable_percpu_irq(xen_events_irq, 0);
        return 0;
}

static int xen_dying_cpu(unsigned int cpu)
{
        disable_percpu_irq(xen_events_irq);
        return 0;
}

void xen_reboot(int reason)
{
        struct sched_shutdown r = { .reason = reason };
        int rc;

        rc = HYPERVISOR_sched_op(SCHEDOP_shutdown, &r);
        BUG_ON(rc);
}

static int xen_restart(struct notifier_block *nb, unsigned long action,
                       void *data)
{
        xen_reboot(SHUTDOWN_reboot);

        return NOTIFY_DONE;
}

static struct notifier_block xen_restart_nb = {
        .notifier_call = xen_restart,
        .priority = 192,
};

static void xen_power_off(void)
{
        xen_reboot(SHUTDOWN_poweroff);
}

static irqreturn_t xen_arm_callback(int irq, void *arg)
{
        xen_hvm_evtchn_do_upcall();
        return IRQ_HANDLED;
}

static __initdata struct {
        const char *compat;
        const char *prefix;
        const char *version;
        bool found;
} hyper_node = {"xen,xen", "xen,xen-", NULL, false};

static int __init fdt_find_hyper_node(unsigned long node, const char *uname,
                                      int depth, void *data)
{
        const void *s = NULL;
        int len;

        if (depth != 1 || strcmp(uname, "hypervisor") != 0)
                return 0;

        if (of_flat_dt_is_compatible(node, hyper_node.compat))
                hyper_node.found = true;

        s = of_get_flat_dt_prop(node, "compatible", &len);
        if (strlen(hyper_node.prefix) + 3  < len &&
            !strncmp(hyper_node.prefix, s, strlen(hyper_node.prefix)))
                hyper_node.version = s + strlen(hyper_node.prefix);

        /*
         * Check if Xen supports EFI by checking whether there is the
         * "/hypervisor/uefi" node in DT. If so, runtime services are available
         * through proxy functions (e.g. in case of Xen dom0 EFI implementation
         * they call special hypercall which executes relevant EFI functions)
         * and that is why they are always enabled.
         */
        if (IS_ENABLED(CONFIG_XEN_EFI)) {
                if ((of_get_flat_dt_subnode_by_name(node, "uefi") > 0) &&
                    !efi_runtime_disabled())
                        set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
        }

        return 0;
}

/*
 * see Documentation/devicetree/bindings/arm/xen.txt for the
 * documentation of the Xen Device Tree format.
 */
void __init xen_early_init(void)
{
        of_scan_flat_dt(fdt_find_hyper_node, NULL);
        if (!hyper_node.found) {
                pr_debug("No Xen support\n");
                return;
        }

        if (hyper_node.version == NULL) {
                pr_debug("Xen version not found\n");
                return;
        }

        pr_info("Xen %s support found\n", hyper_node.version);

        xen_domain_type = XEN_HVM_DOMAIN;

        xen_setup_features();

        if (xen_feature(XENFEAT_dom0))
                xen_start_flags |= SIF_INITDOMAIN|SIF_PRIVILEGED;

        if (!console_set_on_cmdline && !xen_initial_domain())
                add_preferred_console("hvc", 0, NULL);
}

static void __init xen_acpi_guest_init(void)
{
#ifdef CONFIG_ACPI
        struct xen_hvm_param a;
        int interrupt, trigger, polarity;

        a.domid = DOMID_SELF;
        a.index = HVM_PARAM_CALLBACK_IRQ;

        if (HYPERVISOR_hvm_op(HVMOP_get_param, &a)
            || (a.value >> 56) != HVM_PARAM_CALLBACK_TYPE_PPI) {
                xen_events_irq = 0;
                return;
        }

        interrupt = a.value & 0xff;
        trigger = ((a.value >> 8) & 0x1) ? ACPI_EDGE_SENSITIVE
                                         : ACPI_LEVEL_SENSITIVE;
        polarity = ((a.value >> 8) & 0x2) ? ACPI_ACTIVE_LOW
                                          : ACPI_ACTIVE_HIGH;
        xen_events_irq = acpi_register_gsi(NULL, interrupt, trigger, polarity);
#endif
}

