/*-
 * Copyright (c) 2009-2012,2016-2017 Microsoft Corp.
 * Copyright (c) 2012 NetApp Inc.
 * Copyright (c) 2012 Citrix Inc.
 * 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 unmodified, 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 ``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 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.
 */

/*
 * VM Bus Driver Implementation
 */

#include <sys/param.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/linker.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/sbuf.h>
#include <sys/smp.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/taskqueue.h>

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

#include <machine/bus.h>
#if defined(__aarch64__)
#include <dev/psci/smccc.h>
#include <dev/hyperv/vmbus/aarch64/hyperv_machdep.h>
#include <dev/hyperv/vmbus/aarch64/hyperv_reg.h>
#else
#include <dev/hyperv/vmbus/x86/hyperv_machdep.h>
#include <dev/hyperv/vmbus/x86/hyperv_reg.h>
#include <machine/intr_machdep.h>
#include <x86/include/apicvar.h>
#endif
#include <machine/metadata.h>
#include <machine/md_var.h>
#include <machine/resource.h>
#include <contrib/dev/acpica/include/acpi.h>
#include <dev/acpica/acpivar.h>

#include <dev/hyperv/include/hyperv.h>
#include <dev/hyperv/include/vmbus_xact.h>
#include <dev/hyperv/vmbus/hyperv_var.h>
#include <dev/hyperv/vmbus/vmbus_reg.h>
#include <dev/hyperv/vmbus/vmbus_var.h>
#include <dev/hyperv/vmbus/vmbus_chanvar.h>
#include <dev/hyperv/vmbus/hyperv_common_reg.h>
#include "acpi_if.h"
#include "pcib_if.h"
#include "vmbus_if.h"

#define VMBUS_GPADL_START               0xe1e10

struct vmbus_msghc {
        struct vmbus_xact               *mh_xact;
        struct hypercall_postmsg_in     mh_inprm_save;
};

static void                     vmbus_identify(driver_t *, device_t);
static int                      vmbus_probe(device_t);
static int                      vmbus_attach(device_t);
static int                      vmbus_detach(device_t);
static int                      vmbus_read_ivar(device_t, device_t, int,
                                    uintptr_t *);
static int                      vmbus_child_pnpinfo(device_t, device_t, struct sbuf *);
static struct resource          *vmbus_alloc_resource(device_t dev,
                                    device_t child, int type, int rid,
                                    rman_res_t start, rman_res_t end,
                                    rman_res_t count, u_int flags);
static int                      vmbus_alloc_msi(device_t bus, device_t dev,
                                    int count, int maxcount, int *irqs);
static int                      vmbus_release_msi(device_t bus, device_t dev,
                                    int count, int *irqs);
static int                      vmbus_alloc_msix(device_t bus, device_t dev,
                                    int *irq);
static int                      vmbus_release_msix(device_t bus, device_t dev,
                                    int irq);
static int                      vmbus_map_msi(device_t bus, device_t dev,
                                    int irq, uint64_t *addr, uint32_t *data);
static uint32_t                 vmbus_get_version_method(device_t, device_t);
static int                      vmbus_probe_guid_method(device_t, device_t,
                                    const struct hyperv_guid *);
static uint32_t                 vmbus_get_vcpu_id_method(device_t bus,
                                    device_t dev, int cpu);
static struct taskqueue         *vmbus_get_eventtq_method(device_t, device_t,
                                    int);
#if defined(EARLY_AP_STARTUP)
static void                     vmbus_intrhook(void *);
#endif

static int                      vmbus_init(struct vmbus_softc *);
static int                      vmbus_connect(struct vmbus_softc *, uint32_t);
static int                      vmbus_req_channels(struct vmbus_softc *sc);
static void                     vmbus_disconnect(struct vmbus_softc *);
static int                      vmbus_scan(struct vmbus_softc *);
static void                     vmbus_scan_teardown(struct vmbus_softc *);
static void                     vmbus_scan_done(struct vmbus_softc *,
                                    const struct vmbus_message *);
static void                     vmbus_chanmsg_handle(struct vmbus_softc *,
                                    const struct vmbus_message *);
static void                     vmbus_msg_task(void *, int);
static void                     vmbus_synic_setup(void *);
static void                     vmbus_synic_teardown(void *);
static int                      vmbus_sysctl_version(SYSCTL_HANDLER_ARGS);
static int                      vmbus_dma_alloc(struct vmbus_softc *);
static void                     vmbus_dma_free(struct vmbus_softc *);
static int                      vmbus_intr_setup(struct vmbus_softc *);
static void                     vmbus_intr_teardown(struct vmbus_softc *);
static int                      vmbus_doattach(struct vmbus_softc *);
static void                     vmbus_event_proc_dummy(struct vmbus_softc *,
                                    int);
static bus_dma_tag_t    vmbus_get_dma_tag(device_t parent, device_t child);
static struct vmbus_softc       *vmbus_sc;
#if defined(__x86_64__)
static int vmbus_alloc_cpu_mem(struct vmbus_softc *sc);
static void vmbus_free_cpu_mem(struct vmbus_softc *sc);
#endif

SYSCTL_NODE(_hw, OID_AUTO, vmbus, CTLFLAG_RD | CTLFLAG_MPSAFE, NULL,
    "Hyper-V vmbus");

static int                      vmbus_pin_evttask = 1;
SYSCTL_INT(_hw_vmbus, OID_AUTO, pin_evttask, CTLFLAG_RDTUN,
    &vmbus_pin_evttask, 0, "Pin event tasks to their respective CPU");

#if defined(__x86_64__)
static int                      hv_tlb_hcall = 1;
SYSCTL_INT(_hw_vmbus, OID_AUTO, tlb_hcall , CTLFLAG_RDTUN,
    &hv_tlb_hcall, 0, "Use Hyper_V hyercall for tlb flush");
#endif

uint32_t                        vmbus_current_version;

static const uint32_t           vmbus_version[] = {
        VMBUS_VERSION_WIN10,
        VMBUS_VERSION_WIN8_1,
        VMBUS_VERSION_WIN8,
        VMBUS_VERSION_WIN7,
        VMBUS_VERSION_WS2008
};

static const vmbus_chanmsg_proc_t
vmbus_chanmsg_handlers[VMBUS_CHANMSG_TYPE_MAX] = {
        VMBUS_CHANMSG_PROC(CHOFFER_DONE, vmbus_scan_done),
        VMBUS_CHANMSG_PROC_WAKEUP(CONNECT_RESP)
};

static device_method_t vmbus_methods[] = {
        /* Device interface */
        DEVMETHOD(device_identify,              vmbus_identify),
        DEVMETHOD(device_probe,                 vmbus_probe),
        DEVMETHOD(device_attach,                vmbus_attach),
        DEVMETHOD(device_detach,                vmbus_detach),
        DEVMETHOD(device_shutdown,              bus_generic_shutdown),
        DEVMETHOD(device_suspend,               bus_generic_suspend),
        DEVMETHOD(device_resume,                bus_generic_resume),

