/*
 * VMware VMCI Driver
 *
 * Copyright (C) 2012 VMware, Inc. All rights reserved.
 *
 * 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 version 2 and no 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.  See the GNU General Public License
 * for more details.
 */

#include <linux/vmw_vmci_defs.h>
#include <linux/vmw_vmci_api.h>
#include <linux/moduleparam.h>
#include <linux/interrupt.h>
#include <linux/highmem.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/pci.h>
#include <linux/smp.h>
#include <linux/io.h>
#include <linux/vmalloc.h>

#include "vmci_datagram.h"
#include "vmci_doorbell.h"
#include "vmci_context.h"
#include "vmci_driver.h"
#include "vmci_event.h"

#define PCI_DEVICE_ID_VMWARE_VMCI       0x0740

#define VMCI_UTIL_NUM_RESOURCES 1

static bool vmci_disable_msi;
module_param_named(disable_msi, vmci_disable_msi, bool, 0);
MODULE_PARM_DESC(disable_msi, "Disable MSI use in driver - (default=0)");

static bool vmci_disable_msix;
module_param_named(disable_msix, vmci_disable_msix, bool, 0);
MODULE_PARM_DESC(disable_msix, "Disable MSI-X use in driver - (default=0)");

static u32 ctx_update_sub_id = VMCI_INVALID_ID;
static u32 vm_context_id = VMCI_INVALID_ID;

struct vmci_guest_device {
        struct device *dev;     /* PCI device we are attached to */
        void __iomem *iobase;

        unsigned int irq;
        unsigned int intr_type;
        bool exclusive_vectors;
        struct msix_entry msix_entries[VMCI_MAX_INTRS];

        struct tasklet_struct datagram_tasklet;
        struct tasklet_struct bm_tasklet;

        void *data_buffer;
        void *notification_bitmap;
        dma_addr_t notification_base;
};

/* vmci_dev singleton device and supporting data*/
struct pci_dev *vmci_pdev;
static struct vmci_guest_device *vmci_dev_g;
static DEFINE_SPINLOCK(vmci_dev_spinlock);

static atomic_t vmci_num_guest_devices = ATOMIC_INIT(0);

bool vmci_guest_code_active(void)
{
        return atomic_read(&vmci_num_guest_devices) != 0;
}

u32 vmci_get_vm_context_id(void)
{
        if (vm_context_id == VMCI_INVALID_ID) {
                struct vmci_datagram get_cid_msg;
                get_cid_msg.dst =
                    vmci_make_handle(VMCI_HYPERVISOR_CONTEXT_ID,
                                     VMCI_GET_CONTEXT_ID);
                get_cid_msg.src = VMCI_ANON_SRC_HANDLE;
                get_cid_msg.payload_size = 0;
                vm_context_id = vmci_send_datagram(&get_cid_msg);
        }
        return vm_context_id;
}

/*
 * VM to hypervisor call mechanism. We use the standard VMware naming
 * convention since shared code is calling this function as well.
 */
int vmci_send_datagram(struct vmci_datagram *dg)
{
        unsigned long flags;
        int result;

        /* Check args. */
        if (dg == NULL)
                return VMCI_ERROR_INVALID_ARGS;

        /*
         * Need to acquire spinlock on the device because the datagram
         * data may be spread over multiple pages and the monitor may
         * interleave device user rpc calls from multiple
         * VCPUs. Acquiring the spinlock precludes that
         * possibility. Disabling interrupts to avoid incoming
         * datagrams during a "rep out" and possibly landing up in
         * this function.
         */
        spin_lock_irqsave(&vmci_dev_spinlock, flags);

        if (vmci_dev_g) {
                iowrite8_rep(vmci_dev_g->iobase + VMCI_DATA_OUT_ADDR,
                             dg, VMCI_DG_SIZE(dg));
                result = ioread32(vmci_dev_g->iobase + VMCI_RESULT_LOW_ADDR);
        } else {
                result = VMCI_ERROR_UNAVAILABLE;
        }

        spin_unlock_irqrestore(&vmci_dev_spinlock, flags);

        return result;
}
EXPORT_SYMBOL_GPL(vmci_send_datagram);

