/* SPDX-License-Identifier: (GPL-2.0 OR CDDL-1.0) */
/*
 * vboxguest core guest-device handling code, VBoxGuest.cpp in upstream svn.
 *
 * Copyright (C) 2007-2016 Oracle Corporation
 */

#include <linux/device.h>
#include <linux/io.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/sizes.h>
#include <linux/slab.h>
#include <linux/vbox_err.h>
#include <linux/vbox_utils.h>
#include <linux/vmalloc.h>
#include "vboxguest_core.h"
#include "vboxguest_version.h"

/* Get the pointer to the first HGCM parameter. */
#define VBG_IOCTL_HGCM_CALL_PARMS(a) \
        ((struct vmmdev_hgcm_function_parameter *)( \
                (u8 *)(a) + sizeof(struct vbg_ioctl_hgcm_call)))
/* Get the pointer to the first HGCM parameter in a 32-bit request. */
#define VBG_IOCTL_HGCM_CALL_PARMS32(a) \
        ((struct vmmdev_hgcm_function_parameter32 *)( \
                (u8 *)(a) + sizeof(struct vbg_ioctl_hgcm_call)))

#define GUEST_MAPPINGS_TRIES    5

#define VBG_KERNEL_REQUEST \
        (VMMDEV_REQUESTOR_KERNEL | VMMDEV_REQUESTOR_USR_DRV | \
         VMMDEV_REQUESTOR_CON_DONT_KNOW | VMMDEV_REQUESTOR_TRUST_NOT_GIVEN)

/**
 * vbg_guest_mappings_init - Reserves memory in which the VMM can
 *      relocate any guest mappings that are floating around.
 * @gdev:               The Guest extension device.
 *
 * This operation is a little bit tricky since the VMM might not accept
 * just any address because of address clashes between the three contexts
 * it operates in, so we try several times.
 *
 * Failure to reserve the guest mappings is ignored.
 */
static void vbg_guest_mappings_init(struct vbg_dev *gdev)
{
        struct vmmdev_hypervisorinfo *req;
        void *guest_mappings[GUEST_MAPPINGS_TRIES];
        struct page **pages = NULL;
        u32 size, hypervisor_size;
        int i, rc;

        /* Query the required space. */
        req = vbg_req_alloc(sizeof(*req), VMMDEVREQ_GET_HYPERVISOR_INFO,
                            VBG_KERNEL_REQUEST);
        if (!req)
                return;

        req->hypervisor_start = 0;
        req->hypervisor_size = 0;
        rc = vbg_req_perform(gdev, req);
        if (rc < 0)
                goto out;

        /*
         * The VMM will report back if there is nothing it wants to map, like
         * for instance in VT-x and AMD-V mode.
         */
        if (req->hypervisor_size == 0)
                goto out;

        hypervisor_size = req->hypervisor_size;
        /* Add 4M so that we can align the vmap to 4MiB as the host requires. */
        size = PAGE_ALIGN(req->hypervisor_size) + SZ_4M;

        pages = kmalloc_objs(*pages, size >> PAGE_SHIFT);
        if (!pages)
                goto out;

        gdev->guest_mappings_dummy_page = alloc_page(GFP_HIGHUSER);
        if (!gdev->guest_mappings_dummy_page)
                goto out;

        for (i = 0; i < (size >> PAGE_SHIFT); i++)
                pages[i] = gdev->guest_mappings_dummy_page;

        /*
         * Try several times, the VMM might not accept some addresses because
         * of address clashes between the three contexts.
         */
        for (i = 0; i < GUEST_MAPPINGS_TRIES; i++) {
                guest_mappings[i] = vmap(pages, (size >> PAGE_SHIFT),
                                         VM_MAP, PAGE_KERNEL_RO);
                if (!guest_mappings[i])
                        break;

                req->header.request_type = VMMDEVREQ_SET_HYPERVISOR_INFO;
                req->header.rc = VERR_INTERNAL_ERROR;
                req->hypervisor_size = hypervisor_size;
                req->hypervisor_start =
                        (unsigned long)PTR_ALIGN(guest_mappings[i], SZ_4M);

                rc = vbg_req_perform(gdev, req);
                if (rc >= 0) {
                        gdev->guest_mappings = guest_mappings[i];
                        break;
                }
        }

        /* Free vmap's from failed attempts. */
        while (--i >= 0)
                vunmap(guest_mappings[i]);

        /* On failure free the dummy-page backing the vmap */
        if (!gdev->guest_mappings) {
                __free_page(gdev->guest_mappings_dummy_page);
                gdev->guest_mappings_dummy_page = NULL;
        }

out:
        vbg_req_free(req, sizeof(*req));
        kfree(pages);
}

/**
 * vbg_guest_mappings_exit - Undo what vbg_guest_mappings_init did.
 *
 * @gdev:               The Guest extension device.
 */
static void vbg_guest_mappings_exit(struct vbg_dev *gdev)
{
        struct vmmdev_hypervisorinfo *req;
        int rc;

        if (!gdev->guest_mappings)
                return;

        /*
         * Tell the host that we're going to free the memory we reserved for
         * it, the free it up. (Leak the memory if anything goes wrong here.)
         */
        req = vbg_req_alloc(sizeof(*req), VMMDEVREQ_SET_HYPERVISOR_INFO,
                            VBG_KERNEL_REQUEST);
        if (!req)
                return;

        req->hypervisor_start = 0;
        req->hypervisor_size = 0;

        rc = vbg_req_perform(gdev, req);

        vbg_req_free(req, sizeof(*req));

        if (rc < 0) {
                vbg_err("%s error: %d\n", __func__, rc);
                return;
        }

        vunmap(gdev->guest_mappings);
        gdev->guest_mappings = NULL;

        __free_page(gdev->guest_mappings_dummy_page);
        gdev->guest_mappings_dummy_page = NULL;
}

/**
 * vbg_report_guest_info - Report the guest information to the host.
 * @gdev:               The Guest extension device.
 *
 * Return: %0 or negative errno value.
 */
static int vbg_report_guest_info(struct vbg_dev *gdev)
{
        /*
         * Allocate and fill in the two guest info reports.
         */
        struct vmmdev_guest_info *req1 = NULL;
        struct vmmdev_guest_info2 *req2 = NULL;
        int rc, ret = -ENOMEM;

        req1 = vbg_req_alloc(sizeof(*req1), VMMDEVREQ_REPORT_GUEST_INFO,
                             VBG_KERNEL_REQUEST);
        req2 = vbg_req_alloc(sizeof(*req2), VMMDEVREQ_REPORT_GUEST_INFO2,
                             VBG_KERNEL_REQUEST);
        if (!req1 || !req2)
                goto out_free;

        req1->interface_version = VMMDEV_VERSION;
        req1->os_type = VMMDEV_OSTYPE_LINUX26;
#if __BITS_PER_LONG == 64
        req1->os_type |= VMMDEV_OSTYPE_X64;
#endif

        req2->additions_major = VBG_VERSION_MAJOR;
        req2->additions_minor = VBG_VERSION_MINOR;
        req2->additions_build = VBG_VERSION_BUILD;
        req2->additions_revision = VBG_SVN_REV;
        req2->additions_features =
                VMMDEV_GUEST_INFO2_ADDITIONS_FEATURES_REQUESTOR_INFO;
        strscpy(req2->name, VBG_VERSION_STRING,
                sizeof(req2->name));

        /*
         * There are two protocols here:
         *      1. INFO2 + INFO1. Supported by >=3.2.51.
         *      2. INFO1 and optionally INFO2. The old protocol.
         *
         * We try protocol 2 first.  It will fail with VERR_NOT_SUPPORTED
         * if not supported by the VMMDev (message ordering requirement).
         */
        rc = vbg_req_perform(gdev, req2);
        if (rc >= 0) {
                rc = vbg_req_perform(gdev, req1);
        } else if (rc == VERR_NOT_SUPPORTED || rc == VERR_NOT_IMPLEMENTED) {
                rc = vbg_req_perform(gdev, req1);
                if (rc >= 0) {
                        rc = vbg_req_perform(gdev, req2);
                        if (rc == VERR_NOT_IMPLEMENTED)
                                rc = VINF_SUCCESS;
                }
        }
        ret = vbg_status_code_to_errno(rc);

out_free:
        vbg_req_free(req2, sizeof(*req2));
        vbg_req_free(req1, sizeof(*req1));
        return ret;
}

