/*
 * Copyright (c) 2014 Roger Pau Monné <roger.pau@citrix.com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/proc.h>
#include <sys/smp.h>
#include <sys/systm.h>

#include <vm/vm.h>
#include <vm/pmap.h>

#include <machine/cpufunc.h>
#include <machine/cpu.h>
#include <machine/intr_machdep.h>
#include <machine/md_var.h>
#include <machine/smp.h>

#include <x86/apicreg.h>
#include <x86/apicvar.h>

#include <xen/xen-os.h>
#include <xen/features.h>
#include <xen/gnttab.h>
#include <xen/hypervisor.h>
#include <xen/hvm.h>
#include <xen/xen_intr.h>

#include <contrib/xen/arch-x86/cpuid.h>
#include <contrib/xen/vcpu.h>

/*--------------------------- Forward Declarations ---------------------------*/
static driver_filter_t xen_smp_rendezvous_action;
#ifdef __amd64__
static driver_filter_t xen_invlop;
#else
static driver_filter_t xen_invltlb;
static driver_filter_t xen_invlpg;
static driver_filter_t xen_invlrng;
static driver_filter_t xen_invlcache;
#endif
static driver_filter_t xen_ipi_bitmap_handler;
static driver_filter_t xen_cpustop_handler;
static driver_filter_t xen_cpususpend_handler;
static driver_filter_t xen_ipi_swi_handler;

/*---------------------------------- Macros ----------------------------------*/
#define IPI_TO_IDX(ipi) ((ipi) - APIC_IPI_INTS)

/*--------------------------------- Xen IPIs ---------------------------------*/
struct xen_ipi_handler
{
        driver_filter_t *filter;
        const char      *description;
};

static struct xen_ipi_handler xen_ipis[] = 
{
        [IPI_TO_IDX(IPI_RENDEZVOUS)]    = { xen_smp_rendezvous_action,  "r"   },
#ifdef __amd64__
        [IPI_TO_IDX(IPI_INVLOP)]        = { xen_invlop,                 "itlb"},
#else
        [IPI_TO_IDX(IPI_INVLTLB)]       = { xen_invltlb,                "itlb"},
        [IPI_TO_IDX(IPI_INVLPG)]        = { xen_invlpg,                 "ipg" },
        [IPI_TO_IDX(IPI_INVLRNG)]       = { xen_invlrng,                "irg" },
        [IPI_TO_IDX(IPI_INVLCACHE)]     = { xen_invlcache,              "ic"  },
#endif
        [IPI_TO_IDX(IPI_BITMAP_VECTOR)] = { xen_ipi_bitmap_handler,     "b"   },
        [IPI_TO_IDX(IPI_STOP)]          = { xen_cpustop_handler,        "st"  },
        [IPI_TO_IDX(IPI_SUSPEND)]       = { xen_cpususpend_handler,     "sp"  },
        [IPI_TO_IDX(IPI_SWI)]           = { xen_ipi_swi_handler,        "sw"  },
};

/*
 * Save previous (native) handler as a fallback. Xen < 4.7 doesn't support
 * VCPUOP_send_nmi for HVM guests, and thus we need a fallback in that case:
 *
 * https://lists.freebsd.org/archives/freebsd-xen/2022-January/000032.html
 */
void (*native_ipi_vectored)(u_int, int);

/*------------------------------- Per-CPU Data -------------------------------*/
DPCPU_DEFINE(xen_intr_handle_t, ipi_handle[nitems(xen_ipis)]);

/*------------------------------- Xen PV APIC --------------------------------*/

#define PCPU_ID_GET(id, field) (pcpu_find(id)->pc_##field)
static int
send_nmi(int dest)
{
        unsigned int cpu;
        int rc = 0;

        /*
         * NMIs are not routed over event channels, and instead delivered as on
         * native using the exception vector (#2). Triggering them can be done
         * using the local APIC, or an hypercall as a shortcut like it's done
         * below.
         */
        switch(dest) {
        case APIC_IPI_DEST_SELF:
                rc = HYPERVISOR_vcpu_op(VCPUOP_send_nmi, PCPU_GET(vcpu_id), NULL);
                break;
        case APIC_IPI_DEST_ALL:
                CPU_FOREACH(cpu) {
                        rc = HYPERVISOR_vcpu_op(VCPUOP_send_nmi,
                            PCPU_ID_GET(cpu, vcpu_id), NULL);
                        if (rc != 0)
                                break;
                }
                break;
        case APIC_IPI_DEST_OTHERS:
                CPU_FOREACH(cpu) {
                        if (cpu != PCPU_GET(cpuid)) {
                                rc = HYPERVISOR_vcpu_op(VCPUOP_send_nmi,
                                    PCPU_ID_GET(cpu, vcpu_id), NULL);
                                if (rc != 0)
                                        break;
                        }
                }
                break;
        default:
                rc = HYPERVISOR_vcpu_op(VCPUOP_send_nmi,
                    PCPU_ID_GET(apic_cpuid(dest), vcpu_id), NULL);
                break;
        }

        return rc;
}
#undef PCPU_ID_GET

static void
xen_pv_lapic_ipi_vectored(u_int vector, int dest)
{
        xen_intr_handle_t *ipi_handle;
        int ipi_idx, to_cpu, self;
        static bool pvnmi = true;

        if (vector >= IPI_NMI_FIRST) {
                if (pvnmi) {
                        int rc = send_nmi(dest);