        /* Bus interface */
        DEVMETHOD(bus_add_child,                bus_generic_add_child),
        DEVMETHOD(bus_print_child,              bus_generic_print_child),
        DEVMETHOD(bus_read_ivar,                vmbus_read_ivar),
        DEVMETHOD(bus_child_pnpinfo,            vmbus_child_pnpinfo),
        DEVMETHOD(bus_alloc_resource,           vmbus_alloc_resource),
        DEVMETHOD(bus_release_resource,         bus_generic_release_resource),
        DEVMETHOD(bus_activate_resource,        bus_generic_activate_resource),
        DEVMETHOD(bus_deactivate_resource,      bus_generic_deactivate_resource),
        DEVMETHOD(bus_setup_intr,               bus_generic_setup_intr),
        DEVMETHOD(bus_teardown_intr,            bus_generic_teardown_intr),
        DEVMETHOD(bus_get_cpus,                 bus_generic_get_cpus),
        DEVMETHOD(bus_get_dma_tag,              vmbus_get_dma_tag),

        /* pcib interface */
        DEVMETHOD(pcib_alloc_msi,               vmbus_alloc_msi),
        DEVMETHOD(pcib_release_msi,             vmbus_release_msi),
        DEVMETHOD(pcib_alloc_msix,              vmbus_alloc_msix),
        DEVMETHOD(pcib_release_msix,            vmbus_release_msix),
        DEVMETHOD(pcib_map_msi,                 vmbus_map_msi),

        /* Vmbus interface */
        DEVMETHOD(vmbus_get_version,            vmbus_get_version_method),
        DEVMETHOD(vmbus_probe_guid,             vmbus_probe_guid_method),
        DEVMETHOD(vmbus_get_vcpu_id,            vmbus_get_vcpu_id_method),
        DEVMETHOD(vmbus_get_event_taskq,        vmbus_get_eventtq_method),

        DEVMETHOD_END
};

static driver_t vmbus_driver = {
        "vmbus",
        vmbus_methods,
        sizeof(struct vmbus_softc)
};

uint32_t hv_max_vp_index;

DRIVER_MODULE(vmbus, pcib, vmbus_driver, NULL, NULL);
DRIVER_MODULE(vmbus, acpi_syscontainer, vmbus_driver, NULL, NULL);

MODULE_DEPEND(vmbus, acpi, 1, 1, 1);
MODULE_DEPEND(vmbus, pci, 1, 1, 1);
MODULE_VERSION(vmbus, 1);

static __inline struct vmbus_softc *
vmbus_get_softc(void)
{
        return vmbus_sc;
}

static bus_dma_tag_t
vmbus_get_dma_tag(device_t dev, device_t child)
{
        struct vmbus_softc *sc = vmbus_get_softc();
        return (sc->dmat);
}

void
vmbus_msghc_reset(struct vmbus_msghc *mh, size_t dsize)
{
        struct hypercall_postmsg_in *inprm;

        if (dsize > HYPERCALL_POSTMSGIN_DSIZE_MAX)
                panic("invalid data size %zu", dsize);

        inprm = vmbus_xact_req_data(mh->mh_xact);
        memset(inprm, 0, HYPERCALL_POSTMSGIN_SIZE);
        inprm->hc_connid = VMBUS_CONNID_MESSAGE;
        inprm->hc_msgtype = HYPERV_MSGTYPE_CHANNEL;
        inprm->hc_dsize = dsize;
}

struct vmbus_msghc *
vmbus_msghc_get(struct vmbus_softc *sc, size_t dsize)
{
        struct vmbus_msghc *mh;
        struct vmbus_xact *xact;

        if (dsize > HYPERCALL_POSTMSGIN_DSIZE_MAX)
                panic("invalid data size %zu", dsize);

        xact = vmbus_xact_get(sc->vmbus_xc,
            dsize + __offsetof(struct hypercall_postmsg_in, hc_data[0]));
        if (xact == NULL)
                return (NULL);

        mh = vmbus_xact_priv(xact, sizeof(*mh));
        mh->mh_xact = xact;

        vmbus_msghc_reset(mh, dsize);
        return (mh);
}

void
vmbus_msghc_put(struct vmbus_softc *sc __unused, struct vmbus_msghc *mh)
{

        vmbus_xact_put(mh->mh_xact);
}

void *
vmbus_msghc_dataptr(struct vmbus_msghc *mh)
{
        struct hypercall_postmsg_in *inprm;

        inprm = vmbus_xact_req_data(mh->mh_xact);
        return (inprm->hc_data);
}

int
vmbus_msghc_exec_noresult(struct vmbus_msghc *mh)
{
        sbintime_t time = SBT_1MS;
        struct hypercall_postmsg_in *inprm;
        bus_addr_t inprm_paddr;
        int i;

        inprm = vmbus_xact_req_data(mh->mh_xact);
        inprm_paddr = vmbus_xact_req_paddr(mh->mh_xact);

        /*
         * Save the input parameter so that we could restore the input
         * parameter if the Hypercall failed.
         *
         * XXX
         * Is this really necessary?!  i.e. Will the Hypercall ever
         * overwrite the input parameter?
         */
        memcpy(&mh->mh_inprm_save, inprm, HYPERCALL_POSTMSGIN_SIZE);

        /*
         * In order to cope with transient failures, e.g. insufficient
         * resources on host side, we retry the post message Hypercall
         * several times.  20 retries seem sufficient.
         */
#define HC_RETRY_MAX    20

        for (i = 0; i < HC_RETRY_MAX; ++i) {
                uint64_t status;

                status = hypercall_post_message(inprm_paddr);
                if (status == HYPERCALL_STATUS_SUCCESS)
                        return 0;

                pause_sbt("hcpmsg", time, 0, C_HARDCLOCK);
                if (time < SBT_1S * 2)
                        time *= 2;

                /* Restore input parameter and try again */
                memcpy(inprm, &mh->mh_inprm_save, HYPERCALL_POSTMSGIN_SIZE);
        }

#undef HC_RETRY_MAX

        return EIO;
}

int
vmbus_msghc_exec(struct vmbus_softc *sc __unused, struct vmbus_msghc *mh)
{
        int error;

        vmbus_xact_activate(mh->mh_xact);
        error = vmbus_msghc_exec_noresult(mh);
        if (error)
                vmbus_xact_deactivate(mh->mh_xact);
        return error;
}

void
vmbus_msghc_exec_cancel(struct vmbus_softc *sc __unused, struct vmbus_msghc *mh)
{

        vmbus_xact_deactivate(mh->mh_xact);
}

const struct vmbus_message *
vmbus_msghc_wait_result(struct vmbus_softc *sc __unused, struct vmbus_msghc *mh)
{
        size_t resp_len;

        return (vmbus_xact_wait(mh->mh_xact, &resp_len));
}

const struct vmbus_message *
vmbus_msghc_poll_result(struct vmbus_softc *sc __unused, struct vmbus_msghc *mh)
{
        size_t resp_len;

        return (vmbus_xact_poll(mh->mh_xact, &resp_len));
}

void
vmbus_msghc_wakeup(struct vmbus_softc *sc, const struct vmbus_message *msg)
{

        vmbus_xact_ctx_wakeup(sc->vmbus_xc, msg, sizeof(*msg));
}

uint32_t
vmbus_gpadl_alloc(struct vmbus_softc *sc)
{
        uint32_t gpadl;

again:
        gpadl = atomic_fetchadd_int(&sc->vmbus_gpadl, 1);
        if (gpadl == 0)
                goto again;
        return (gpadl);
}