/**
 * vbg_report_driver_status - Report the guest driver status to the host.
 * @gdev:               The Guest extension device.
 * @active:             Flag whether the driver is now active or not.
 *
 * Return: 0 or negative errno value.
 */
static int vbg_report_driver_status(struct vbg_dev *gdev, bool active)
{
        struct vmmdev_guest_status *req;
        int rc;

        req = vbg_req_alloc(sizeof(*req), VMMDEVREQ_REPORT_GUEST_STATUS,
                            VBG_KERNEL_REQUEST);
        if (!req)
                return -ENOMEM;

        req->facility = VBOXGUEST_FACILITY_TYPE_VBOXGUEST_DRIVER;
        if (active)
                req->status = VBOXGUEST_FACILITY_STATUS_ACTIVE;
        else
                req->status = VBOXGUEST_FACILITY_STATUS_INACTIVE;
        req->flags = 0;

        rc = vbg_req_perform(gdev, req);
        if (rc == VERR_NOT_IMPLEMENTED) /* Compatibility with older hosts. */
                rc = VINF_SUCCESS;

        vbg_req_free(req, sizeof(*req));

        return vbg_status_code_to_errno(rc);
}

/**
 * vbg_balloon_inflate - Inflate the balloon by one chunk. The caller
 * owns the balloon mutex.
 * @gdev:               The Guest extension device.
 * @chunk_idx:          Index of the chunk.
 *
 * Return: %0 or negative errno value.
 */
static int vbg_balloon_inflate(struct vbg_dev *gdev, u32 chunk_idx)
{
        struct vmmdev_memballoon_change *req = gdev->mem_balloon.change_req;
        struct page **pages;
        int i, rc, ret;

        pages = kmalloc_objs(*pages, VMMDEV_MEMORY_BALLOON_CHUNK_PAGES,
                             GFP_KERNEL | __GFP_NOWARN);
        if (!pages)
                return -ENOMEM;

        req->header.size = sizeof(*req);
        req->inflate = true;
        req->pages = VMMDEV_MEMORY_BALLOON_CHUNK_PAGES;

        for (i = 0; i < VMMDEV_MEMORY_BALLOON_CHUNK_PAGES; i++) {
                pages[i] = alloc_page(GFP_KERNEL | __GFP_NOWARN);
                if (!pages[i]) {
                        ret = -ENOMEM;
                        goto out_error;
                }

                req->phys_page[i] = page_to_phys(pages[i]);
        }

        rc = vbg_req_perform(gdev, req);
        if (rc < 0) {
                vbg_err("%s error, rc: %d\n", __func__, rc);
                ret = vbg_status_code_to_errno(rc);
                goto out_error;
        }

        gdev->mem_balloon.pages[chunk_idx] = pages;

        return 0;

out_error:
        while (--i >= 0)
                __free_page(pages[i]);
        kfree(pages);

        return ret;
}

/**
 * vbg_balloon_deflate - Deflate the balloon by one chunk. The caller
 * owns the balloon mutex.
 * @gdev:               The Guest extension device.
 * @chunk_idx:          Index of the chunk.
 *
 * Return: %0 or negative errno value.
 */
static int vbg_balloon_deflate(struct vbg_dev *gdev, u32 chunk_idx)
{
        struct vmmdev_memballoon_change *req = gdev->mem_balloon.change_req;
        struct page **pages = gdev->mem_balloon.pages[chunk_idx];
        int i, rc;

        req->header.size = sizeof(*req);
        req->inflate = false;
        req->pages = VMMDEV_MEMORY_BALLOON_CHUNK_PAGES;

        for (i = 0; i < VMMDEV_MEMORY_BALLOON_CHUNK_PAGES; i++)
                req->phys_page[i] = page_to_phys(pages[i]);

        rc = vbg_req_perform(gdev, req);
        if (rc < 0) {
                vbg_err("%s error, rc: %d\n", __func__, rc);
                return vbg_status_code_to_errno(rc);
        }

        for (i = 0; i < VMMDEV_MEMORY_BALLOON_CHUNK_PAGES; i++)
                __free_page(pages[i]);
        kfree(pages);
        gdev->mem_balloon.pages[chunk_idx] = NULL;

        return 0;
}

/*
 * Respond to VMMDEV_EVENT_BALLOON_CHANGE_REQUEST events, query the size
 * the host wants the balloon to be and adjust accordingly.
 */
static void vbg_balloon_work(struct work_struct *work)
{
        struct vbg_dev *gdev =
                container_of(work, struct vbg_dev, mem_balloon.work);
        struct vmmdev_memballoon_info *req = gdev->mem_balloon.get_req;
        u32 i, chunks;
        int rc, ret;

        /*
         * Setting this bit means that we request the value from the host and
         * change the guest memory balloon according to the returned value.
         */
        req->event_ack = VMMDEV_EVENT_BALLOON_CHANGE_REQUEST;
        rc = vbg_req_perform(gdev, req);
        if (rc < 0) {
                vbg_err("%s error, rc: %d)\n", __func__, rc);
                return;
        }

        /*
         * The host always returns the same maximum amount of chunks, so
         * we do this once.
         */
        if (!gdev->mem_balloon.max_chunks) {
                gdev->mem_balloon.pages =
                        devm_kcalloc(gdev->dev, req->phys_mem_chunks,
                                     sizeof(struct page **), GFP_KERNEL);
                if (!gdev->mem_balloon.pages)
                        return;

                gdev->mem_balloon.max_chunks = req->phys_mem_chunks;
        }

        chunks = req->balloon_chunks;
        if (chunks > gdev->mem_balloon.max_chunks) {
                vbg_err("%s: illegal balloon size %u (max=%u)\n",
                        __func__, chunks, gdev->mem_balloon.max_chunks);
                return;
        }

        if (chunks > gdev->mem_balloon.chunks) {
                /* inflate */
                for (i = gdev->mem_balloon.chunks; i < chunks; i++) {
                        ret = vbg_balloon_inflate(gdev, i);
                        if (ret < 0)
                                return;

                        gdev->mem_balloon.chunks++;
                }
        } else {
                /* deflate */
                for (i = gdev->mem_balloon.chunks; i-- > chunks;) {
                        ret = vbg_balloon_deflate(gdev, i);
                        if (ret < 0)
                                return;

                        gdev->mem_balloon.chunks--;
                }
        }
}

/*
 * Callback for heartbeat timer.
 */
static void vbg_heartbeat_timer(struct timer_list *t)
{
        struct vbg_dev *gdev = timer_container_of(gdev, t, heartbeat_timer);

        vbg_req_perform(gdev, gdev->guest_heartbeat_req);
        mod_timer(&gdev->heartbeat_timer,
                  msecs_to_jiffies(gdev->heartbeat_interval_ms));
}

/**
 * vbg_heartbeat_host_config - Configure the host to check guest's heartbeat
 *      and get heartbeat interval from the host.
 * @gdev:               The Guest extension device.
 * @enabled:            Set true to enable guest heartbeat checks on host.
 *
 * Return: %0 or negative errno value.
 */
static int vbg_heartbeat_host_config(struct vbg_dev *gdev, bool enabled)
{
        struct vmmdev_heartbeat *req;
        int rc;

        req = vbg_req_alloc(sizeof(*req), VMMDEVREQ_HEARTBEAT_CONFIGURE,
                            VBG_KERNEL_REQUEST);
        if (!req)
                return -ENOMEM;

        req->enabled = enabled;
        req->interval_ns = 0;
        rc = vbg_req_perform(gdev, req);
        do_div(req->interval_ns, 1000000); /* ns -> ms */
        gdev->heartbeat_interval_ms = req->interval_ns;
        vbg_req_free(req, sizeof(*req));

        return vbg_status_code_to_errno(rc);
}

/**
 * vbg_heartbeat_init - Initializes the heartbeat timer. This feature
 * may be disabled by the host.
 * @gdev:               The Guest extension device.
 *
 * Return: %0 or negative errno value.
 */
static int vbg_heartbeat_init(struct vbg_dev *gdev)
{
        int ret;