                        if (rc != 0) {
                                printf(
    "Sending NMI using hypercall failed (%d) switching to APIC\n", rc);
                                pvnmi = false;
                                native_ipi_vectored(vector, dest);
                        }
                } else
                        native_ipi_vectored(vector, dest);

                return;
        }

        ipi_idx = IPI_TO_IDX(vector);
        if (ipi_idx >= nitems(xen_ipis))
                panic("IPI out of range");

        switch(dest) {
        case APIC_IPI_DEST_SELF:
                ipi_handle = DPCPU_GET(ipi_handle);
                xen_intr_signal(ipi_handle[ipi_idx]);
                break;
        case APIC_IPI_DEST_ALL:
                CPU_FOREACH(to_cpu) {
                        ipi_handle = DPCPU_ID_GET(to_cpu, ipi_handle);
                        xen_intr_signal(ipi_handle[ipi_idx]);
                }
                break;
        case APIC_IPI_DEST_OTHERS:
                self = PCPU_GET(cpuid);
                CPU_FOREACH(to_cpu) {
                        if (to_cpu != self) {
                                ipi_handle = DPCPU_ID_GET(to_cpu, ipi_handle);
                                xen_intr_signal(ipi_handle[ipi_idx]);
                        }
                }
                break;
        default:
                to_cpu = apic_cpuid(dest);
                ipi_handle = DPCPU_ID_GET(to_cpu, ipi_handle);
                xen_intr_signal(ipi_handle[ipi_idx]);
                break;
        }
}

/*---------------------------- XEN PV IPI Handlers ---------------------------*/
/*
 * These are C clones of the ASM functions found in apic_vector.
 */
static int
xen_ipi_bitmap_handler(void *arg)
{

        ipi_bitmap_handler(curthread->td_intr_frame);
        return (FILTER_HANDLED);
}

static int
xen_smp_rendezvous_action(void *arg)
{
#ifdef COUNT_IPIS
        (*ipi_rendezvous_counts[PCPU_GET(cpuid)])++;
#endif /* COUNT_IPIS */

        smp_rendezvous_action();
        return (FILTER_HANDLED);
}

#ifdef __amd64__
static int
xen_invlop(void *arg)
{

        invlop_handler();
        return (FILTER_HANDLED);
}

#else /* __i386__ */

static int
xen_invltlb(void *arg)
{

        invltlb_handler();
        return (FILTER_HANDLED);
}

static int
xen_invlpg(void *arg)
{

        invlpg_handler();
        return (FILTER_HANDLED);
}

static int
xen_invlrng(void *arg)
{

        invlrng_handler();
        return (FILTER_HANDLED);
}

static int
xen_invlcache(void *arg)
{

        invlcache_handler();
        return (FILTER_HANDLED);
}
#endif /* __amd64__ */

static int
xen_cpustop_handler(void *arg)
{

        cpustop_handler();
        return (FILTER_HANDLED);
}

static int
xen_cpususpend_handler(void *arg)
{

        cpususpend_handler();
        return (FILTER_HANDLED);
}

static int
xen_ipi_swi_handler(void *arg)
{

        ipi_swi_handler(curthread->td_intr_frame);
        return (FILTER_HANDLED);
}

/*----------------------------- XEN PV IPI setup -----------------------------*/
/*
 * Those functions are provided outside of the Xen PV APIC implementation
 * so PVHVM guests can also use PV IPIs without having an actual Xen PV APIC,
 * because on PVHVM there's an emulated LAPIC provided by Xen.
 */
static void
xen_cpu_ipi_init(int cpu)
{
        xen_intr_handle_t *ipi_handle;
        const struct xen_ipi_handler *ipi;
        int idx, rc;

        ipi_handle = DPCPU_ID_GET(cpu, ipi_handle);

        for (ipi = xen_ipis, idx = 0; idx < nitems(xen_ipis); ipi++, idx++) {
                if (ipi->filter == NULL) {
                        ipi_handle[idx] = NULL;
                        continue;
                }

                rc = xen_intr_alloc_and_bind_ipi(cpu, ipi->filter,
                    INTR_TYPE_TTY, &ipi_handle[idx]);
                if (rc != 0)
                        panic("Unable to allocate a XEN IPI port");
                xen_intr_describe(ipi_handle[idx], "%s", ipi->description);
        }
}

static void
xen_setup_cpus(void *dummy __unused)
{
        uint32_t regs[4];
        int i;

        if (!xen_vector_callback_enabled)
                return;

        /*
         * Check whether the APIC virtualization is hardware assisted, as
         * that's faster than using event channels because it avoids the VM
         * exit.
         */
        KASSERT(hv_base != 0, ("Invalid base Xen CPUID leaf"));
        cpuid_count(hv_base + 4, 0, regs);
        if ((x2apic_mode && (regs[0] & XEN_HVM_CPUID_X2APIC_VIRT)) ||
            (!x2apic_mode && (regs[0] & XEN_HVM_CPUID_APIC_ACCESS_VIRT)))
                return;

        CPU_FOREACH(i)
                xen_cpu_ipi_init(i);

        /* Set the xen pv ipi ops to replace the native ones */
        ipi_vectored = xen_pv_lapic_ipi_vectored;
        native_ipi_vectored = ipi_vectored;
}

/* Switch to using PV IPIs as soon as the vcpu_id is set. */
SYSINIT(xen_setup_cpus, SI_SUB_SMP, SI_ORDER_SECOND, xen_setup_cpus, NULL);