/*
 * Gets called with the new context id if updated or resumed.
 * Context id.
 */
static void vmci_guest_cid_update(u32 sub_id,
                                  const struct vmci_event_data *event_data,
                                  void *client_data)
{
        const struct vmci_event_payld_ctx *ev_payload =
                                vmci_event_data_const_payload(event_data);

        if (sub_id != ctx_update_sub_id) {
                pr_devel("Invalid subscriber (ID=0x%x)\n", sub_id);
                return;
        }

        if (!event_data || ev_payload->context_id == VMCI_INVALID_ID) {
                pr_devel("Invalid event data\n");
                return;
        }

        pr_devel("Updating context from (ID=0x%x) to (ID=0x%x) on event (type=%d)\n",
                 vm_context_id, ev_payload->context_id, event_data->event);

        vm_context_id = ev_payload->context_id;
}

/*
 * Verify that the host supports the hypercalls we need. If it does not,
 * try to find fallback hypercalls and use those instead.  Returns
 * true if required hypercalls (or fallback hypercalls) are
 * supported by the host, false otherwise.
 */
static int vmci_check_host_caps(struct pci_dev *pdev)
{
        bool result;
        struct vmci_resource_query_msg *msg;
        u32 msg_size = sizeof(struct vmci_resource_query_hdr) +
                                VMCI_UTIL_NUM_RESOURCES * sizeof(u32);
        struct vmci_datagram *check_msg;

        check_msg = kmalloc(msg_size, GFP_KERNEL);
        if (!check_msg) {
                dev_err(&pdev->dev, "%s: Insufficient memory\n", __func__);
                return -ENOMEM;
        }

        check_msg->dst = vmci_make_handle(VMCI_HYPERVISOR_CONTEXT_ID,
                                          VMCI_RESOURCES_QUERY);
        check_msg->src = VMCI_ANON_SRC_HANDLE;
        check_msg->payload_size = msg_size - VMCI_DG_HEADERSIZE;
        msg = (struct vmci_resource_query_msg *)VMCI_DG_PAYLOAD(check_msg);

        msg->num_resources = VMCI_UTIL_NUM_RESOURCES;
        msg->resources[0] = VMCI_GET_CONTEXT_ID;

        /* Checks that hyper calls are supported */
        result = vmci_send_datagram(check_msg) == 0x01;
        kfree(check_msg);

        dev_dbg(&pdev->dev, "%s: Host capability check: %s\n",
                __func__, result ? "PASSED" : "FAILED");

        /* We need the vector. There are no fallbacks. */
        return result ? 0 : -ENXIO;
}

/*
 * Reads datagrams from the data in port and dispatches them. We
 * always start reading datagrams into only the first page of the
 * datagram buffer. If the datagrams don't fit into one page, we
 * use the maximum datagram buffer size for the remainder of the
 * invocation. This is a simple heuristic for not penalizing
 * small datagrams.
 *
 * This function assumes that it has exclusive access to the data
 * in port for the duration of the call.
 */
static void vmci_dispatch_dgs(unsigned long data)
{
        struct vmci_guest_device *vmci_dev = (struct vmci_guest_device *)data;
        u8 *dg_in_buffer = vmci_dev->data_buffer;
        struct vmci_datagram *dg;
        size_t dg_in_buffer_size = VMCI_MAX_DG_SIZE;
        size_t current_dg_in_buffer_size = PAGE_SIZE;
        size_t remaining_bytes;

        BUILD_BUG_ON(VMCI_MAX_DG_SIZE < PAGE_SIZE);

        ioread8_rep(vmci_dev->iobase + VMCI_DATA_IN_ADDR,
                    vmci_dev->data_buffer, current_dg_in_buffer_size);
        dg = (struct vmci_datagram *)dg_in_buffer;
        remaining_bytes = current_dg_in_buffer_size;

        while (dg->dst.resource != VMCI_INVALID_ID ||
               remaining_bytes > PAGE_SIZE) {
                unsigned dg_in_size;