/* Used for Hyper-V socket when guest client connects to host */
int
vmbus_req_tl_connect(struct hyperv_guid *guest_srv_id,
    struct hyperv_guid *host_srv_id)
{
        struct vmbus_softc *sc = vmbus_get_softc();
        struct vmbus_chanmsg_tl_connect *req;
        struct vmbus_msghc *mh;
        int error;

        if (!sc)
                return ENXIO;

        mh = vmbus_msghc_get(sc, sizeof(*req));
        if (mh == NULL) {
                device_printf(sc->vmbus_dev,
                    "can not get msg hypercall for tl connect\n");
                return ENXIO;
        }

        req = vmbus_msghc_dataptr(mh);
        req->chm_hdr.chm_type = VMBUS_CHANMSG_TYPE_TL_CONN;
        req->guest_endpoint_id = *guest_srv_id;
        req->host_service_id = *host_srv_id;

        error = vmbus_msghc_exec_noresult(mh);
        vmbus_msghc_put(sc, mh);

        if (error) {
                device_printf(sc->vmbus_dev,
                    "tl connect msg hypercall failed\n");
        }

        return error;
}

static int
vmbus_connect(struct vmbus_softc *sc, uint32_t version)
{
        struct vmbus_chanmsg_connect *req;
        const struct vmbus_message *msg;
        struct vmbus_msghc *mh;
        int error, done = 0;

        mh = vmbus_msghc_get(sc, sizeof(*req));
        if (mh == NULL)
                return ENXIO;

        req = vmbus_msghc_dataptr(mh);
        req->chm_hdr.chm_type = VMBUS_CHANMSG_TYPE_CONNECT;
        req->chm_ver = version;
        req->chm_evtflags = pmap_kextract((vm_offset_t)sc->vmbus_evtflags);
        req->chm_mnf1 = pmap_kextract((vm_offset_t)sc->vmbus_mnf1);
        req->chm_mnf2 = pmap_kextract((vm_offset_t)sc->vmbus_mnf2);

        error = vmbus_msghc_exec(sc, mh);
        if (error) {
                vmbus_msghc_put(sc, mh);
                return error;
        }

        msg = vmbus_msghc_wait_result(sc, mh);
        done = ((const struct vmbus_chanmsg_connect_resp *)
            msg->msg_data)->chm_done;

        vmbus_msghc_put(sc, mh);

        return (done ? 0 : EOPNOTSUPP);
}

static int
vmbus_init(struct vmbus_softc *sc)
{
        int i;

        for (i = 0; i < nitems(vmbus_version); ++i) {
                int error;

                error = vmbus_connect(sc, vmbus_version[i]);
                if (!error) {
                        vmbus_current_version = vmbus_version[i];
                        sc->vmbus_version = vmbus_version[i];
                        device_printf(sc->vmbus_dev, "version %u.%u\n",
                            VMBUS_VERSION_MAJOR(sc->vmbus_version),
                            VMBUS_VERSION_MINOR(sc->vmbus_version));
                        return 0;
                }
        }
        return ENXIO;
}

static void
vmbus_disconnect(struct vmbus_softc *sc)
{
        struct vmbus_chanmsg_disconnect *req;
        struct vmbus_msghc *mh;
        int error;

        mh = vmbus_msghc_get(sc, sizeof(*req));
        if (mh == NULL) {
                device_printf(sc->vmbus_dev,
                    "can not get msg hypercall for disconnect\n");
                return;
        }

        req = vmbus_msghc_dataptr(mh);
        req->chm_hdr.chm_type = VMBUS_CHANMSG_TYPE_DISCONNECT;

        error = vmbus_msghc_exec_noresult(mh);
        vmbus_msghc_put(sc, mh);

        if (error) {
                device_printf(sc->vmbus_dev,
                    "disconnect msg hypercall failed\n");
        }
}

static int
vmbus_req_channels(struct vmbus_softc *sc)
{
        struct vmbus_chanmsg_chrequest *req;
        struct vmbus_msghc *mh;
        int error;

        mh = vmbus_msghc_get(sc, sizeof(*req));
        if (mh == NULL)
                return ENXIO;

        req = vmbus_msghc_dataptr(mh);
        req->chm_hdr.chm_type = VMBUS_CHANMSG_TYPE_CHREQUEST;

        error = vmbus_msghc_exec_noresult(mh);
        vmbus_msghc_put(sc, mh);

        return error;
}

static void
vmbus_scan_done_task(void *xsc, int pending __unused)
{
        struct vmbus_softc *sc = xsc;

        bus_topo_lock();
        sc->vmbus_scandone = true;
        bus_topo_unlock();
        wakeup(&sc->vmbus_scandone);
}

static void
vmbus_scan_done(struct vmbus_softc *sc,
    const struct vmbus_message *msg __unused)
{

        taskqueue_enqueue(sc->vmbus_devtq, &sc->vmbus_scandone_task);
}

static int
vmbus_scan(struct vmbus_softc *sc)
{
        int error;

        /*
         * Identify, probe and attach for non-channel devices.
         */
        bus_identify_children(sc->vmbus_dev);
        bus_attach_children(sc->vmbus_dev);

        /*
         * This taskqueue serializes vmbus devices' attach and detach
         * for channel offer and rescind messages.
         */
        sc->vmbus_devtq = taskqueue_create("vmbus dev", M_WAITOK,
            taskqueue_thread_enqueue, &sc->vmbus_devtq);
        taskqueue_start_threads(&sc->vmbus_devtq, 1, PI_NET, "vmbusdev");
        TASK_INIT(&sc->vmbus_scandone_task, 0, vmbus_scan_done_task, sc);

        /*
         * This taskqueue handles sub-channel detach, so that vmbus
         * device's detach running in vmbus_devtq can drain its sub-
         * channels.
         */
        sc->vmbus_subchtq = taskqueue_create("vmbus subch", M_WAITOK,
            taskqueue_thread_enqueue, &sc->vmbus_subchtq);
        taskqueue_start_threads(&sc->vmbus_subchtq, 1, PI_NET, "vmbussch");

        /*
         * Start vmbus scanning.
         */
        error = vmbus_req_channels(sc);
        if (error) {
                device_printf(sc->vmbus_dev, "channel request failed: %d\n",
                    error);
                return (error);
        }

        /*
         * Wait for all vmbus devices from the initial channel offers to be
         * attached.
         */
        bus_topo_assert();
        while (!sc->vmbus_scandone)
                mtx_sleep(&sc->vmbus_scandone, bus_topo_mtx(), 0, "vmbusdev", 0);

        if (bootverbose) {
                device_printf(sc->vmbus_dev, "device scan, probe and attach "
                    "done\n");
        }
        return (0);
}

static void
vmbus_scan_teardown(struct vmbus_softc *sc)
{

        bus_topo_assert();
        if (sc->vmbus_devtq != NULL) {
                bus_topo_unlock();
                taskqueue_free(sc->vmbus_devtq);
                bus_topo_lock();
                sc->vmbus_devtq = NULL;
        }
        if (sc->vmbus_subchtq != NULL) {
                bus_topo_unlock();
                taskqueue_free(sc->vmbus_subchtq);
                bus_topo_lock();
                sc->vmbus_subchtq = NULL;
        }
}

static void
vmbus_chanmsg_handle(struct vmbus_softc *sc, const struct vmbus_message *msg)
{
        vmbus_chanmsg_proc_t msg_proc;
        uint32_t msg_type;

        msg_type = ((const struct vmbus_chanmsg_hdr *)msg->msg_data)->chm_type;
        if (msg_type >= VMBUS_CHANMSG_TYPE_MAX) {
                device_printf(sc->vmbus_dev, "unknown message type 0x%x\n",
                    msg_type);
                return;
        }

        msg_proc = vmbus_chanmsg_handlers[msg_type];
        if (msg_proc != NULL)
                msg_proc(sc, msg);