        /* Make sure that heartbeat checking is disabled if we fail. */
        ret = vbg_heartbeat_host_config(gdev, false);
        if (ret < 0)
                return ret;

        ret = vbg_heartbeat_host_config(gdev, true);
        if (ret < 0)
                return ret;

        gdev->guest_heartbeat_req = vbg_req_alloc(
                                        sizeof(*gdev->guest_heartbeat_req),
                                        VMMDEVREQ_GUEST_HEARTBEAT,
                                        VBG_KERNEL_REQUEST);
        if (!gdev->guest_heartbeat_req)
                return -ENOMEM;

        vbg_info("%s: Setting up heartbeat to trigger every %d milliseconds\n",
                 __func__, gdev->heartbeat_interval_ms);
        mod_timer(&gdev->heartbeat_timer, 0);

        return 0;
}

/**
 * vbg_heartbeat_exit - Cleanup heartbeat code, stop HB timer and disable
 *      host heartbeat checking.
 * @gdev:               The Guest extension device.
 */
static void vbg_heartbeat_exit(struct vbg_dev *gdev)
{
        timer_delete_sync(&gdev->heartbeat_timer);
        vbg_heartbeat_host_config(gdev, false);
        vbg_req_free(gdev->guest_heartbeat_req,
                     sizeof(*gdev->guest_heartbeat_req));
}

/**
 * vbg_track_bit_usage - Applies a change to the bit usage tracker.
 * @tracker:            The bit usage tracker.
 * @changed:            The bits to change.
 * @previous:           The previous value of the bits.
 *
 * Return: %true if the mask changed, %false if not.
 */
static bool vbg_track_bit_usage(struct vbg_bit_usage_tracker *tracker,
                                u32 changed, u32 previous)
{
        bool global_change = false;

        while (changed) {
                u32 bit = ffs(changed) - 1;
                u32 bitmask = BIT(bit);

                if (bitmask & previous) {
                        tracker->per_bit_usage[bit] -= 1;
                        if (tracker->per_bit_usage[bit] == 0) {
                                global_change = true;
                                tracker->mask &= ~bitmask;
                        }
                } else {
                        tracker->per_bit_usage[bit] += 1;
                        if (tracker->per_bit_usage[bit] == 1) {
                                global_change = true;
                                tracker->mask |= bitmask;
                        }
                }

                changed &= ~bitmask;
        }

        return global_change;
}

/**
 * vbg_reset_host_event_filter - Init and termination worker for
 *      resetting the (host) event filter on the host
 * @gdev:                  The Guest extension device.
 * @fixed_events:          Fixed events (init time).
 *
 * Return: %0 or negative errno value.
 */
static int vbg_reset_host_event_filter(struct vbg_dev *gdev,
                                       u32 fixed_events)
{
        struct vmmdev_mask *req;
        int rc;

        req = vbg_req_alloc(sizeof(*req), VMMDEVREQ_CTL_GUEST_FILTER_MASK,
                            VBG_KERNEL_REQUEST);
        if (!req)
                return -ENOMEM;

        req->not_mask = U32_MAX & ~fixed_events;
        req->or_mask = fixed_events;
        rc = vbg_req_perform(gdev, req);
        if (rc < 0)
                vbg_err("%s error, rc: %d\n", __func__, rc);

        vbg_req_free(req, sizeof(*req));
        return vbg_status_code_to_errno(rc);
}

/**
 * vbg_set_session_event_filter - Changes the event filter mask for the
 *      given session.
 * @gdev:                       The Guest extension device.
 * @session:                    The session.
 * @or_mask:                    The events to add.
 * @not_mask:                   The events to remove.
 * @session_termination:        Set if we're called by the session cleanup code.
 *                              This tweaks the error handling so we perform
 *                              proper session cleanup even if the host
 *                              misbehaves.
 *
 * This is called in response to VBG_IOCTL_CHANGE_FILTER_MASK as well as to
 * do session cleanup. Takes the session mutex.
 *
 * Return: 0 or negative errno value.
 */
static int vbg_set_session_event_filter(struct vbg_dev *gdev,
                                        struct vbg_session *session,
                                        u32 or_mask, u32 not_mask,
                                        bool session_termination)
{
        struct vmmdev_mask *req;
        u32 changed, previous;
        int rc, ret = 0;

        /*
         * Allocate a request buffer before taking the spinlock, when
         * the session is being terminated the requestor is the kernel,
         * as we're cleaning up.
         */
        req = vbg_req_alloc(sizeof(*req), VMMDEVREQ_CTL_GUEST_FILTER_MASK,
                            session_termination ? VBG_KERNEL_REQUEST :
                                                  session->requestor);
        if (!req) {
                if (!session_termination)
                        return -ENOMEM;
                /* Ignore allocation failure, we must do session cleanup. */
        }

        mutex_lock(&gdev->session_mutex);

        /* Apply the changes to the session mask. */
        previous = session->event_filter;
        session->event_filter |= or_mask;
        session->event_filter &= ~not_mask;

        /* If anything actually changed, update the global usage counters. */
        changed = previous ^ session->event_filter;
        if (!changed)
                goto out;

        vbg_track_bit_usage(&gdev->event_filter_tracker, changed, previous);
        or_mask = gdev->fixed_events | gdev->event_filter_tracker.mask;

        if (gdev->event_filter_host == or_mask || !req)
                goto out;

        gdev->event_filter_host = or_mask;
        req->or_mask = or_mask;
        req->not_mask = ~or_mask;
        rc = vbg_req_perform(gdev, req);
        if (rc < 0) {
                ret = vbg_status_code_to_errno(rc);

                /* Failed, roll back (unless it's session termination time). */
                gdev->event_filter_host = U32_MAX;
                if (session_termination)
                        goto out;

                vbg_track_bit_usage(&gdev->event_filter_tracker, changed,
                                    session->event_filter);
                session->event_filter = previous;
        }

out:
        mutex_unlock(&gdev->session_mutex);
        vbg_req_free(req, sizeof(*req));

        return ret;
}

/**
 * vbg_reset_host_capabilities - Init and termination worker for set
 *      guest capabilities to zero on the host.
 * @gdev:               The Guest extension device.
 *
 * Return: %0 or negative errno value.
 */
static int vbg_reset_host_capabilities(struct vbg_dev *gdev)
{
        struct vmmdev_mask *req;
        int rc;

        req = vbg_req_alloc(sizeof(*req), VMMDEVREQ_SET_GUEST_CAPABILITIES,
                            VBG_KERNEL_REQUEST);
        if (!req)
                return -ENOMEM;

        req->not_mask = U32_MAX;
        req->or_mask = 0;
        rc = vbg_req_perform(gdev, req);
        if (rc < 0)
                vbg_err("%s error, rc: %d\n", __func__, rc);

        vbg_req_free(req, sizeof(*req));
        return vbg_status_code_to_errno(rc);
}

/**
 * vbg_set_host_capabilities - Set guest capabilities on the host.
 * @gdev:                       The Guest extension device.
 * @session:                    The session.
 * @session_termination:        Set if we're called by the session cleanup code.
 *
 * Must be called with gdev->session_mutex hold.
 *
 * Return: %0 or negative errno value.
 */
static int vbg_set_host_capabilities(struct vbg_dev *gdev,
                                     struct vbg_session *session,
                                     bool session_termination)
{
        struct vmmdev_mask *req;
        u32 caps;
        int rc;

        WARN_ON(!mutex_is_locked(&gdev->session_mutex));

        caps = gdev->acquired_guest_caps | gdev->set_guest_caps_tracker.mask;

        if (gdev->guest_caps_host == caps)
                return 0;

        /* On termination the requestor is the kernel, as we're cleaning up. */
        req = vbg_req_alloc(sizeof(*req), VMMDEVREQ_SET_GUEST_CAPABILITIES,
                            session_termination ? VBG_KERNEL_REQUEST :
                                                  session->requestor);
        if (!req) {
                gdev->guest_caps_host = U32_MAX;
                return -ENOMEM;
        }

        req->or_mask = caps;
        req->not_mask = ~caps;
        rc = vbg_req_perform(gdev, req);
        vbg_req_free(req, sizeof(*req));

        gdev->guest_caps_host = (rc >= 0) ? caps : U32_MAX;

        return vbg_status_code_to_errno(rc);
}

/**
 * vbg_acquire_session_capabilities - Acquire (get exclusive access)
 *      guest capabilities for a session.
 * @gdev:                       The Guest extension device.
 * @session:                    The session.
 * @flags:                      Flags (VBGL_IOC_AGC_FLAGS_XXX).
 * @or_mask:                    The capabilities to add.
 * @not_mask:                   The capabilities to remove.
 * @session_termination:        Set if we're called by the session cleanup code.
 *                              This tweaks the error handling so we perform
 *                              proper session cleanup even if the host
 *                              misbehaves.
 *
 * Takes the session mutex.
 *
 * Return: %0 or negative errno value.
 */
static int vbg_acquire_session_capabilities(struct vbg_dev *gdev,
                                            struct vbg_session *session,
                                            u32 or_mask, u32 not_mask,
                                            u32 flags, bool session_termination)
{
        unsigned long irqflags;
        bool wakeup = false;
        int ret = 0;

        mutex_lock(&gdev->session_mutex);

        if (gdev->set_guest_caps_tracker.mask & or_mask) {
                vbg_err("%s error: cannot acquire caps which are currently set\n",
                        __func__);
                ret = -EINVAL;
                goto out;
        }