                /*
                 * When the input buffer spans multiple pages, a datagram can
                 * start on any page boundary in the buffer.
                 */
                if (dg->dst.resource == VMCI_INVALID_ID) {
                        dg = (struct vmci_datagram *)roundup(
                                (uintptr_t)dg + 1, PAGE_SIZE);
                        remaining_bytes =
                                (size_t)(dg_in_buffer +
                                         current_dg_in_buffer_size -
                                         (u8 *)dg);
                        continue;
                }

                dg_in_size = VMCI_DG_SIZE_ALIGNED(dg);

                if (dg_in_size <= dg_in_buffer_size) {
                        int result;

                        /*
                         * If the remaining bytes in the datagram
                         * buffer doesn't contain the complete
                         * datagram, we first make sure we have enough
                         * room for it and then we read the reminder
                         * of the datagram and possibly any following
                         * datagrams.
                         */
                        if (dg_in_size > remaining_bytes) {
                                if (remaining_bytes !=
                                    current_dg_in_buffer_size) {

                                        /*
                                         * We move the partial
                                         * datagram to the front and
                                         * read the reminder of the
                                         * datagram and possibly
                                         * following calls into the
                                         * following bytes.
                                         */
                                        memmove(dg_in_buffer, dg_in_buffer +
                                                current_dg_in_buffer_size -
                                                remaining_bytes,
                                                remaining_bytes);
                                        dg = (struct vmci_datagram *)
                                            dg_in_buffer;
                                }

                                if (current_dg_in_buffer_size !=
                                    dg_in_buffer_size)
                                        current_dg_in_buffer_size =
                                            dg_in_buffer_size;

                                ioread8_rep(vmci_dev->iobase +
                                                VMCI_DATA_IN_ADDR,
                                        vmci_dev->data_buffer +
                                                remaining_bytes,
                                        current_dg_in_buffer_size -
                                                remaining_bytes);
                        }

                        /*
                         * We special case event datagrams from the
                         * hypervisor.
                         */
                        if (dg->src.context == VMCI_HYPERVISOR_CONTEXT_ID &&
                            dg->dst.resource == VMCI_EVENT_HANDLER) {
                                result = vmci_event_dispatch(dg);
                        } else {
                                result = vmci_datagram_invoke_guest_handler(dg);
                        }
                        if (result < VMCI_SUCCESS)
                                dev_dbg(vmci_dev->dev,
                                        "Datagram with resource (ID=0x%x) failed (err=%d)\n",
                                         dg->dst.resource, result);

                        /* On to the next datagram. */
                        dg = (struct vmci_datagram *)((u8 *)dg +
                                                      dg_in_size);
                } else {
                        size_t bytes_to_skip;

                        /*
                         * Datagram doesn't fit in datagram buffer of maximal
                         * size. We drop it.
                         */
                        dev_dbg(vmci_dev->dev,
                                "Failed to receive datagram (size=%u bytes)\n",
                                 dg_in_size);

                        bytes_to_skip = dg_in_size - remaining_bytes;
                        if (current_dg_in_buffer_size != dg_in_buffer_size)
                                current_dg_in_buffer_size = dg_in_buffer_size;

                        for (;;) {
                                ioread8_rep(vmci_dev->iobase +
                                                VMCI_DATA_IN_ADDR,
                                        vmci_dev->data_buffer,
                                        current_dg_in_buffer_size);
                                if (bytes_to_skip <= current_dg_in_buffer_size)
                                        break;

                                bytes_to_skip -= current_dg_in_buffer_size;
                        }
                        dg = (struct vmci_datagram *)(dg_in_buffer +
                                                      bytes_to_skip);
                }

                remaining_bytes =
                    (size_t) (dg_in_buffer + current_dg_in_buffer_size -
                              (u8 *)dg);

                if (remaining_bytes < VMCI_DG_HEADERSIZE) {
                        /* Get the next batch of datagrams. */

