// SPDX-License-Identifier: GPL-2.0

#include <linux/acpi.h>
#include <linux/cpu.h>
#include <linux/kexec.h>
#include <linux/memblock.h>

#include <xen/features.h>
#include <xen/events.h>
#include <xen/interface/memory.h>

#include <asm/cpu.h>
#include <asm/smp.h>
#include <asm/io_apic.h>
#include <asm/reboot.h>
#include <asm/setup.h>
#include <asm/idtentry.h>
#include <asm/hypervisor.h>
#include <asm/e820/api.h>
#include <asm/early_ioremap.h>

#include <asm/xen/cpuid.h>
#include <asm/xen/hypervisor.h>
#include <asm/xen/page.h>

#include "xen-ops.h"
#include "mmu.h"
#include "smp.h"

static unsigned long shared_info_pfn;

void xen_hvm_init_shared_info(void)
{
        struct xen_add_to_physmap xatp;

        xatp.domid = DOMID_SELF;
        xatp.idx = 0;
        xatp.space = XENMAPSPACE_shared_info;
        xatp.gpfn = shared_info_pfn;
        if (HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp))
                BUG();
}

static void __init reserve_shared_info(void)
{
        u64 pa;

        /*
         * Search for a free page starting at 4kB physical address.
         * Low memory is preferred to avoid an EPT large page split up
         * by the mapping.
         * Starting below X86_RESERVE_LOW (usually 64kB) is fine as
         * the BIOS used for HVM guests is well behaved and won't
         * clobber memory other than the first 4kB.
         */
        for (pa = PAGE_SIZE;
             !e820__mapped_all(pa, pa + PAGE_SIZE, E820_TYPE_RAM) ||
             memblock_is_reserved(pa);
             pa += PAGE_SIZE)
                ;

        shared_info_pfn = PHYS_PFN(pa);

        memblock_reserve(pa, PAGE_SIZE);
        HYPERVISOR_shared_info = early_memremap(pa, PAGE_SIZE);
}

static void __init xen_hvm_init_mem_mapping(void)
{
        early_memunmap(HYPERVISOR_shared_info, PAGE_SIZE);
        HYPERVISOR_shared_info = __va(PFN_PHYS(shared_info_pfn));

        /*
         * The virtual address of the shared_info page has changed, so
         * the vcpu_info pointer for VCPU 0 is now stale.
         *
         * The prepare_boot_cpu callback will re-initialize it via
         * xen_vcpu_setup, but we can't rely on that to be called for
         * old Xen versions (xen_have_vector_callback == 0).
         *
         * It is, in any case, bad to have a stale vcpu_info pointer
         * so reset it now.
         */
        xen_vcpu_info_reset(0);
}

static void __init init_hvm_pv_info(void)
{
        int major, minor;
        uint32_t eax, ebx, ecx, edx, base;

        base = xen_cpuid_base();
        eax = cpuid_eax(base + 1);

        major = eax >> 16;
        minor = eax & 0xffff;
        printk(KERN_INFO "Xen version %d.%d.\n", major, minor);

        xen_domain_type = XEN_HVM_DOMAIN;

        /* PVH set up hypercall page in xen_prepare_pvh(). */
        if (xen_pvh_domain())
                pv_info.name = "Xen PVH";
        else {
                u64 pfn;
                uint32_t msr;

                pv_info.name = "Xen HVM";
                msr = cpuid_ebx(base + 2);
                pfn = __pa(hypercall_page);
                wrmsr_safe(msr, (u32)pfn, (u32)(pfn >> 32));
        }

        xen_setup_features();

        cpuid(base + 4, &eax, &ebx, &ecx, &edx);
        if (eax & XEN_HVM_CPUID_VCPU_ID_PRESENT)
                this_cpu_write(xen_vcpu_id, ebx);
        else
                this_cpu_write(xen_vcpu_id, smp_processor_id());
}

DEFINE_IDTENTRY_SYSVEC(sysvec_xen_hvm_callback)
{
        struct pt_regs *old_regs = set_irq_regs(regs);

        inc_irq_stat(irq_hv_callback_count);

        xen_hvm_evtchn_do_upcall();

        set_irq_regs(old_regs);
}

#ifdef CONFIG_KEXEC_CORE
static void xen_hvm_shutdown(void)
{
        native_machine_shutdown();
        if (kexec_in_progress)
                xen_reboot(SHUTDOWN_soft_reset);
}

static void xen_hvm_crash_shutdown(struct pt_regs *regs)
{
        native_machine_crash_shutdown(regs);
        xen_reboot(SHUTDOWN_soft_reset);
}
#endif

static int xen_cpu_up_prepare_hvm(unsigned int cpu)
{
        int rc = 0;