        /*
         * Mark any caps in the or_mask as now being in acquire-mode. Note
         * once caps are in acquire_mode they always stay in this mode.
         * This impacts event handling, so we take the event-lock.
         */
        spin_lock_irqsave(&gdev->event_spinlock, irqflags);
        gdev->acquire_mode_guest_caps |= or_mask;
        spin_unlock_irqrestore(&gdev->event_spinlock, irqflags);

        /* If we only have to switch the caps to acquire mode, we're done. */
        if (flags & VBGL_IOC_AGC_FLAGS_CONFIG_ACQUIRE_MODE)
                goto out;

        not_mask &= ~or_mask; /* or_mask takes priority over not_mask */
        not_mask &= session->acquired_guest_caps;
        or_mask &= ~session->acquired_guest_caps;

        if (or_mask == 0 && not_mask == 0)
                goto out;

        if (gdev->acquired_guest_caps & or_mask) {
                ret = -EBUSY;
                goto out;
        }

        gdev->acquired_guest_caps |= or_mask;
        gdev->acquired_guest_caps &= ~not_mask;
        /* session->acquired_guest_caps impacts event handling, take the lock */
        spin_lock_irqsave(&gdev->event_spinlock, irqflags);
        session->acquired_guest_caps |= or_mask;
        session->acquired_guest_caps &= ~not_mask;
        spin_unlock_irqrestore(&gdev->event_spinlock, irqflags);

        ret = vbg_set_host_capabilities(gdev, session, session_termination);
        /* Roll back on failure, unless it's session termination time. */
        if (ret < 0 && !session_termination) {
                gdev->acquired_guest_caps &= ~or_mask;
                gdev->acquired_guest_caps |= not_mask;
                spin_lock_irqsave(&gdev->event_spinlock, irqflags);
                session->acquired_guest_caps &= ~or_mask;
                session->acquired_guest_caps |= not_mask;
                spin_unlock_irqrestore(&gdev->event_spinlock, irqflags);
        }

        /*
         * If we added a capability, check if that means some other thread in
         * our session should be unblocked because there are events pending
         * (the result of vbg_get_allowed_event_mask_for_session() may change).
         *
         * HACK ALERT! When the seamless support capability is added we generate
         *      a seamless change event so that the ring-3 client can sync with
         *      the seamless state.
         */
        if (ret == 0 && or_mask != 0) {
                spin_lock_irqsave(&gdev->event_spinlock, irqflags);

                if (or_mask & VMMDEV_GUEST_SUPPORTS_SEAMLESS)
                        gdev->pending_events |=
                                VMMDEV_EVENT_SEAMLESS_MODE_CHANGE_REQUEST;

                if (gdev->pending_events)
                        wakeup = true;

                spin_unlock_irqrestore(&gdev->event_spinlock, irqflags);

                if (wakeup)
                        wake_up(&gdev->event_wq);
        }

out:
        mutex_unlock(&gdev->session_mutex);

        return ret;
}

/**
 * vbg_set_session_capabilities - Sets the guest capabilities for a
 *      session. Takes the session mutex.
 * @gdev:                       The Guest extension device.
 * @session:                    The session.
 * @or_mask:                    The capabilities to add.
 * @not_mask:                   The capabilities to remove.
 * @session_termination:        Set if we're called by the session cleanup code.
 *                              This tweaks the error handling so we perform
 *                              proper session cleanup even if the host
 *                              misbehaves.
 *
 * Return: %0 or negative errno value.
 */
static int vbg_set_session_capabilities(struct vbg_dev *gdev,
                                        struct vbg_session *session,
                                        u32 or_mask, u32 not_mask,
                                        bool session_termination)
{
        u32 changed, previous;
        int ret = 0;

        mutex_lock(&gdev->session_mutex);

        if (gdev->acquire_mode_guest_caps & or_mask) {
                vbg_err("%s error: cannot set caps which are in acquire_mode\n",
                        __func__);
                ret = -EBUSY;
                goto out;
        }

        /* Apply the changes to the session mask. */
        previous = session->set_guest_caps;
        session->set_guest_caps |= or_mask;
        session->set_guest_caps &= ~not_mask;

        /* If anything actually changed, update the global usage counters. */
        changed = previous ^ session->set_guest_caps;
        if (!changed)
                goto out;

        vbg_track_bit_usage(&gdev->set_guest_caps_tracker, changed, previous);

        ret = vbg_set_host_capabilities(gdev, session, session_termination);
        /* Roll back on failure, unless it's session termination time. */
        if (ret < 0 && !session_termination) {
                vbg_track_bit_usage(&gdev->set_guest_caps_tracker, changed,
                                    session->set_guest_caps);
                session->set_guest_caps = previous;
        }

out:
        mutex_unlock(&gdev->session_mutex);

        return ret;
}

/**
 * vbg_query_host_version - get the host feature mask and version information.
 * @gdev:               The Guest extension device.
 *
 * Return: %0 or negative errno value.
 */
static int vbg_query_host_version(struct vbg_dev *gdev)
{
        struct vmmdev_host_version *req;
        int rc, ret;

        req = vbg_req_alloc(sizeof(*req), VMMDEVREQ_GET_HOST_VERSION,
                            VBG_KERNEL_REQUEST);
        if (!req)
                return -ENOMEM;

        rc = vbg_req_perform(gdev, req);
        ret = vbg_status_code_to_errno(rc);
        if (ret) {
                vbg_err("%s error: %d\n", __func__, rc);
                goto out;
        }

        snprintf(gdev->host_version, sizeof(gdev->host_version), "%u.%u.%ur%u",
                 req->major, req->minor, req->build, req->revision);
        gdev->host_features = req->features;

        vbg_info("vboxguest: host-version: %s %#x\n", gdev->host_version,
                 gdev->host_features);

        if (!(req->features & VMMDEV_HVF_HGCM_PHYS_PAGE_LIST)) {
                vbg_err("vboxguest: Error host too old (does not support page-lists)\n");
                ret = -ENODEV;
        }

out:
        vbg_req_free(req, sizeof(*req));
        return ret;
}

/**
 * vbg_core_init - Initializes the VBoxGuest device extension when the
 *      device driver is loaded.
 * @gdev:               The Guest extension device.
 * @fixed_events:       Events that will be enabled upon init and no client
 *                      will ever be allowed to mask.
 *
 * The native code locates the VMMDev on the PCI bus and retrieve
 * the MMIO and I/O port ranges, this function will take care of
 * mapping the MMIO memory (if present). Upon successful return
 * the native code should set up the interrupt handler.
 *
 * Return: %0 or negative errno value.
 */
int vbg_core_init(struct vbg_dev *gdev, u32 fixed_events)
{
        int ret = -ENOMEM;

        gdev->fixed_events = fixed_events | VMMDEV_EVENT_HGCM;
        gdev->event_filter_host = U32_MAX;      /* forces a report */
        gdev->guest_caps_host = U32_MAX;        /* forces a report */

        init_waitqueue_head(&gdev->event_wq);
        init_waitqueue_head(&gdev->hgcm_wq);
        spin_lock_init(&gdev->event_spinlock);
        mutex_init(&gdev->session_mutex);
        mutex_init(&gdev->cancel_req_mutex);
        timer_setup(&gdev->heartbeat_timer, vbg_heartbeat_timer, 0);
        INIT_WORK(&gdev->mem_balloon.work, vbg_balloon_work);