        /* Channel specific processing */
        vmbus_chan_msgproc(sc, msg);
}

static void
vmbus_msg_task(void *xsc, int pending __unused)
{
        struct vmbus_softc *sc = xsc;
        volatile struct vmbus_message *msg;

        msg = VMBUS_PCPU_GET(sc, message, curcpu) + VMBUS_SINT_MESSAGE;
        for (;;) {
                if (msg->msg_type == HYPERV_MSGTYPE_NONE) {
                        /* No message */
                        break;
                } else if (msg->msg_type == HYPERV_MSGTYPE_CHANNEL) {
                        /* Channel message */
                        vmbus_chanmsg_handle(sc,
                            __DEVOLATILE(const struct vmbus_message *, msg));
                }

                msg->msg_type = HYPERV_MSGTYPE_NONE;
                /*
                 * Make sure the write to msg_type (i.e. set to
                 * HYPERV_MSGTYPE_NONE) happens before we read the
                 * msg_flags and EOMing. Otherwise, the EOMing will
                 * not deliver any more messages since there is no
                 * empty slot
                 *
                 * NOTE:
                 * mb() is used here, since atomic_thread_fence_seq_cst()
                 * will become compiler fence on UP kernel.
                 */
                mb();
                if (msg->msg_flags & VMBUS_MSGFLAG_PENDING) {
                        /*
                         * This will cause message queue rescan to possibly
                         * deliver another msg from the hypervisor
                         */
                        WRMSR(MSR_HV_EOM, 0);
                }
        }
}
static __inline int
vmbus_handle_intr1(struct vmbus_softc *sc, struct trapframe *frame, int cpu)
{
        volatile struct vmbus_message *msg;
        struct vmbus_message *msg_base;

        msg_base = VMBUS_PCPU_GET(sc, message, cpu);

        /*
         * Check event timer.
         *
         * TODO: move this to independent IDT vector.
         */
        vmbus_handle_timer_intr1(msg_base, frame);
        /*
         * Check events.  Hot path for network and storage I/O data; high rate.
         *
         * NOTE:
         * As recommended by the Windows guest fellows, we check events before
         * checking messages.
         */
        sc->vmbus_event_proc(sc, cpu);

        /*
         * Check messages.  Mainly management stuffs; ultra low rate.
         */
        msg = msg_base + VMBUS_SINT_MESSAGE;
        if (__predict_false(msg->msg_type != HYPERV_MSGTYPE_NONE)) {
                taskqueue_enqueue(VMBUS_PCPU_GET(sc, message_tq, cpu),
                    VMBUS_PCPU_PTR(sc, message_task, cpu));
        }

        return (FILTER_HANDLED);
}

void
vmbus_handle_intr(struct trapframe *trap_frame)
{
        struct vmbus_softc *sc = vmbus_get_softc();
        int cpu = curcpu;

        /*
         * Disable preemption.
         */
        critical_enter();

        /*
         * Do a little interrupt counting. This used x86 specific
         * intrcnt_add function
         */
#if !defined(__aarch64__)
        (*VMBUS_PCPU_GET(sc, intr_cnt, cpu))++;
#endif /* not for aarch64 */
        vmbus_handle_intr1(sc, trap_frame, cpu);

        /*
         * Enable preemption.
         */
        critical_exit();
}

static void
vmbus_synic_setup(void *xsc)
{
        struct vmbus_softc *sc = xsc;
        int cpu = curcpu;
        uint64_t val, orig;
        uint32_t sint;

        if (hyperv_features & CPUID_HV_MSR_VP_INDEX) {
                /* Save virtual processor id. */
                VMBUS_PCPU_GET(sc, vcpuid, cpu) = RDMSR(MSR_HV_VP_INDEX);
        } else {
                /* Set virtual processor id to 0 for compatibility. */
                VMBUS_PCPU_GET(sc, vcpuid, cpu) = 0;
        }

        if (VMBUS_PCPU_GET(sc, vcpuid, cpu) > hv_max_vp_index)
                hv_max_vp_index = VMBUS_PCPU_GET(sc, vcpuid, cpu);

        /*
         * Setup the SynIC message.
         */
        orig = RDMSR(MSR_HV_SIMP);
        val = pmap_kextract((vm_offset_t)VMBUS_PCPU_GET(sc, message, cpu)) &
            MSR_HV_SIMP_PGMASK;
        val |= MSR_HV_SIMP_ENABLE | (orig & MSR_HV_SIMP_RSVD_MASK);
        WRMSR(MSR_HV_SIMP, val);
        /*
         * Setup the SynIC event flags.
         */
        orig = RDMSR(MSR_HV_SIEFP);
        val = pmap_kextract((vm_offset_t)VMBUS_PCPU_GET(sc, event_flags, cpu)) &
            MSR_HV_SIMP_PGMASK;
        val |= MSR_HV_SIEFP_ENABLE | (orig & MSR_HV_SIEFP_RSVD_MASK);
        WRMSR(MSR_HV_SIEFP, val);

        /*
         * Configure and unmask SINT for message and event flags.
         */
        sint = MSR_HV_SINT0 + VMBUS_SINT_MESSAGE;
        orig = RDMSR(sint);
        val = sc->vmbus_idtvec | MSR_HV_SINT_AUTOEOI |
            (orig & MSR_HV_SINT_RSVD_MASK);
        WRMSR(sint, val);

        /*
         * Configure and unmask SINT for timer.
         */
        vmbus_synic_setup1(sc);
        /*
         * All done; enable SynIC.
         */
        orig = RDMSR(MSR_HV_SCONTROL);
        val = MSR_HV_SCTRL_ENABLE | (orig & MSR_HV_SCTRL_RSVD_MASK);
        WRMSR(MSR_HV_SCONTROL, val);
}

#if defined(__x86_64__)
void
hyperv_vm_tlb_flush(pmap_t pmap, vm_offset_t addr1, vm_offset_t addr2,
    smp_invl_local_cb_t curcpu_cb, enum invl_op_codes op)
{
        struct vmbus_softc *sc = vmbus_get_softc();
        return hv_vm_tlb_flush(pmap, addr1, addr2, op, sc, curcpu_cb);
}
#endif /*__x86_64__*/

static void
vmbus_synic_teardown(void *arg)
{
        uint64_t orig;
        uint32_t sint;

        /*
         * Disable SynIC.
         */
        orig = RDMSR(MSR_HV_SCONTROL);
        WRMSR(MSR_HV_SCONTROL, (orig & MSR_HV_SCTRL_RSVD_MASK));

        /*
         * Mask message and event flags SINT.
         */
        sint = MSR_HV_SINT0 + VMBUS_SINT_MESSAGE;
        orig = RDMSR(sint);
        WRMSR(sint, orig | MSR_HV_SINT_MASKED);