                        ioread8_rep(vmci_dev->iobase + VMCI_DATA_IN_ADDR,
                                    vmci_dev->data_buffer,
                                    current_dg_in_buffer_size);
                        dg = (struct vmci_datagram *)dg_in_buffer;
                        remaining_bytes = current_dg_in_buffer_size;
                }
        }
}

/*
 * Scans the notification bitmap for raised flags, clears them
 * and handles the notifications.
 */
static void vmci_process_bitmap(unsigned long data)
{
        struct vmci_guest_device *dev = (struct vmci_guest_device *)data;

        if (!dev->notification_bitmap) {
                dev_dbg(dev->dev, "No bitmap present in %s\n", __func__);
                return;
        }

        vmci_dbell_scan_notification_entries(dev->notification_bitmap);
}

/*
 * Enable MSI-X.  Try exclusive vectors first, then shared vectors.
 */
static int vmci_enable_msix(struct pci_dev *pdev,
                            struct vmci_guest_device *vmci_dev)
{
        int i;
        int result;

        for (i = 0; i < VMCI_MAX_INTRS; ++i) {
                vmci_dev->msix_entries[i].entry = i;
                vmci_dev->msix_entries[i].vector = i;
        }

        result = pci_enable_msix(pdev, vmci_dev->msix_entries, VMCI_MAX_INTRS);
        if (result == 0)
                vmci_dev->exclusive_vectors = true;
        else if (result > 0)
                result = pci_enable_msix(pdev, vmci_dev->msix_entries, 1);

        return result;
}

/*
 * Interrupt handler for legacy or MSI interrupt, or for first MSI-X
 * interrupt (vector VMCI_INTR_DATAGRAM).
 */
static irqreturn_t vmci_interrupt(int irq, void *_dev)
{
        struct vmci_guest_device *dev = _dev;

        /*
         * If we are using MSI-X with exclusive vectors then we simply schedule
         * the datagram tasklet, since we know the interrupt was meant for us.
         * Otherwise we must read the ICR to determine what to do.
         */

        if (dev->intr_type == VMCI_INTR_TYPE_MSIX && dev->exclusive_vectors) {
                tasklet_schedule(&dev->datagram_tasklet);
        } else {
                unsigned int icr;

                /* Acknowledge interrupt and determine what needs doing. */
                icr = ioread32(dev->iobase + VMCI_ICR_ADDR);
                if (icr == 0 || icr == ~0)
                        return IRQ_NONE;

                if (icr & VMCI_ICR_DATAGRAM) {
                        tasklet_schedule(&dev->datagram_tasklet);
                        icr &= ~VMCI_ICR_DATAGRAM;
                }

                if (icr & VMCI_ICR_NOTIFICATION) {
                        tasklet_schedule(&dev->bm_tasklet);
                        icr &= ~VMCI_ICR_NOTIFICATION;
                }

                if (icr != 0)
                        dev_warn(dev->dev,
                                 "Ignoring unknown interrupt cause (%d)\n",
                                 icr);
        }

        return IRQ_HANDLED;
}

/*
 * Interrupt handler for MSI-X interrupt vector VMCI_INTR_NOTIFICATION,
 * which is for the notification bitmap.  Will only get called if we are
 * using MSI-X with exclusive vectors.
 */
static irqreturn_t vmci_interrupt_bm(int irq, void *_dev)
{
        struct vmci_guest_device *dev = _dev;

        /* For MSI-X we can just assume it was meant for us. */
        tasklet_schedule(&dev->bm_tasklet);

        return IRQ_HANDLED;
}

/*
 * Most of the initialization at module load time is done here.
 */
static int vmci_guest_probe_device(struct pci_dev *pdev,
                                   const struct pci_device_id *id)
{
        struct vmci_guest_device *vmci_dev;
        void __iomem *iobase;
        unsigned int capabilities;
        unsigned long cmd;
        int vmci_err;
        int error;

        dev_dbg(&pdev->dev, "Probing for vmci/PCI guest device\n");