        gdev->mem_balloon.get_req =
                vbg_req_alloc(sizeof(*gdev->mem_balloon.get_req),
                              VMMDEVREQ_GET_MEMBALLOON_CHANGE_REQ,
                              VBG_KERNEL_REQUEST);
        gdev->mem_balloon.change_req =
                vbg_req_alloc(sizeof(*gdev->mem_balloon.change_req),
                              VMMDEVREQ_CHANGE_MEMBALLOON,
                              VBG_KERNEL_REQUEST);
        gdev->cancel_req =
                vbg_req_alloc(sizeof(*(gdev->cancel_req)),
                              VMMDEVREQ_HGCM_CANCEL2,
                              VBG_KERNEL_REQUEST);
        gdev->ack_events_req =
                vbg_req_alloc(sizeof(*gdev->ack_events_req),
                              VMMDEVREQ_ACKNOWLEDGE_EVENTS,
                              VBG_KERNEL_REQUEST);
        gdev->mouse_status_req =
                vbg_req_alloc(sizeof(*gdev->mouse_status_req),
                              VMMDEVREQ_GET_MOUSE_STATUS,
                              VBG_KERNEL_REQUEST);

        if (!gdev->mem_balloon.get_req || !gdev->mem_balloon.change_req ||
            !gdev->cancel_req || !gdev->ack_events_req ||
            !gdev->mouse_status_req)
                goto err_free_reqs;

        ret = vbg_query_host_version(gdev);
        if (ret)
                goto err_free_reqs;

        ret = vbg_report_guest_info(gdev);
        if (ret) {
                vbg_err("vboxguest: vbg_report_guest_info error: %d\n", ret);
                goto err_free_reqs;
        }

        ret = vbg_reset_host_event_filter(gdev, gdev->fixed_events);
        if (ret) {
                vbg_err("vboxguest: Error setting fixed event filter: %d\n",
                        ret);
                goto err_free_reqs;
        }

        ret = vbg_reset_host_capabilities(gdev);
        if (ret) {
                vbg_err("vboxguest: Error clearing guest capabilities: %d\n",
                        ret);
                goto err_free_reqs;
        }

        ret = vbg_core_set_mouse_status(gdev, 0);
        if (ret) {
                vbg_err("vboxguest: Error clearing mouse status: %d\n", ret);
                goto err_free_reqs;
        }

        /* These may fail without requiring the driver init to fail. */
        vbg_guest_mappings_init(gdev);
        vbg_heartbeat_init(gdev);

        /* All Done! */
        ret = vbg_report_driver_status(gdev, true);
        if (ret < 0)
                vbg_err("vboxguest: Error reporting driver status: %d\n", ret);

        return 0;

err_free_reqs:
        vbg_req_free(gdev->mouse_status_req,
                     sizeof(*gdev->mouse_status_req));
        vbg_req_free(gdev->ack_events_req,
                     sizeof(*gdev->ack_events_req));
        vbg_req_free(gdev->cancel_req,
                     sizeof(*gdev->cancel_req));
        vbg_req_free(gdev->mem_balloon.change_req,
                     sizeof(*gdev->mem_balloon.change_req));
        vbg_req_free(gdev->mem_balloon.get_req,
                     sizeof(*gdev->mem_balloon.get_req));
        return ret;
}

/**
 * vbg_core_exit - Call this on exit to clean-up vboxguest-core managed
 *      resources.
 * @gdev:               The Guest extension device.
 *
 * The native code should call this before the driver is loaded,
 * but don't call this on shutdown.
 */
void vbg_core_exit(struct vbg_dev *gdev)
{
        vbg_heartbeat_exit(gdev);
        vbg_guest_mappings_exit(gdev);

        /* Clear the host flags (mouse status etc). */
        vbg_reset_host_event_filter(gdev, 0);
        vbg_reset_host_capabilities(gdev);
        vbg_core_set_mouse_status(gdev, 0);

        vbg_req_free(gdev->mouse_status_req,
                     sizeof(*gdev->mouse_status_req));
        vbg_req_free(gdev->ack_events_req,
                     sizeof(*gdev->ack_events_req));
        vbg_req_free(gdev->cancel_req,
                     sizeof(*gdev->cancel_req));
        vbg_req_free(gdev->mem_balloon.change_req,
                     sizeof(*gdev->mem_balloon.change_req));
        vbg_req_free(gdev->mem_balloon.get_req,
                     sizeof(*gdev->mem_balloon.get_req));
}

/**
 * vbg_core_open_session - Creates a VBoxGuest user session.
 * @gdev:               The Guest extension device.
 * @requestor:          VMMDEV_REQUESTOR_* flags
 *
 * vboxguest_linux.c calls this when userspace opens the char-device.
 *
 * Return: A pointer to the new session or an ERR_PTR on error.
 */
struct vbg_session *vbg_core_open_session(struct vbg_dev *gdev, u32 requestor)
{
        struct vbg_session *session;

        session = kzalloc_obj(*session);
        if (!session)
                return ERR_PTR(-ENOMEM);

        session->gdev = gdev;
        session->requestor = requestor;

        return session;
}

/**
 * vbg_core_close_session - Closes a VBoxGuest session.
 * @session:            The session to close (and free).
 */
void vbg_core_close_session(struct vbg_session *session)
{
        struct vbg_dev *gdev = session->gdev;
        int i, rc;

        vbg_acquire_session_capabilities(gdev, session, 0, U32_MAX, 0, true);
        vbg_set_session_capabilities(gdev, session, 0, U32_MAX, true);
        vbg_set_session_event_filter(gdev, session, 0, U32_MAX, true);

        for (i = 0; i < ARRAY_SIZE(session->hgcm_client_ids); i++) {
                if (!session->hgcm_client_ids[i])
                        continue;

                /* requestor is kernel here, as we're cleaning up. */
                vbg_hgcm_disconnect(gdev, VBG_KERNEL_REQUEST,
                                    session->hgcm_client_ids[i], &rc);
        }

        kfree(session);
}

static int vbg_ioctl_chk(struct vbg_ioctl_hdr *hdr, size_t in_size,
                         size_t out_size)
{
        if (hdr->size_in  != (sizeof(*hdr) + in_size) ||
            hdr->size_out != (sizeof(*hdr) + out_size))
                return -EINVAL;

        return 0;
}

static int vbg_ioctl_driver_version_info(
        struct vbg_ioctl_driver_version_info *info)
{
        const u16 vbg_maj_version = VBG_IOC_VERSION >> 16;
        u16 min_maj_version, req_maj_version;

        if (vbg_ioctl_chk(&info->hdr, sizeof(info->u.in), sizeof(info->u.out)))
                return -EINVAL;

        req_maj_version = info->u.in.req_version >> 16;
        min_maj_version = info->u.in.min_version >> 16;

        if (info->u.in.min_version > info->u.in.req_version ||
            min_maj_version != req_maj_version)
                return -EINVAL;

        if (info->u.in.min_version <= VBG_IOC_VERSION &&
            min_maj_version == vbg_maj_version) {
                info->u.out.session_version = VBG_IOC_VERSION;
        } else {
                info->u.out.session_version = U32_MAX;
                info->hdr.rc = VERR_VERSION_MISMATCH;
        }

        info->u.out.driver_version  = VBG_IOC_VERSION;
        info->u.out.driver_revision = 0;
        info->u.out.reserved1      = 0;
        info->u.out.reserved2      = 0;

        return 0;
}

/* Must be called with the event_lock held */
static u32 vbg_get_allowed_event_mask_for_session(struct vbg_dev *gdev,
                                                  struct vbg_session *session)
{
        u32 acquire_mode_caps = gdev->acquire_mode_guest_caps;
        u32 session_acquired_caps = session->acquired_guest_caps;
        u32 allowed_events = VMMDEV_EVENT_VALID_EVENT_MASK;

        if ((acquire_mode_caps & VMMDEV_GUEST_SUPPORTS_GRAPHICS) &&
            !(session_acquired_caps & VMMDEV_GUEST_SUPPORTS_GRAPHICS))
                allowed_events &= ~VMMDEV_EVENT_DISPLAY_CHANGE_REQUEST;

        if ((acquire_mode_caps & VMMDEV_GUEST_SUPPORTS_SEAMLESS) &&
            !(session_acquired_caps & VMMDEV_GUEST_SUPPORTS_SEAMLESS))
                allowed_events &= ~VMMDEV_EVENT_SEAMLESS_MODE_CHANGE_REQUEST;