        /*
         * Mask timer SINT.
         */
        vmbus_synic_teardown1();
        /*
         * Teardown SynIC message.
         */
        orig = RDMSR(MSR_HV_SIMP);
        WRMSR(MSR_HV_SIMP, (orig & MSR_HV_SIMP_RSVD_MASK));

        /*
         * Teardown SynIC event flags.
         */
        orig = RDMSR(MSR_HV_SIEFP);
        WRMSR(MSR_HV_SIEFP, (orig & MSR_HV_SIEFP_RSVD_MASK));
}

static int
vmbus_dma_alloc(struct vmbus_softc *sc)
{
        uint8_t *evtflags;
        int cpu;

        CPU_FOREACH(cpu) {
                void *ptr;

                /*
                 * Per-cpu messages and event flags.
                 */
                ptr = contigmalloc(PAGE_SIZE, M_DEVBUF, M_WAITOK | M_ZERO,
                    0ul, ~0ul, PAGE_SIZE, 0);
                if (ptr == NULL)
                        return ENOMEM;
                VMBUS_PCPU_GET(sc, message, cpu) = ptr;

                ptr = contigmalloc(PAGE_SIZE, M_DEVBUF, M_WAITOK | M_ZERO,
                    0ul, ~0ul, PAGE_SIZE, 0);
                if (ptr == NULL)
                        return ENOMEM;
                VMBUS_PCPU_GET(sc, event_flags, cpu) = ptr;
        }

        evtflags = contigmalloc(PAGE_SIZE, M_DEVBUF, M_WAITOK | M_ZERO,
            0ul, ~0ul, PAGE_SIZE, 0);
        if (evtflags == NULL)
                return ENOMEM;
        sc->vmbus_rx_evtflags = (u_long *)evtflags;
        sc->vmbus_tx_evtflags = (u_long *)(evtflags + (PAGE_SIZE / 2));
        sc->vmbus_evtflags = evtflags;

        sc->vmbus_mnf1 = contigmalloc(PAGE_SIZE, M_DEVBUF, M_WAITOK | M_ZERO,
            0ul, ~0ul, PAGE_SIZE, 0);
        if (sc->vmbus_mnf1 == NULL)
                return ENOMEM;

        sc->vmbus_mnf2 = contigmalloc(sizeof(struct vmbus_mnf), M_DEVBUF,
            M_WAITOK | M_ZERO, 0ul, ~0ul, PAGE_SIZE, 0);
        if (sc->vmbus_mnf2 == NULL)
                return ENOMEM;

        return 0;
}

static void
vmbus_dma_free(struct vmbus_softc *sc)
{
        int cpu;

        if (sc->vmbus_evtflags != NULL) {
                free(sc->vmbus_evtflags, M_DEVBUF);
                sc->vmbus_evtflags = NULL;
                sc->vmbus_rx_evtflags = NULL;
                sc->vmbus_tx_evtflags = NULL;
        }
        if (sc->vmbus_mnf1 != NULL) {
                free(sc->vmbus_mnf1, M_DEVBUF);
                sc->vmbus_mnf1 = NULL;
        }
        if (sc->vmbus_mnf2 != NULL) {
                free(sc->vmbus_mnf2, M_DEVBUF);
                sc->vmbus_mnf2 = NULL;
        }

        CPU_FOREACH(cpu) {
                if (VMBUS_PCPU_GET(sc, message, cpu) != NULL) {
                        free(VMBUS_PCPU_GET(sc, message, cpu), M_DEVBUF);
                        VMBUS_PCPU_GET(sc, message, cpu) = NULL;
                }
                if (VMBUS_PCPU_GET(sc, event_flags, cpu) != NULL) {
                        free(VMBUS_PCPU_GET(sc, event_flags, cpu), M_DEVBUF);
                        VMBUS_PCPU_GET(sc, event_flags, cpu) = NULL;
                }
        }
}

static int
vmbus_intr_setup(struct vmbus_softc *sc)
{
        int cpu;

        CPU_FOREACH(cpu) {
                char buf[MAXCOMLEN + 1];
                cpuset_t cpu_mask;

                /* Allocate an interrupt counter for Hyper-V interrupt */
                snprintf(buf, sizeof(buf), "cpu%d:hyperv", cpu);
#if !defined(__aarch64__)
                intrcnt_add(buf, VMBUS_PCPU_PTR(sc, intr_cnt, cpu));
#endif /* not for aarch64 */
                /*
                 * Setup taskqueue to handle events.  Task will be per-
                 * channel.
                 */
                VMBUS_PCPU_GET(sc, event_tq, cpu) = taskqueue_create_fast(
                    "hyperv event", M_WAITOK, taskqueue_thread_enqueue,
                    VMBUS_PCPU_PTR(sc, event_tq, cpu));
                if (vmbus_pin_evttask) {
                        CPU_SETOF(cpu, &cpu_mask);
                        taskqueue_start_threads_cpuset(
                            VMBUS_PCPU_PTR(sc, event_tq, cpu), 1, PI_NET,
                            &cpu_mask, "hvevent%d", cpu);
                } else {
                        taskqueue_start_threads(
                            VMBUS_PCPU_PTR(sc, event_tq, cpu), 1, PI_NET,
                            "hvevent%d", cpu);
                }

                /*
                 * Setup tasks and taskqueues to handle messages.
                 */
                VMBUS_PCPU_GET(sc, message_tq, cpu) = taskqueue_create_fast(
                    "hyperv msg", M_WAITOK, taskqueue_thread_enqueue,
                    VMBUS_PCPU_PTR(sc, message_tq, cpu));
                CPU_SETOF(cpu, &cpu_mask);
                taskqueue_start_threads_cpuset(
                    VMBUS_PCPU_PTR(sc, message_tq, cpu), 1, PI_NET, &cpu_mask,
                    "hvmsg%d", cpu);
                TASK_INIT(VMBUS_PCPU_PTR(sc, message_task, cpu), 0,
                    vmbus_msg_task, sc);
        }
        return (vmbus_setup_intr1(sc));
}
static void
vmbus_intr_teardown(struct vmbus_softc *sc)
{
        vmbus_intr_teardown1(sc);
}

static int
vmbus_read_ivar(device_t dev, device_t child, int index, uintptr_t *result)
{
        return (ENOENT);
}

static int
vmbus_child_pnpinfo(device_t dev, device_t child, struct sbuf *sb)
{
        const struct vmbus_channel *chan;
        char guidbuf[HYPERV_GUID_STRLEN];

        chan = vmbus_get_channel(child);
        if (chan == NULL) {
                /* Event timer device, which does not belong to a channel */
                return (0);
        }

        hyperv_guid2str(&chan->ch_guid_type, guidbuf, sizeof(guidbuf));
        sbuf_printf(sb, "classid=%s", guidbuf);

        hyperv_guid2str(&chan->ch_guid_inst, guidbuf, sizeof(guidbuf));
        sbuf_printf(sb, " deviceid=%s", guidbuf);

        return (0);
}

int
vmbus_add_child(struct vmbus_channel *chan)
{
        struct vmbus_softc *sc = chan->ch_vmbus;
        device_t parent = sc->vmbus_dev;

        bus_topo_lock();