        error = pcim_enable_device(pdev);
        if (error) {
                dev_err(&pdev->dev,
                        "Failed to enable VMCI device: %d\n", error);
                return error;
        }

        error = pcim_iomap_regions(pdev, 1 << 0, KBUILD_MODNAME);
        if (error) {
                dev_err(&pdev->dev, "Failed to reserve/map IO regions\n");
                return error;
        }

        iobase = pcim_iomap_table(pdev)[0];

        dev_info(&pdev->dev, "Found VMCI PCI device at %#lx, irq %u\n",
                 (unsigned long)iobase, pdev->irq);

        vmci_dev = devm_kzalloc(&pdev->dev, sizeof(*vmci_dev), GFP_KERNEL);
        if (!vmci_dev) {
                dev_err(&pdev->dev,
                        "Can't allocate memory for VMCI device\n");
                return -ENOMEM;
        }

        vmci_dev->dev = &pdev->dev;
        vmci_dev->intr_type = VMCI_INTR_TYPE_INTX;
        vmci_dev->exclusive_vectors = false;
        vmci_dev->iobase = iobase;

        tasklet_init(&vmci_dev->datagram_tasklet,
                     vmci_dispatch_dgs, (unsigned long)vmci_dev);
        tasklet_init(&vmci_dev->bm_tasklet,
                     vmci_process_bitmap, (unsigned long)vmci_dev);

        vmci_dev->data_buffer = vmalloc(VMCI_MAX_DG_SIZE);
        if (!vmci_dev->data_buffer) {
                dev_err(&pdev->dev,
                        "Can't allocate memory for datagram buffer\n");
                return -ENOMEM;
        }

        pci_set_master(pdev);   /* To enable queue_pair functionality. */

        /*
         * Verify that the VMCI Device supports the capabilities that
         * we need. If the device is missing capabilities that we would
         * like to use, check for fallback capabilities and use those
         * instead (so we can run a new VM on old hosts). Fail the load if
         * a required capability is missing and there is no fallback.
         *
         * Right now, we need datagrams. There are no fallbacks.
         */
        capabilities = ioread32(vmci_dev->iobase + VMCI_CAPS_ADDR);
        if (!(capabilities & VMCI_CAPS_DATAGRAM)) {
                dev_err(&pdev->dev, "Device does not support datagrams\n");
                error = -ENXIO;
                goto err_free_data_buffer;
        }

        /*
         * If the hardware supports notifications, we will use that as
         * well.
         */
        if (capabilities & VMCI_CAPS_NOTIFICATIONS) {
                vmci_dev->notification_bitmap = dma_alloc_coherent(
                        &pdev->dev, PAGE_SIZE, &vmci_dev->notification_base,
                        GFP_KERNEL);
                if (!vmci_dev->notification_bitmap) {
                        dev_warn(&pdev->dev,
                                 "Unable to allocate notification bitmap\n");
                } else {
                        memset(vmci_dev->notification_bitmap, 0, PAGE_SIZE);
                        capabilities |= VMCI_CAPS_NOTIFICATIONS;
                }
        }

        dev_info(&pdev->dev, "Using capabilities 0x%x\n", capabilities);

        /* Let the host know which capabilities we intend to use. */
        iowrite32(capabilities, vmci_dev->iobase + VMCI_CAPS_ADDR);

        /* Set up global device so that we can start sending datagrams */
        spin_lock_irq(&vmci_dev_spinlock);
        vmci_dev_g = vmci_dev;
        vmci_pdev = pdev;
        spin_unlock_irq(&vmci_dev_spinlock);

        /*
         * Register notification bitmap with device if that capability is
         * used.
         */
        if (capabilities & VMCI_CAPS_NOTIFICATIONS) {
                unsigned long bitmap_ppn =
                        vmci_dev->notification_base >> PAGE_SHIFT;
                if (!vmci_dbell_register_notification_bitmap(bitmap_ppn)) {
                        dev_warn(&pdev->dev,
                                 "VMCI device unable to register notification bitmap with PPN 0x%x\n",
                                 (u32) bitmap_ppn);
                        error = -ENXIO;
                        goto err_remove_vmci_dev_g;
                }
        }