        return allowed_events;
}

static bool vbg_wait_event_cond(struct vbg_dev *gdev,
                                struct vbg_session *session,
                                u32 event_mask)
{
        unsigned long flags;
        bool wakeup;
        u32 events;

        spin_lock_irqsave(&gdev->event_spinlock, flags);

        events = gdev->pending_events & event_mask;
        events &= vbg_get_allowed_event_mask_for_session(gdev, session);
        wakeup = events || session->cancel_waiters;

        spin_unlock_irqrestore(&gdev->event_spinlock, flags);

        return wakeup;
}

/* Must be called with the event_lock held */
static u32 vbg_consume_events_locked(struct vbg_dev *gdev,
                                     struct vbg_session *session,
                                     u32 event_mask)
{
        u32 events = gdev->pending_events & event_mask;

        events &= vbg_get_allowed_event_mask_for_session(gdev, session);
        gdev->pending_events &= ~events;
        return events;
}

static int vbg_ioctl_wait_for_events(struct vbg_dev *gdev,
                                     struct vbg_session *session,
                                     struct vbg_ioctl_wait_for_events *wait)
{
        u32 timeout_ms = wait->u.in.timeout_ms;
        u32 event_mask = wait->u.in.events;
        unsigned long flags;
        long timeout;
        int ret = 0;

        if (vbg_ioctl_chk(&wait->hdr, sizeof(wait->u.in), sizeof(wait->u.out)))
                return -EINVAL;

        if (timeout_ms == U32_MAX)
                timeout = MAX_SCHEDULE_TIMEOUT;
        else
                timeout = msecs_to_jiffies(timeout_ms);

        wait->u.out.events = 0;
        do {
                timeout = wait_event_interruptible_timeout(
                                gdev->event_wq,
                                vbg_wait_event_cond(gdev, session, event_mask),
                                timeout);

                spin_lock_irqsave(&gdev->event_spinlock, flags);

                if (timeout < 0 || session->cancel_waiters) {
                        ret = -EINTR;
                } else if (timeout == 0) {
                        ret = -ETIMEDOUT;
                } else {
                        wait->u.out.events =
                           vbg_consume_events_locked(gdev, session, event_mask);
                }

                spin_unlock_irqrestore(&gdev->event_spinlock, flags);

                /*
                 * Someone else may have consumed the event(s) first, in
                 * which case we go back to waiting.
                 */
        } while (ret == 0 && wait->u.out.events == 0);

        return ret;
}

static int vbg_ioctl_interrupt_all_wait_events(struct vbg_dev *gdev,
                                               struct vbg_session *session,
                                               struct vbg_ioctl_hdr *hdr)
{
        unsigned long flags;

        if (hdr->size_in != sizeof(*hdr) || hdr->size_out != sizeof(*hdr))
                return -EINVAL;

        spin_lock_irqsave(&gdev->event_spinlock, flags);
        session->cancel_waiters = true;
        spin_unlock_irqrestore(&gdev->event_spinlock, flags);

        wake_up(&gdev->event_wq);

        return 0;
}

/**
 * vbg_req_allowed - Checks if the VMM request is allowed in the
 *      context of the given session.
 * @gdev:               The Guest extension device.
 * @session:            The calling session.
 * @req:                The request.
 *
 * Return: %0 or negative errno value.
 */
static int vbg_req_allowed(struct vbg_dev *gdev, struct vbg_session *session,
                           const struct vmmdev_request_header *req)
{
        const struct vmmdev_guest_status *guest_status;
        bool trusted_apps_only;

        switch (req->request_type) {
        /* Trusted users apps only. */
        case VMMDEVREQ_QUERY_CREDENTIALS:
        case VMMDEVREQ_REPORT_CREDENTIALS_JUDGEMENT:
        case VMMDEVREQ_REGISTER_SHARED_MODULE:
        case VMMDEVREQ_UNREGISTER_SHARED_MODULE:
        case VMMDEVREQ_WRITE_COREDUMP:
        case VMMDEVREQ_GET_CPU_HOTPLUG_REQ:
        case VMMDEVREQ_SET_CPU_HOTPLUG_STATUS:
        case VMMDEVREQ_CHECK_SHARED_MODULES:
        case VMMDEVREQ_GET_PAGE_SHARING_STATUS:
        case VMMDEVREQ_DEBUG_IS_PAGE_SHARED:
        case VMMDEVREQ_REPORT_GUEST_STATS:
        case VMMDEVREQ_REPORT_GUEST_USER_STATE:
        case VMMDEVREQ_GET_STATISTICS_CHANGE_REQ:
                trusted_apps_only = true;
                break;

        /* Anyone. */
        case VMMDEVREQ_GET_MOUSE_STATUS:
        case VMMDEVREQ_SET_MOUSE_STATUS:
        case VMMDEVREQ_SET_POINTER_SHAPE:
        case VMMDEVREQ_GET_HOST_VERSION:
        case VMMDEVREQ_IDLE:
        case VMMDEVREQ_GET_HOST_TIME:
        case VMMDEVREQ_SET_POWER_STATUS:
        case VMMDEVREQ_ACKNOWLEDGE_EVENTS:
        case VMMDEVREQ_CTL_GUEST_FILTER_MASK:
        case VMMDEVREQ_REPORT_GUEST_STATUS:
        case VMMDEVREQ_GET_DISPLAY_CHANGE_REQ:
        case VMMDEVREQ_VIDEMODE_SUPPORTED:
        case VMMDEVREQ_GET_HEIGHT_REDUCTION:
        case VMMDEVREQ_GET_DISPLAY_CHANGE_REQ2:
        case VMMDEVREQ_VIDEMODE_SUPPORTED2:
        case VMMDEVREQ_VIDEO_ACCEL_ENABLE:
        case VMMDEVREQ_VIDEO_ACCEL_FLUSH:
        case VMMDEVREQ_VIDEO_SET_VISIBLE_REGION:
        case VMMDEVREQ_VIDEO_UPDATE_MONITOR_POSITIONS:
        case VMMDEVREQ_GET_DISPLAY_CHANGE_REQEX:
        case VMMDEVREQ_GET_DISPLAY_CHANGE_REQ_MULTI:
        case VMMDEVREQ_GET_SEAMLESS_CHANGE_REQ:
        case VMMDEVREQ_GET_VRDPCHANGE_REQ:
        case VMMDEVREQ_LOG_STRING:
        case VMMDEVREQ_GET_SESSION_ID:
                trusted_apps_only = false;
                break;

        /* Depends on the request parameters... */
        case VMMDEVREQ_REPORT_GUEST_CAPABILITIES:
                guest_status = (const struct vmmdev_guest_status *)req;
                switch (guest_status->facility) {
                case VBOXGUEST_FACILITY_TYPE_ALL:
                case VBOXGUEST_FACILITY_TYPE_VBOXGUEST_DRIVER:
                        vbg_err("Denying userspace vmm report guest cap. call facility %#08x\n",
                                guest_status->facility);
                        return -EPERM;
                case VBOXGUEST_FACILITY_TYPE_VBOX_SERVICE:
                        trusted_apps_only = true;
                        break;
                case VBOXGUEST_FACILITY_TYPE_VBOX_TRAY_CLIENT:
                case VBOXGUEST_FACILITY_TYPE_SEAMLESS:
                case VBOXGUEST_FACILITY_TYPE_GRAPHICS:
                default:
                        trusted_apps_only = false;
                        break;
                }
                break;

        /* Anything else is not allowed. */
        default:
                vbg_err("Denying userspace vmm call type %#08x\n",
                        req->request_type);
                return -EPERM;
        }

        if (trusted_apps_only &&
            (session->requestor & VMMDEV_REQUESTOR_USER_DEVICE)) {
                vbg_err("Denying userspace vmm call type %#08x through vboxuser device node\n",
                        req->request_type);
                return -EPERM;
        }

        return 0;
}

static int vbg_ioctl_vmmrequest(struct vbg_dev *gdev,
                                struct vbg_session *session, void *data)
{
        struct vbg_ioctl_hdr *hdr = data;
        int ret;

        if (hdr->size_in != hdr->size_out)
                return -EINVAL;

        if (hdr->size_in > VMMDEV_MAX_VMMDEVREQ_SIZE)
                return -E2BIG;

        if (hdr->type == VBG_IOCTL_HDR_TYPE_DEFAULT)
                return -EINVAL;

        ret = vbg_req_allowed(gdev, session, data);
        if (ret < 0)
                return ret;

        vbg_req_perform(gdev, data);
        WARN_ON(hdr->rc == VINF_HGCM_ASYNC_EXECUTE);

        return 0;
}

static int vbg_ioctl_hgcm_connect(struct vbg_dev *gdev,
                                  struct vbg_session *session,
                                  struct vbg_ioctl_hgcm_connect *conn)
{
        u32 client_id;
        int i, ret;

        if (vbg_ioctl_chk(&conn->hdr, sizeof(conn->u.in), sizeof(conn->u.out)))
                return -EINVAL;