        chan->ch_dev = device_add_child(parent, NULL, DEVICE_UNIT_ANY);
        if (chan->ch_dev == NULL) {
                bus_topo_unlock();
                device_printf(parent, "device_add_child for chan%u failed\n",
                    chan->ch_id);
                return (ENXIO);
        }
        device_set_ivars(chan->ch_dev, chan);
        device_probe_and_attach(chan->ch_dev);
        bus_topo_unlock();

        return (0);
}

int
vmbus_delete_child(struct vmbus_channel *chan)
{
        int error = 0;

        bus_topo_lock();
        if (chan->ch_dev != NULL) {
                error = device_delete_child(chan->ch_vmbus->vmbus_dev,
                    chan->ch_dev);
                chan->ch_dev = NULL;
        }
        bus_topo_unlock();
        return (error);
}

static int
vmbus_sysctl_version(SYSCTL_HANDLER_ARGS)
{
        struct vmbus_softc *sc = arg1;
        char verstr[16];

        snprintf(verstr, sizeof(verstr), "%u.%u",
            VMBUS_VERSION_MAJOR(sc->vmbus_version),
            VMBUS_VERSION_MINOR(sc->vmbus_version));
        return sysctl_handle_string(oidp, verstr, sizeof(verstr), req);
}

/*
 * We need the function to make sure the MMIO resource is allocated from the
 * ranges found in _CRS.
 *
 * For the release function, we can use bus_generic_release_resource().
 */
static struct resource *
vmbus_alloc_resource(device_t dev, device_t child, int type, int rid,
    rman_res_t start, rman_res_t end, rman_res_t count, u_int flags)
{
        device_t parent = device_get_parent(dev);
        struct resource *res;

        if (type == SYS_RES_MEMORY) {
                struct vmbus_softc *sc = device_get_softc(dev);

                res = pcib_host_res_alloc(&sc->vmbus_mmio_res, child, type,
                    rid, start, end, count, flags);
        } else {
                res = BUS_ALLOC_RESOURCE(parent, child, type, rid, start,
                    end, count, flags);
        }

        return (res);
}

static int
vmbus_alloc_msi(device_t bus, device_t dev, int count, int maxcount, int *irqs)
{

        return (PCIB_ALLOC_MSI(device_get_parent(bus), dev, count, maxcount,
            irqs));
}

static int
vmbus_release_msi(device_t bus, device_t dev, int count, int *irqs)
{

        return (PCIB_RELEASE_MSI(device_get_parent(bus), dev, count, irqs));
}

static int
vmbus_alloc_msix(device_t bus, device_t dev, int *irq)
{

        return (PCIB_ALLOC_MSIX(device_get_parent(bus), dev, irq));
}

static int
vmbus_release_msix(device_t bus, device_t dev, int irq)
{

        return (PCIB_RELEASE_MSIX(device_get_parent(bus), dev, irq));
}

static int
vmbus_map_msi(device_t bus, device_t dev, int irq, uint64_t *addr,
        uint32_t *data)
{

        return (PCIB_MAP_MSI(device_get_parent(bus), dev, irq, addr, data));
}

static uint32_t
vmbus_get_version_method(device_t bus, device_t dev)
{
        struct vmbus_softc *sc = device_get_softc(bus);

        return sc->vmbus_version;
}

static int
vmbus_probe_guid_method(device_t bus, device_t dev,
    const struct hyperv_guid *guid)
{
        const struct vmbus_channel *chan = vmbus_get_channel(dev);

        if (memcmp(&chan->ch_guid_type, guid, sizeof(struct hyperv_guid)) == 0)
                return 0;
        return ENXIO;
}

static uint32_t
vmbus_get_vcpu_id_method(device_t bus, device_t dev, int cpu)
{
        const struct vmbus_softc *sc = device_get_softc(bus);

        return (VMBUS_PCPU_GET(sc, vcpuid, cpu));
}

static struct taskqueue *
vmbus_get_eventtq_method(device_t bus, device_t dev __unused, int cpu)
{
        const struct vmbus_softc *sc = device_get_softc(bus);

        KASSERT(cpu >= 0 && cpu < mp_ncpus, ("invalid cpu%d", cpu));
        return (VMBUS_PCPU_GET(sc, event_tq, cpu));
}

#define VTPM_BASE_ADDR 0xfed40000
#define FOUR_GB (1ULL << 32)

enum parse_pass { parse_64, parse_32 };

struct parse_context {
        device_t vmbus_dev;
        enum parse_pass pass;
};

static ACPI_STATUS
parse_crs(ACPI_RESOURCE *res, void *ctx)
{
        const struct parse_context *pc = ctx;
        device_t vmbus_dev = pc->vmbus_dev;

        struct vmbus_softc *sc = device_get_softc(vmbus_dev);
        UINT64 start, end;

        switch (res->Type) {
        case ACPI_RESOURCE_TYPE_ADDRESS32:
                start = res->Data.Address32.Address.Minimum;
                end = res->Data.Address32.Address.Maximum;
                break;

        case ACPI_RESOURCE_TYPE_ADDRESS64:
                start = res->Data.Address64.Address.Minimum;
                end = res->Data.Address64.Address.Maximum;
                break;

        default:
                /* Unused types. */
                return (AE_OK);
        }

        /*
         * We don't use <1MB addresses.
         */
        if (end < 0x100000)
                return (AE_OK);

        /* Don't conflict with vTPM. */
        if (end >= VTPM_BASE_ADDR && start < VTPM_BASE_ADDR)
                end = VTPM_BASE_ADDR - 1;

        if ((pc->pass == parse_32 && start < FOUR_GB) ||
            (pc->pass == parse_64 && start >= FOUR_GB))
                pcib_host_res_decodes(&sc->vmbus_mmio_res, SYS_RES_MEMORY,
                    start, end, 0);

        return (AE_OK);
}

static void
vmbus_get_crs(device_t dev, device_t vmbus_dev, enum parse_pass pass)
{
        struct parse_context pc;
        ACPI_STATUS status;

        if (bootverbose)
                device_printf(dev, "walking _CRS, pass=%d\n", pass);

        pc.vmbus_dev = vmbus_dev;
        pc.pass = pass;
        status = AcpiWalkResources(acpi_get_handle(dev), "_CRS",
                        parse_crs, &pc);

        if (bootverbose && ACPI_FAILURE(status))
                device_printf(dev, "_CRS: not found, pass=%d\n", pass);
}

static void
vmbus_get_mmio_res_pass(device_t dev, enum parse_pass pass)
{
        device_t acpi0, parent;

        parent = device_get_parent(dev);

        acpi0 = device_get_parent(parent);
        if (strcmp("acpi0", device_get_nameunit(acpi0)) == 0) {
                device_t *children;
                int count;

                /*
                 * Try to locate VMBUS resources and find _CRS on them.
                 */
                if (device_get_children(acpi0, &children, &count) == 0) {
                        int i;

                        for (i = 0; i < count; ++i) {
                                if (!device_is_attached(children[i]))
                                        continue;

                                if (strcmp("vmbus_res",
                                    device_get_name(children[i])) == 0)
                                        vmbus_get_crs(children[i], dev, pass);
                        }
                        free(children, M_TEMP);
                }

                /*
                 * Try to find _CRS on acpi.
                 */
                vmbus_get_crs(acpi0, dev, pass);
        } else {
                device_printf(dev, "not grandchild of acpi\n");
        }