        /* Check host capabilities. */
        error = vmci_check_host_caps(pdev);
        if (error)
                goto err_remove_bitmap;

        /* Enable device. */

        /*
         * We subscribe to the VMCI_EVENT_CTX_ID_UPDATE here so we can
         * update the internal context id when needed.
         */
        vmci_err = vmci_event_subscribe(VMCI_EVENT_CTX_ID_UPDATE,
                                        vmci_guest_cid_update, NULL,
                                        &ctx_update_sub_id);
        if (vmci_err < VMCI_SUCCESS)
                dev_warn(&pdev->dev,
                         "Failed to subscribe to event (type=%d): %d\n",
                         VMCI_EVENT_CTX_ID_UPDATE, vmci_err);

        /*
         * Enable interrupts.  Try MSI-X first, then MSI, and then fallback on
         * legacy interrupts.
         */
        if (!vmci_disable_msix && !vmci_enable_msix(pdev, vmci_dev)) {
                vmci_dev->intr_type = VMCI_INTR_TYPE_MSIX;
                vmci_dev->irq = vmci_dev->msix_entries[0].vector;
        } else if (!vmci_disable_msi && !pci_enable_msi(pdev)) {
                vmci_dev->intr_type = VMCI_INTR_TYPE_MSI;
                vmci_dev->irq = pdev->irq;
        } else {
                vmci_dev->intr_type = VMCI_INTR_TYPE_INTX;
                vmci_dev->irq = pdev->irq;
        }

        /*
         * Request IRQ for legacy or MSI interrupts, or for first
         * MSI-X vector.
         */
        error = request_irq(vmci_dev->irq, vmci_interrupt, IRQF_SHARED,
                            KBUILD_MODNAME, vmci_dev);
        if (error) {
                dev_err(&pdev->dev, "Irq %u in use: %d\n",
                        vmci_dev->irq, error);
                goto err_disable_msi;
        }

        /*
         * For MSI-X with exclusive vectors we need to request an
         * interrupt for each vector so that we get a separate
         * interrupt handler routine.  This allows us to distinguish
         * between the vectors.
         */
        if (vmci_dev->exclusive_vectors) {
                error = request_irq(vmci_dev->msix_entries[1].vector,
                                    vmci_interrupt_bm, 0, KBUILD_MODNAME,
                                    vmci_dev);
                if (error) {
                        dev_err(&pdev->dev,
                                "Failed to allocate irq %u: %d\n",
                                vmci_dev->msix_entries[1].vector, error);
                        goto err_free_irq;
                }
        }

        dev_dbg(&pdev->dev, "Registered device\n");

        atomic_inc(&vmci_num_guest_devices);

        /* Enable specific interrupt bits. */
        cmd = VMCI_IMR_DATAGRAM;
        if (capabilities & VMCI_CAPS_NOTIFICATIONS)
                cmd |= VMCI_IMR_NOTIFICATION;
        iowrite32(cmd, vmci_dev->iobase + VMCI_IMR_ADDR);

        /* Enable interrupts. */
        iowrite32(VMCI_CONTROL_INT_ENABLE,
                  vmci_dev->iobase + VMCI_CONTROL_ADDR);

        pci_set_drvdata(pdev, vmci_dev);
        return 0;

err_free_irq:
        free_irq(vmci_dev->irq, &vmci_dev);
        tasklet_kill(&vmci_dev->datagram_tasklet);
        tasklet_kill(&vmci_dev->bm_tasklet);

err_disable_msi:
        if (vmci_dev->intr_type == VMCI_INTR_TYPE_MSIX)
                pci_disable_msix(pdev);
        else if (vmci_dev->intr_type == VMCI_INTR_TYPE_MSI)
                pci_disable_msi(pdev);

        vmci_err = vmci_event_unsubscribe(ctx_update_sub_id);
        if (vmci_err < VMCI_SUCCESS)
                dev_warn(&pdev->dev,
                         "Failed to unsubscribe from event (type=%d) with subscriber (ID=0x%x): %d\n",
                         VMCI_EVENT_CTX_ID_UPDATE, ctx_update_sub_id, vmci_err);