        /* Find a free place in the sessions clients array and claim it */
        mutex_lock(&gdev->session_mutex);
        for (i = 0; i < ARRAY_SIZE(session->hgcm_client_ids); i++) {
                if (!session->hgcm_client_ids[i]) {
                        session->hgcm_client_ids[i] = U32_MAX;
                        break;
                }
        }
        mutex_unlock(&gdev->session_mutex);

        if (i >= ARRAY_SIZE(session->hgcm_client_ids))
                return -EMFILE;

        ret = vbg_hgcm_connect(gdev, session->requestor, &conn->u.in.loc,
                               &client_id, &conn->hdr.rc);

        mutex_lock(&gdev->session_mutex);
        if (ret == 0 && conn->hdr.rc >= 0) {
                conn->u.out.client_id = client_id;
                session->hgcm_client_ids[i] = client_id;
        } else {
                conn->u.out.client_id = 0;
                session->hgcm_client_ids[i] = 0;
        }
        mutex_unlock(&gdev->session_mutex);

        return ret;
}

static int vbg_ioctl_hgcm_disconnect(struct vbg_dev *gdev,
                                     struct vbg_session *session,
                                     struct vbg_ioctl_hgcm_disconnect *disconn)
{
        u32 client_id;
        int i, ret;

        if (vbg_ioctl_chk(&disconn->hdr, sizeof(disconn->u.in), 0))
                return -EINVAL;

        client_id = disconn->u.in.client_id;
        if (client_id == 0 || client_id == U32_MAX)
                return -EINVAL;

        mutex_lock(&gdev->session_mutex);
        for (i = 0; i < ARRAY_SIZE(session->hgcm_client_ids); i++) {
                if (session->hgcm_client_ids[i] == client_id) {
                        session->hgcm_client_ids[i] = U32_MAX;
                        break;
                }
        }
        mutex_unlock(&gdev->session_mutex);

        if (i >= ARRAY_SIZE(session->hgcm_client_ids))
                return -EINVAL;

        ret = vbg_hgcm_disconnect(gdev, session->requestor, client_id,
                                  &disconn->hdr.rc);

        mutex_lock(&gdev->session_mutex);
        if (ret == 0 && disconn->hdr.rc >= 0)
                session->hgcm_client_ids[i] = 0;
        else
                session->hgcm_client_ids[i] = client_id;
        mutex_unlock(&gdev->session_mutex);

        return ret;
}

static bool vbg_param_valid(enum vmmdev_hgcm_function_parameter_type type)
{
        switch (type) {
        case VMMDEV_HGCM_PARM_TYPE_32BIT:
        case VMMDEV_HGCM_PARM_TYPE_64BIT:
        case VMMDEV_HGCM_PARM_TYPE_LINADDR:
        case VMMDEV_HGCM_PARM_TYPE_LINADDR_IN:
        case VMMDEV_HGCM_PARM_TYPE_LINADDR_OUT:
                return true;
        default:
                return false;
        }
}

static int vbg_ioctl_hgcm_call(struct vbg_dev *gdev,
                               struct vbg_session *session, bool f32bit,
                               struct vbg_ioctl_hgcm_call *call)
{
        size_t actual_size;
        u32 client_id;
        int i, ret;

        if (call->hdr.size_in < sizeof(*call))
                return -EINVAL;

        if (call->hdr.size_in != call->hdr.size_out)
                return -EINVAL;

        if (call->parm_count > VMMDEV_HGCM_MAX_PARMS)
                return -E2BIG;

        client_id = call->client_id;
        if (client_id == 0 || client_id == U32_MAX)
                return -EINVAL;

        actual_size = sizeof(*call);
        if (f32bit)
                actual_size += call->parm_count *
                               sizeof(struct vmmdev_hgcm_function_parameter32);
        else
                actual_size += call->parm_count *
                               sizeof(struct vmmdev_hgcm_function_parameter);
        if (call->hdr.size_in < actual_size) {
                vbg_debug("VBG_IOCTL_HGCM_CALL: hdr.size_in %d required size is %zd\n",
                          call->hdr.size_in, actual_size);
                return -EINVAL;
        }
        call->hdr.size_out = actual_size;

        /* Validate parameter types */
        if (f32bit) {
                struct vmmdev_hgcm_function_parameter32 *parm =
                        VBG_IOCTL_HGCM_CALL_PARMS32(call);

                for (i = 0; i < call->parm_count; i++)
                        if (!vbg_param_valid(parm[i].type))
                                return -EINVAL;
        } else {
                struct vmmdev_hgcm_function_parameter *parm =
                        VBG_IOCTL_HGCM_CALL_PARMS(call);

                for (i = 0; i < call->parm_count; i++)
                        if (!vbg_param_valid(parm[i].type))
                                return -EINVAL;
        }

        /*
         * Validate the client id.
         */
        mutex_lock(&gdev->session_mutex);
        for (i = 0; i < ARRAY_SIZE(session->hgcm_client_ids); i++)
                if (session->hgcm_client_ids[i] == client_id)
                        break;
        mutex_unlock(&gdev->session_mutex);
        if (i >= ARRAY_SIZE(session->hgcm_client_ids)) {
                vbg_debug("VBG_IOCTL_HGCM_CALL: INVALID handle. u32Client=%#08x\n",
                          client_id);
                return -EINVAL;
        }

        if (IS_ENABLED(CONFIG_COMPAT) && f32bit)
                ret = vbg_hgcm_call32(gdev, session->requestor, client_id,
                                      call->function, call->timeout_ms,
                                      VBG_IOCTL_HGCM_CALL_PARMS32(call),
                                      call->parm_count, &call->hdr.rc);
        else
                ret = vbg_hgcm_call(gdev, session->requestor, client_id,
                                    call->function, call->timeout_ms,
                                    VBG_IOCTL_HGCM_CALL_PARMS(call),
                                    call->parm_count, &call->hdr.rc);

        if (ret == -E2BIG) {
                /* E2BIG needs to be reported through the hdr.rc field. */
                call->hdr.rc = VERR_OUT_OF_RANGE;
                ret = 0;
        }

        if (ret && ret != -EINTR && ret != -ETIMEDOUT)
                vbg_err("VBG_IOCTL_HGCM_CALL error: %d\n", ret);

        return ret;
}

static int vbg_ioctl_log(struct vbg_ioctl_log *log)
{
        if (log->hdr.size_out != sizeof(log->hdr))
                return -EINVAL;

        vbg_info("%.*s", (int)(log->hdr.size_in - sizeof(log->hdr)),
                 log->u.in.msg);

        return 0;
}

static int vbg_ioctl_change_filter_mask(struct vbg_dev *gdev,
                                        struct vbg_session *session,
                                        struct vbg_ioctl_change_filter *filter)
{
        u32 or_mask, not_mask;

        if (vbg_ioctl_chk(&filter->hdr, sizeof(filter->u.in), 0))
                return -EINVAL;

        or_mask = filter->u.in.or_mask;
        not_mask = filter->u.in.not_mask;

        if ((or_mask | not_mask) & ~VMMDEV_EVENT_VALID_EVENT_MASK)
                return -EINVAL;

        return vbg_set_session_event_filter(gdev, session, or_mask, not_mask,
                                            false);
}

static int vbg_ioctl_acquire_guest_capabilities(struct vbg_dev *gdev,
             struct vbg_session *session,
             struct vbg_ioctl_acquire_guest_caps *caps)
{
        u32 flags, or_mask, not_mask;

        if (vbg_ioctl_chk(&caps->hdr, sizeof(caps->u.in), 0))
                return -EINVAL;

        flags = caps->u.in.flags;
        or_mask = caps->u.in.or_mask;
        not_mask = caps->u.in.not_mask;

        if (flags & ~VBGL_IOC_AGC_FLAGS_VALID_MASK)
                return -EINVAL;