        /*
         * Try to find _CRS on parent.
         */
        vmbus_get_crs(parent, dev, pass);
}

static void
vmbus_get_mmio_res(device_t dev)
{
        struct vmbus_softc *sc = device_get_softc(dev);
        /*
         * We walk the resources twice to make sure that: in the resource
         * list, the 32-bit resources appear behind the 64-bit resources.
         * NB: resource_list_add() uses INSERT_TAIL. This way, when we
         * iterate through the list to find a range for a 64-bit BAR in
         * vmbus_alloc_resource(), we can make sure we try to use >4GB
         * ranges first.
         */
        pcib_host_res_init(dev, &sc->vmbus_mmio_res);

        vmbus_get_mmio_res_pass(dev, parse_64);
        vmbus_get_mmio_res_pass(dev, parse_32);
}

/*
 * On Gen2 VMs, Hyper-V provides mmio space for framebuffer.
 * This mmio address range is not useable for other PCI devices.
 * Currently only efifb and vbefb drivers are using this range without
 * reserving it from system.
 * Therefore, vmbus driver reserves it before any other PCI device
 * drivers start to request mmio addresses.
 */
static struct resource *hv_fb_res;

static void
vmbus_fb_mmio_res(device_t dev)
{
        struct efi_fb *efifb;
#if !defined(__aarch64__)
        struct vbe_fb *vbefb;
#endif /* aarch64 */
        rman_res_t fb_start, fb_end, fb_count;
        int fb_height, fb_width;

        struct vmbus_softc *sc = device_get_softc(dev);
        int rid = 0;

        efifb = (struct efi_fb *)preload_search_info(preload_kmdp,
            MODINFO_METADATA | MODINFOMD_EFI_FB);
#if !defined(__aarch64__)
        vbefb = (struct vbe_fb *)preload_search_info(preload_kmdp,
            MODINFO_METADATA | MODINFOMD_VBE_FB);
#endif /* aarch64 */
        if (efifb != NULL) {
                fb_start = efifb->fb_addr;
                fb_end = efifb->fb_addr + efifb->fb_size;
                fb_count = efifb->fb_size;
                fb_height = efifb->fb_height;
                fb_width = efifb->fb_width;
        }
#if !defined(__aarch64__)
        else if (vbefb != NULL) {
                fb_start = vbefb->fb_addr;
                fb_end = vbefb->fb_addr + vbefb->fb_size;
                fb_count = vbefb->fb_size;
                fb_height = vbefb->fb_height;
                fb_width = vbefb->fb_width;
        }
#endif /* aarch64 */
        else {
                if (bootverbose)
                        device_printf(dev,
                            "no preloaded kernel fb information\n");
                /* We are on Gen1 VM, just return. */
                return;
        }

        if (bootverbose)
                device_printf(dev,
                    "fb: fb_addr: %#jx, size: %#jx, "
                    "actual size needed: 0x%x\n",
                    fb_start, fb_count, fb_height * fb_width);

        hv_fb_res = pcib_host_res_alloc(&sc->vmbus_mmio_res, dev,
            SYS_RES_MEMORY, rid, fb_start, fb_end, fb_count,
            RF_ACTIVE | rman_make_alignment_flags(PAGE_SIZE));

        if (hv_fb_res && bootverbose)
                device_printf(dev,
                    "successfully reserved memory for framebuffer "
                    "starting at %#jx, size %#jx\n",
                    fb_start, fb_count);
}

static void
vmbus_free_mmio_res(device_t dev)
{
        struct vmbus_softc *sc = device_get_softc(dev);

        pcib_host_res_free(dev, &sc->vmbus_mmio_res);

        if (hv_fb_res)
                hv_fb_res = NULL;
}

static void
vmbus_identify(driver_t *driver, device_t parent)
{

        if (device_get_unit(parent) != 0 || vm_guest != VM_GUEST_HV ||
            (hyperv_features & CPUID_HV_MSR_SYNIC) == 0)
                return;
        device_add_child(parent, "vmbus", DEVICE_UNIT_ANY);
}

static int
vmbus_probe(device_t dev)
{

        if (device_get_unit(dev) != 0 || vm_guest != VM_GUEST_HV ||
            (hyperv_features & CPUID_HV_MSR_SYNIC) == 0)
                return (ENXIO);

        device_set_desc(dev, "Hyper-V Vmbus");
        return (BUS_PROBE_DEFAULT);
}

#if defined(__x86_64__)
static int
vmbus_alloc_cpu_mem(struct vmbus_softc *sc)
{
        int cpu;

        CPU_FOREACH(cpu) {
                void **hv_cpu_mem;

                hv_cpu_mem = VMBUS_PCPU_PTR(sc, cpu_mem, cpu);
                *hv_cpu_mem = contigmalloc(PAGE_SIZE, M_DEVBUF,
                    M_NOWAIT | M_ZERO, 0ul, ~0ul, PAGE_SIZE, 0);

                if (*hv_cpu_mem == NULL)
                        return ENOMEM;
        }

        return 0;
}

static void
vmbus_free_cpu_mem(struct vmbus_softc *sc)
{
        int cpu;

        CPU_FOREACH(cpu) {
                void **hv_cpu_mem;
                hv_cpu_mem = VMBUS_PCPU_PTR(sc, cpu_mem, cpu);
                if(*hv_cpu_mem != NULL) {
                        free(*hv_cpu_mem, M_DEVBUF);
                        *hv_cpu_mem = NULL;
                }
        }
}
#endif

/**
 * @brief Main vmbus driver initialization routine.
 *
 * Here, we
 * - initialize the vmbus driver context
 * - setup various driver entry points
 * - invoke the vmbus hv main init routine
 * - get the irq resource
 * - invoke the vmbus to add the vmbus root device
 * - setup the vmbus root device
 * - retrieve the channel offers
 */
static int
vmbus_doattach(struct vmbus_softc *sc)
{
        struct sysctl_oid_list *child;
        struct sysctl_ctx_list *ctx;
        int ret;
        device_t dev_res;
        ACPI_HANDLE handle;
        unsigned int coherent = 0;

        if (sc->vmbus_flags & VMBUS_FLAG_ATTACHED)
                return (0);

        vmbus_get_mmio_res(sc->vmbus_dev);
        vmbus_fb_mmio_res(sc->vmbus_dev);

        sc->vmbus_flags |= VMBUS_FLAG_ATTACHED;

        sc->vmbus_gpadl = VMBUS_GPADL_START;
        mtx_init(&sc->vmbus_prichan_lock, "vmbus prichan", NULL, MTX_DEF);
        TAILQ_INIT(&sc->vmbus_prichans);
        mtx_init(&sc->vmbus_chan_lock, "vmbus channel", NULL, MTX_DEF);
        TAILQ_INIT(&sc->vmbus_chans);
        sc->vmbus_chmap = malloc(
            sizeof(struct vmbus_channel *) * VMBUS_CHAN_MAX, M_DEVBUF,
            M_WAITOK | M_ZERO);