        /*
         * This can happen if CPU was offlined earlier and
         * offlining timed out in common_cpu_die().
         */
        if (cpu_report_state(cpu) == CPU_DEAD_FROZEN) {
                xen_smp_intr_free(cpu);
                xen_uninit_lock_cpu(cpu);
        }

        if (cpu_acpi_id(cpu) != U32_MAX)
                per_cpu(xen_vcpu_id, cpu) = cpu_acpi_id(cpu);
        else
                per_cpu(xen_vcpu_id, cpu) = cpu;
        rc = xen_vcpu_setup(cpu);
        if (rc || !xen_have_vector_callback)
                return rc;

        if (xen_feature(XENFEAT_hvm_safe_pvclock))
                xen_setup_timer(cpu);

        rc = xen_smp_intr_init(cpu);
        if (rc) {
                WARN(1, "xen_smp_intr_init() for CPU %d failed: %d\n",
                     cpu, rc);
        }
        return rc;
}

static int xen_cpu_dead_hvm(unsigned int cpu)
{
        xen_smp_intr_free(cpu);

        if (xen_have_vector_callback && xen_feature(XENFEAT_hvm_safe_pvclock))
                xen_teardown_timer(cpu);

       return 0;
}

static bool no_vector_callback __initdata;

static void __init xen_hvm_guest_init(void)
{
        if (xen_pv_domain())
                return;

        init_hvm_pv_info();

        reserve_shared_info();
        xen_hvm_init_shared_info();

        /*
         * 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.
         */
        xen_vcpu_info_reset(0);

        xen_panic_handler_init();

        if (!no_vector_callback && xen_feature(XENFEAT_hvm_callback_vector))
                xen_have_vector_callback = 1;

        xen_hvm_smp_init();
        WARN_ON(xen_cpuhp_setup(xen_cpu_up_prepare_hvm, xen_cpu_dead_hvm));
        xen_unplug_emulated_devices();
        x86_init.irqs.intr_init = xen_init_IRQ;
        xen_hvm_init_time_ops();
        xen_hvm_init_mmu_ops();

#ifdef CONFIG_KEXEC_CORE
        machine_ops.shutdown = xen_hvm_shutdown;
        machine_ops.crash_shutdown = xen_hvm_crash_shutdown;
#endif
}

static __init int xen_parse_nopv(char *arg)
{
        pr_notice("\"xen_nopv\" is deprecated, please use \"nopv\" instead\n");

        if (xen_cpuid_base())
                nopv = true;
        return 0;
}
early_param("xen_nopv", xen_parse_nopv);

static __init int xen_parse_no_vector_callback(char *arg)
{
        no_vector_callback = true;
        return 0;
}
early_param("xen_no_vector_callback", xen_parse_no_vector_callback);

bool __init xen_hvm_need_lapic(void)
{
        if (xen_pv_domain())
                return false;
        if (!xen_hvm_domain())
                return false;
        if (xen_feature(XENFEAT_hvm_pirqs) && xen_have_vector_callback)
                return false;
        return true;
}

static __init void xen_hvm_guest_late_init(void)
{
#ifdef CONFIG_XEN_PVH
        /* Test for PVH domain (PVH boot path taken overrides ACPI flags). */
        if (!xen_pvh &&
            (x86_platform.legacy.rtc || !x86_platform.legacy.no_vga))
                return;

        /* PVH detected. */
        xen_pvh = true;

        if (nopv)
                panic("\"nopv\" and \"xen_nopv\" parameters are unsupported in PVH guest.");

        /* Make sure we don't fall back to (default) ACPI_IRQ_MODEL_PIC. */
        if (!nr_ioapics && acpi_irq_model == ACPI_IRQ_MODEL_PIC)
                acpi_irq_model = ACPI_IRQ_MODEL_PLATFORM;

        machine_ops.emergency_restart = xen_emergency_restart;
        pv_info.name = "Xen PVH";
#endif
}

static uint32_t __init xen_platform_hvm(void)
{
        uint32_t xen_domain = xen_cpuid_base();
        struct x86_hyper_init *h = &x86_hyper_xen_hvm.init;

        if (xen_pv_domain())
                return 0;

        if (xen_pvh_domain() && nopv) {
                /* Guest booting via the Xen-PVH boot entry goes here */
                pr_info("\"nopv\" parameter is ignored in PVH guest\n");
                nopv = false;
        } else if (nopv && xen_domain) {
                /*
                 * Guest booting via normal boot entry (like via grub2) goes
                 * here.
                 *
                 * Use interface functions for bare hardware if nopv,
                 * xen_hvm_guest_late_init is an exception as we need to
                 * detect PVH and panic there.
                 */
                h->init_platform = x86_init_noop;
                h->x2apic_available = bool_x86_init_noop;
                h->init_mem_mapping = x86_init_noop;
                h->init_after_bootmem = x86_init_noop;
                h->guest_late_init = xen_hvm_guest_late_init;
                x86_hyper_xen_hvm.runtime.pin_vcpu = x86_op_int_noop;
        }
        return xen_domain;
}

struct hypervisor_x86 x86_hyper_xen_hvm __initdata = {
        .name                   = "Xen HVM",
        .detect                 = xen_platform_hvm,
        .type                   = X86_HYPER_XEN_HVM,
        .init.init_platform     = xen_hvm_guest_init,
        .init.x2apic_available  = xen_x2apic_para_available,
        .init.init_mem_mapping  = xen_hvm_init_mem_mapping,
        .init.guest_late_init   = xen_hvm_guest_late_init,
        .runtime.pin_vcpu       = xen_pin_vcpu,
        .ignore_nopv            = true,
};