err_remove_bitmap:
        if (vmci_dev->notification_bitmap) {
                iowrite32(VMCI_CONTROL_RESET,
                          vmci_dev->iobase + VMCI_CONTROL_ADDR);
                dma_free_coherent(&pdev->dev, PAGE_SIZE,
                                  vmci_dev->notification_bitmap,
                                  vmci_dev->notification_base);
        }

err_remove_vmci_dev_g:
        spin_lock_irq(&vmci_dev_spinlock);
        vmci_pdev = NULL;
        vmci_dev_g = NULL;
        spin_unlock_irq(&vmci_dev_spinlock);

err_free_data_buffer:
        vfree(vmci_dev->data_buffer);

        /* The rest are managed resources and will be freed by PCI core */
        return error;
}

static void vmci_guest_remove_device(struct pci_dev *pdev)
{
        struct vmci_guest_device *vmci_dev = pci_get_drvdata(pdev);
        int vmci_err;

        dev_dbg(&pdev->dev, "Removing device\n");

        atomic_dec(&vmci_num_guest_devices);

        vmci_qp_guest_endpoints_exit();

        vmci_err = vmci_event_unsubscribe(ctx_update_sub_id);
        if (vmci_err < VMCI_SUCCESS)
                dev_warn(&pdev->dev,
                         "Failed to unsubscribe from event (type=%d) with subscriber (ID=0x%x): %d\n",
                         VMCI_EVENT_CTX_ID_UPDATE, ctx_update_sub_id, vmci_err);

        spin_lock_irq(&vmci_dev_spinlock);
        vmci_dev_g = NULL;
        vmci_pdev = NULL;
        spin_unlock_irq(&vmci_dev_spinlock);

        dev_dbg(&pdev->dev, "Resetting vmci device\n");
        iowrite32(VMCI_CONTROL_RESET, vmci_dev->iobase + VMCI_CONTROL_ADDR);

        /*
         * Free IRQ and then disable MSI/MSI-X as appropriate.  For
         * MSI-X, we might have multiple vectors, each with their own
         * IRQ, which we must free too.
         */
        free_irq(vmci_dev->irq, vmci_dev);
        if (vmci_dev->intr_type == VMCI_INTR_TYPE_MSIX) {
                if (vmci_dev->exclusive_vectors)
                        free_irq(vmci_dev->msix_entries[1].vector, vmci_dev);
                pci_disable_msix(pdev);
        } else if (vmci_dev->intr_type == VMCI_INTR_TYPE_MSI) {
                pci_disable_msi(pdev);
        }

        tasklet_kill(&vmci_dev->datagram_tasklet);
        tasklet_kill(&vmci_dev->bm_tasklet);

        if (vmci_dev->notification_bitmap) {
                /*
                 * The device reset above cleared the bitmap state of the
                 * device, so we can safely free it here.
                 */

                dma_free_coherent(&pdev->dev, PAGE_SIZE,
                                  vmci_dev->notification_bitmap,
                                  vmci_dev->notification_base);
        }

        vfree(vmci_dev->data_buffer);

        /* The rest are managed resources and will be freed by PCI core */
}

static const struct pci_device_id vmci_ids[] = {
        { PCI_DEVICE(PCI_VENDOR_ID_VMWARE, PCI_DEVICE_ID_VMWARE_VMCI), },
        { 0 },
};
MODULE_DEVICE_TABLE(pci, vmci_ids);

static struct pci_driver vmci_guest_driver = {
        .name           = KBUILD_MODNAME,
        .id_table       = vmci_ids,
        .probe          = vmci_guest_probe_device,
        .remove         = vmci_guest_remove_device,
};

int __init vmci_guest_init(void)
{
        return pci_register_driver(&vmci_guest_driver);
}

void __exit vmci_guest_exit(void)
{
        pci_unregister_driver(&vmci_guest_driver);
}