        /* Coherency attribute */
        dev_res =  devclass_get_device(devclass_find("vmbus_res"), 0);
        if (dev_res != NULL) {
                handle = acpi_get_handle(dev_res);

                if (ACPI_FAILURE(acpi_GetInteger(handle, "_CCA", &coherent)))
                        coherent = 0;
        }
        if (bootverbose)
                device_printf(sc->vmbus_dev, "Bus is%s cache-coherent\n",
                        coherent ? "" : " not");

        bus_dma_tag_create(bus_get_dma_tag(sc->vmbus_dev),
                1, 0,
                BUS_SPACE_MAXADDR,
                BUS_SPACE_MAXADDR,
                NULL, NULL,
                BUS_SPACE_MAXSIZE,
                BUS_SPACE_UNRESTRICTED,
                BUS_SPACE_MAXSIZE,
                coherent ? BUS_DMA_COHERENT : 0,
                NULL, NULL,
                &sc->dmat);
        /*
         * Create context for "post message" Hypercalls
         */
        sc->vmbus_xc = vmbus_xact_ctx_create(bus_get_dma_tag(sc->vmbus_dev),
            HYPERCALL_POSTMSGIN_SIZE, VMBUS_MSG_SIZE,
            sizeof(struct vmbus_msghc));
        if (sc->vmbus_xc == NULL) {
                ret = ENXIO;
                goto cleanup;
        }

        /*
         * Allocate DMA stuffs.
         */
        ret = vmbus_dma_alloc(sc);
        if (ret != 0)
                goto cleanup;

        /*
         * Setup interrupt.
         */
        ret = vmbus_intr_setup(sc);
        if (ret != 0)
                goto cleanup;

#if defined(__x86_64__)
        /*
         * Alloc per cpu memory for tlb flush hypercall
         */
        if (hv_tlb_hcall) {
                ret = vmbus_alloc_cpu_mem(sc);
                if (ret != 0) {
                        hv_tlb_hcall = 0;
                        if (bootverbose)
                                device_printf(sc->vmbus_dev,
                                    "cannot alloc contig memory for "
                                    "cpu_mem, use system provided "
                                    "tlb flush call.\n");

                        vmbus_free_cpu_mem(sc);
                }
        }
#endif

        /*
         * Setup SynIC.
         */
        if (bootverbose)
                device_printf(sc->vmbus_dev, "smp_started = %d\n", smp_started);
        smp_rendezvous(NULL, vmbus_synic_setup, NULL, sc);
        sc->vmbus_flags |= VMBUS_FLAG_SYNIC;

#if defined(__x86_64__)
        if (hv_tlb_hcall)
                smp_targeted_tlb_shootdown = &hyperv_vm_tlb_flush;
#endif

        /*
         * Initialize vmbus, e.g. connect to Hypervisor.
         */
        ret = vmbus_init(sc);
        if (ret != 0)
                goto cleanup;

        if (sc->vmbus_version == VMBUS_VERSION_WS2008 ||
            sc->vmbus_version == VMBUS_VERSION_WIN7)
                sc->vmbus_event_proc = vmbus_event_proc_compat;
        else
                sc->vmbus_event_proc = vmbus_event_proc;

        ret = vmbus_scan(sc);
        if (ret != 0)
                goto cleanup;

        ctx = device_get_sysctl_ctx(sc->vmbus_dev);
        child = SYSCTL_CHILDREN(device_get_sysctl_tree(sc->vmbus_dev));
        SYSCTL_ADD_PROC(ctx, child, OID_AUTO, "version",
            CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, sc, 0,
            vmbus_sysctl_version, "A", "vmbus version");

        return (ret);

cleanup:
        vmbus_scan_teardown(sc);
        vmbus_intr_teardown(sc);
        vmbus_dma_free(sc);
        if (sc->vmbus_xc != NULL) {
                vmbus_xact_ctx_destroy(sc->vmbus_xc);
                sc->vmbus_xc = NULL;
        }
        free(__DEVOLATILE(void *, sc->vmbus_chmap), M_DEVBUF);
        mtx_destroy(&sc->vmbus_prichan_lock);
        mtx_destroy(&sc->vmbus_chan_lock);

        return (ret);
}

static void
vmbus_event_proc_dummy(struct vmbus_softc *sc __unused, int cpu __unused)
{
}

#if defined(EARLY_AP_STARTUP)

static void
vmbus_intrhook(void *xsc)
{
        struct vmbus_softc *sc = xsc;

        if (bootverbose)
                device_printf(sc->vmbus_dev, "intrhook\n");
        vmbus_doattach(sc);
        config_intrhook_disestablish(&sc->vmbus_intrhook);
}

#endif /* EARLY_AP_STARTUP */

static int
vmbus_attach(device_t dev)
{
        vmbus_sc = device_get_softc(dev);
        vmbus_sc->vmbus_dev = dev;
        vmbus_sc->vmbus_idtvec = -1;

        /*
         * Event processing logic will be configured:
         * - After the vmbus protocol version negotiation.
         * - Before we request channel offers.
         */
        vmbus_sc->vmbus_event_proc = vmbus_event_proc_dummy;

#if defined(EARLY_AP_STARTUP)
        /*
         * Defer the real attach until the pause(9) works as expected.
         */
        vmbus_sc->vmbus_intrhook.ich_func = vmbus_intrhook;
        vmbus_sc->vmbus_intrhook.ich_arg = vmbus_sc;
        config_intrhook_establish(&vmbus_sc->vmbus_intrhook);
#endif /* EARLY_AP_STARTUP  and aarch64 */

        return (0);
}

static int
vmbus_detach(device_t dev)
{
        struct vmbus_softc *sc = device_get_softc(dev);

        bus_generic_detach(dev);
        vmbus_chan_destroy_all(sc);

        vmbus_scan_teardown(sc);

        vmbus_disconnect(sc);

        if (sc->vmbus_flags & VMBUS_FLAG_SYNIC) {
                sc->vmbus_flags &= ~VMBUS_FLAG_SYNIC;
                smp_rendezvous(NULL, vmbus_synic_teardown, NULL, NULL);
        }

#if defined(__x86_64__)
        /*
         * Restore the tlb flush to native call
         */
        if (hv_tlb_hcall) {
                smp_targeted_tlb_shootdown = &smp_targeted_tlb_shootdown_native;
                vmbus_free_cpu_mem(sc);
        }
#endif

        vmbus_intr_teardown(sc);
        vmbus_dma_free(sc);

        if (sc->vmbus_xc != NULL) {
                vmbus_xact_ctx_destroy(sc->vmbus_xc);
                sc->vmbus_xc = NULL;
        }

        free(__DEVOLATILE(void *, sc->vmbus_chmap), M_DEVBUF);
        mtx_destroy(&sc->vmbus_prichan_lock);
        mtx_destroy(&sc->vmbus_chan_lock);

        vmbus_free_mmio_res(dev);

#if defined(__aarch64__)
        bus_release_resource(device_get_parent(dev), SYS_RES_IRQ, sc->vector,
            sc->ires);
#endif
        return (0);
}

#if !defined(EARLY_AP_STARTUP)

static void
vmbus_sysinit(void *arg __unused)
{
        struct vmbus_softc *sc = vmbus_get_softc();

        if (vm_guest != VM_GUEST_HV || sc == NULL)
                return;

        vmbus_doattach(sc);
}
/*
 * NOTE:
 * We have to start as the last step of SI_SUB_SMP, i.e. after SMP is
 * initialized.
 */
SYSINIT(vmbus_initialize, SI_SUB_SMP, SI_ORDER_ANY, vmbus_sysinit, NULL);
#endif  /* !EARLY_AP_STARTUP */