#ifdef CONFIG_XEN_UNPOPULATED_ALLOC
/*
 * A type-less specific Xen resource which contains extended regions
 * (unused regions of guest physical address space provided by the hypervisor).
 */
static struct resource xen_resource = {
        .name = "Xen unused space",
};

int __init arch_xen_unpopulated_init(struct resource **res)
{
        struct device_node *np;
        struct resource *regs, *tmp_res;
        uint64_t min_gpaddr = -1, max_gpaddr = 0;
        unsigned int i, nr_reg = 0;
        int rc;

        if (!xen_domain())
                return -ENODEV;

        if (!acpi_disabled)
                return -ENODEV;

        np = of_find_compatible_node(NULL, NULL, "xen,xen");
        if (WARN_ON(!np))
                return -ENODEV;

        /* Skip region 0 which is reserved for grant table space */
        while (of_get_address(np, nr_reg + EXT_REGION_INDEX, NULL, NULL))
                nr_reg++;

        if (!nr_reg) {
                pr_err("No extended regions are found\n");
                of_node_put(np);
                return -EINVAL;
        }

        regs = kcalloc(nr_reg, sizeof(*regs), GFP_KERNEL);
        if (!regs) {
                of_node_put(np);
                return -ENOMEM;
        }

        /*
         * Create resource from extended regions provided by the hypervisor to be
         * used as unused address space for Xen scratch pages.
         */
        for (i = 0; i < nr_reg; i++) {
                rc = of_address_to_resource(np, i + EXT_REGION_INDEX, &regs[i]);
                if (rc)
                        goto err;

                if (max_gpaddr < regs[i].end)
                        max_gpaddr = regs[i].end;
                if (min_gpaddr > regs[i].start)
                        min_gpaddr = regs[i].start;
        }

        xen_resource.start = min_gpaddr;
        xen_resource.end = max_gpaddr;

        /*
         * Mark holes between extended regions as unavailable. The rest of that
         * address space will be available for the allocation.
         */
        for (i = 1; i < nr_reg; i++) {
                resource_size_t start, end;

                /* There is an overlap between regions */
                if (regs[i - 1].end + 1 > regs[i].start) {
                        rc = -EINVAL;
                        goto err;
                }

                /* There is no hole between regions */
                if (regs[i - 1].end + 1 == regs[i].start)
                        continue;

                start = regs[i - 1].end + 1;
                end = regs[i].start - 1;

                tmp_res = kzalloc(sizeof(*tmp_res), GFP_KERNEL);
                if (!tmp_res) {
                        rc = -ENOMEM;
                        goto err;
                }

                tmp_res->name = "Unavailable space";
                tmp_res->start = start;
                tmp_res->end = end;

                rc = insert_resource(&xen_resource, tmp_res);
                if (rc) {
                        pr_err("Cannot insert resource %pR (%d)\n", tmp_res, rc);
                        kfree(tmp_res);
                        goto err;
                }
        }

        *res = &xen_resource;

err:
        of_node_put(np);
        kfree(regs);
        return rc;
}
#endif

static void __init xen_dt_guest_init(void)
{
        struct device_node *xen_node;
        struct resource res;

        xen_node = of_find_compatible_node(NULL, NULL, "xen,xen");
        if (!xen_node) {
                pr_err("Xen support was detected before, but it has disappeared\n");
                return;
        }

        xen_events_irq = irq_of_parse_and_map(xen_node, 0);

        if (of_address_to_resource(xen_node, GRANT_TABLE_INDEX, &res)) {
                pr_err("Xen grant table region is not found\n");
                of_node_put(xen_node);
                return;
        }
        of_node_put(xen_node);
        xen_grant_frames = res.start;
}

static int __init xen_guest_init(void)
{
        struct xen_add_to_physmap xatp;
        struct shared_info *shared_info_page = NULL;
        int rc, cpu;

        if (!xen_domain())
                return 0;

        if (!acpi_disabled)
                xen_acpi_guest_init();
        else
                xen_dt_guest_init();

        if (!xen_events_irq) {
                pr_err("Xen event channel interrupt not found\n");
                return -ENODEV;
        }

        /*
         * The fdt parsing codes have set EFI_RUNTIME_SERVICES if Xen EFI
         * parameters are found. Force enable runtime services.
         */
        if (efi_enabled(EFI_RUNTIME_SERVICES))
                xen_efi_runtime_setup();

        shared_info_page = (struct shared_info *)get_zeroed_page(GFP_KERNEL);

        if (!shared_info_page) {
                pr_err("not enough memory\n");
                return -ENOMEM;
        }
        xatp.domid = DOMID_SELF;
        xatp.idx = 0;
        xatp.space = XENMAPSPACE_shared_info;
        xatp.gpfn = virt_to_gfn(shared_info_page);
        if (HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp))
                BUG();

        HYPERVISOR_shared_info = (struct shared_info *)shared_info_page;

        /* xen_vcpu is a pointer to the vcpu_info struct in the shared_info
         * page, we use it in the event channel upcall and in some pvclock
         * related functions. 
         * The shared info contains exactly 1 CPU (the boot CPU). The guest
         * is required to use VCPUOP_register_vcpu_info to place vcpu info
         * for secondary CPUs as they are brought up.
         * For uniformity we use VCPUOP_register_vcpu_info even on cpu0.
         */
        xen_vcpu_info = alloc_percpu(struct vcpu_info);
        if (xen_vcpu_info == NULL)
                return -ENOMEM;

        /* Direct vCPU id mapping for ARM guests. */
        for_each_possible_cpu(cpu)
                per_cpu(xen_vcpu_id, cpu) = cpu;

        if (!xen_grant_frames) {
                xen_auto_xlat_grant_frames.count = gnttab_max_grant_frames();
                rc = xen_xlate_map_ballooned_pages(&xen_auto_xlat_grant_frames.pfn,
                                                                                   &xen_auto_xlat_grant_frames.vaddr,
                                                                                   xen_auto_xlat_grant_frames.count);
        } else
                rc = gnttab_setup_auto_xlat_frames(xen_grant_frames);
        if (rc) {
                free_percpu(xen_vcpu_info);
                return rc;
        }
        gnttab_init();

        /*
         * Making sure board specific code will not set up ops for
         * cpu idle and cpu freq.
         */
        disable_cpuidle();
        disable_cpufreq();

        xen_init_IRQ();

        if (request_percpu_irq(xen_events_irq, xen_arm_callback,
                               "events", &xen_vcpu)) {
                pr_err("Error request IRQ %d\n", xen_events_irq);
                return -EINVAL;
        }

        if (!xen_kernel_unmapped_at_usr())
                xen_time_setup_guest();

        if (xen_initial_domain())
                pvclock_gtod_register_notifier(&xen_pvclock_gtod_notifier);

        return cpuhp_setup_state(CPUHP_AP_ARM_XEN_STARTING,
                                 "arm/xen:starting", xen_starting_cpu,
                                 xen_dying_cpu);
}
early_initcall(xen_guest_init);

static int __init xen_pm_init(void)
{
        if (!xen_domain())
                return -ENODEV;

        pm_power_off = xen_power_off;
        register_restart_handler(&xen_restart_nb);
        if (!xen_initial_domain()) {
                struct timespec64 ts;
                xen_read_wallclock(&ts);
                do_settimeofday64(&ts);
        }

        return 0;
}
late_initcall(xen_pm_init);


/* empty stubs */
void xen_arch_pre_suspend(void) { }
void xen_arch_post_suspend(int suspend_cancelled) { }
void xen_timer_resume(void) { }
void xen_arch_resume(void) { }
void xen_arch_suspend(void) { }


/* In the hypercall.S file. */
EXPORT_SYMBOL_GPL(HYPERVISOR_event_channel_op);
EXPORT_SYMBOL_GPL(HYPERVISOR_grant_table_op);
EXPORT_SYMBOL_GPL(HYPERVISOR_xen_version);
EXPORT_SYMBOL_GPL(HYPERVISOR_console_io);
EXPORT_SYMBOL_GPL(HYPERVISOR_sched_op);
EXPORT_SYMBOL_GPL(HYPERVISOR_hvm_op);
EXPORT_SYMBOL_GPL(HYPERVISOR_memory_op);
EXPORT_SYMBOL_GPL(HYPERVISOR_physdev_op);
EXPORT_SYMBOL_GPL(HYPERVISOR_vcpu_op);
EXPORT_SYMBOL_GPL(HYPERVISOR_platform_op_raw);
EXPORT_SYMBOL_GPL(HYPERVISOR_multicall);
EXPORT_SYMBOL_GPL(HYPERVISOR_vm_assist);
EXPORT_SYMBOL_GPL(HYPERVISOR_dm_op);
EXPORT_SYMBOL_GPL(privcmd_call);