        if ((or_mask | not_mask) & ~VMMDEV_GUEST_CAPABILITIES_MASK)
                return -EINVAL;

        return vbg_acquire_session_capabilities(gdev, session, or_mask,
                                                not_mask, flags, false);
}

static int vbg_ioctl_change_guest_capabilities(struct vbg_dev *gdev,
             struct vbg_session *session, struct vbg_ioctl_set_guest_caps *caps)
{
        u32 or_mask, not_mask;
        int ret;

        if (vbg_ioctl_chk(&caps->hdr, sizeof(caps->u.in), sizeof(caps->u.out)))
                return -EINVAL;

        or_mask = caps->u.in.or_mask;
        not_mask = caps->u.in.not_mask;

        if ((or_mask | not_mask) & ~VMMDEV_GUEST_CAPABILITIES_MASK)
                return -EINVAL;

        ret = vbg_set_session_capabilities(gdev, session, or_mask, not_mask,
                                           false);
        if (ret)
                return ret;

        caps->u.out.session_caps = session->set_guest_caps;
        caps->u.out.global_caps = gdev->guest_caps_host;

        return 0;
}

static int vbg_ioctl_check_balloon(struct vbg_dev *gdev,
                                   struct vbg_ioctl_check_balloon *balloon_info)
{
        if (vbg_ioctl_chk(&balloon_info->hdr, 0, sizeof(balloon_info->u.out)))
                return -EINVAL;

        balloon_info->u.out.balloon_chunks = gdev->mem_balloon.chunks;
        /*
         * Under Linux we handle VMMDEV_EVENT_BALLOON_CHANGE_REQUEST
         * events entirely in the kernel, see vbg_core_isr().
         */
        balloon_info->u.out.handle_in_r3 = false;

        return 0;
}

static int vbg_ioctl_write_core_dump(struct vbg_dev *gdev,
                                     struct vbg_session *session,
                                     struct vbg_ioctl_write_coredump *dump)
{
        struct vmmdev_write_core_dump *req;

        if (vbg_ioctl_chk(&dump->hdr, sizeof(dump->u.in), 0))
                return -EINVAL;

        req = vbg_req_alloc(sizeof(*req), VMMDEVREQ_WRITE_COREDUMP,
                            session->requestor);
        if (!req)
                return -ENOMEM;

        req->flags = dump->u.in.flags;
        dump->hdr.rc = vbg_req_perform(gdev, req);

        vbg_req_free(req, sizeof(*req));
        return 0;
}

/**
 * vbg_core_ioctl - Common IOCtl for user to kernel communication.
 * @session:    The client session.
 * @req:        The requested function.
 * @data:       The i/o data buffer, minimum size sizeof(struct vbg_ioctl_hdr).
 *
 * Return: %0 or negative errno value.
 */
int vbg_core_ioctl(struct vbg_session *session, unsigned int req, void *data)
{
        unsigned int req_no_size = req & ~IOCSIZE_MASK;
        struct vbg_dev *gdev = session->gdev;
        struct vbg_ioctl_hdr *hdr = data;
        bool f32bit = false;

        hdr->rc = VINF_SUCCESS;
        if (!hdr->size_out)
                hdr->size_out = hdr->size_in;

        /*
         * hdr->version and hdr->size_in / hdr->size_out minimum size are
         * already checked by vbg_misc_device_ioctl().
         */

        /* For VMMDEV_REQUEST hdr->type != VBG_IOCTL_HDR_TYPE_DEFAULT */
        if (req_no_size == VBG_IOCTL_VMMDEV_REQUEST(0) ||
            req == VBG_IOCTL_VMMDEV_REQUEST_BIG ||
            req == VBG_IOCTL_VMMDEV_REQUEST_BIG_ALT)
                return vbg_ioctl_vmmrequest(gdev, session, data);

        if (hdr->type != VBG_IOCTL_HDR_TYPE_DEFAULT)
                return -EINVAL;

        /* Fixed size requests. */
        switch (req) {
        case VBG_IOCTL_DRIVER_VERSION_INFO:
                return vbg_ioctl_driver_version_info(data);
        case VBG_IOCTL_HGCM_CONNECT:
                return vbg_ioctl_hgcm_connect(gdev, session, data);
        case VBG_IOCTL_HGCM_DISCONNECT:
                return vbg_ioctl_hgcm_disconnect(gdev, session, data);
        case VBG_IOCTL_WAIT_FOR_EVENTS:
                return vbg_ioctl_wait_for_events(gdev, session, data);
        case VBG_IOCTL_INTERRUPT_ALL_WAIT_FOR_EVENTS:
                return vbg_ioctl_interrupt_all_wait_events(gdev, session, data);
        case VBG_IOCTL_CHANGE_FILTER_MASK:
                return vbg_ioctl_change_filter_mask(gdev, session, data);
        case VBG_IOCTL_ACQUIRE_GUEST_CAPABILITIES:
                return vbg_ioctl_acquire_guest_capabilities(gdev, session, data);
        case VBG_IOCTL_CHANGE_GUEST_CAPABILITIES:
                return vbg_ioctl_change_guest_capabilities(gdev, session, data);
        case VBG_IOCTL_CHECK_BALLOON:
                return vbg_ioctl_check_balloon(gdev, data);
        case VBG_IOCTL_WRITE_CORE_DUMP:
                return vbg_ioctl_write_core_dump(gdev, session, data);
        }

        /* Variable sized requests. */
        switch (req_no_size) {
#ifdef CONFIG_COMPAT
        case VBG_IOCTL_HGCM_CALL_32(0):
                f32bit = true;
                fallthrough;
#endif
        case VBG_IOCTL_HGCM_CALL(0):
                return vbg_ioctl_hgcm_call(gdev, session, f32bit, data);
        case VBG_IOCTL_LOG(0):
        case VBG_IOCTL_LOG_ALT(0):
                return vbg_ioctl_log(data);
        }

        vbg_err_ratelimited("Userspace made an unknown ioctl req %#08x\n", req);
        return -ENOTTY;
}

/**
 * vbg_core_set_mouse_status - Report guest supported mouse-features to the host.
 *
 * @gdev:               The Guest extension device.
 * @features:           The set of features to report to the host.
 *
 * Return: %0 or negative errno value.
 */
int vbg_core_set_mouse_status(struct vbg_dev *gdev, u32 features)
{
        struct vmmdev_mouse_status *req;
        int rc;

        req = vbg_req_alloc(sizeof(*req), VMMDEVREQ_SET_MOUSE_STATUS,
                            VBG_KERNEL_REQUEST);
        if (!req)
                return -ENOMEM;

        req->mouse_features = features;
        req->pointer_pos_x = 0;
        req->pointer_pos_y = 0;

        rc = vbg_req_perform(gdev, req);
        if (rc < 0)
                vbg_err("%s error, rc: %d\n", __func__, rc);

        vbg_req_free(req, sizeof(*req));
        return vbg_status_code_to_errno(rc);
}

/* Core interrupt service routine. */
irqreturn_t vbg_core_isr(int irq, void *dev_id)
{
        struct vbg_dev *gdev = dev_id;
        struct vmmdev_events *req = gdev->ack_events_req;
        bool mouse_position_changed = false;
        unsigned long flags;
        u32 events = 0;
        int rc;

        if (!gdev->mmio->V.V1_04.have_events)
                return IRQ_NONE;

        /* Get and acknowlegde events. */
        req->header.rc = VERR_INTERNAL_ERROR;
        req->events = 0;
        rc = vbg_req_perform(gdev, req);
        if (rc < 0) {
                vbg_err("Error performing events req, rc: %d\n", rc);
                return IRQ_NONE;
        }

        events = req->events;

        if (events & VMMDEV_EVENT_MOUSE_POSITION_CHANGED) {
                mouse_position_changed = true;
                events &= ~VMMDEV_EVENT_MOUSE_POSITION_CHANGED;
        }

        if (events & VMMDEV_EVENT_HGCM) {
                wake_up(&gdev->hgcm_wq);
                events &= ~VMMDEV_EVENT_HGCM;
        }

        if (events & VMMDEV_EVENT_BALLOON_CHANGE_REQUEST) {
                schedule_work(&gdev->mem_balloon.work);
                events &= ~VMMDEV_EVENT_BALLOON_CHANGE_REQUEST;
        }

        if (events) {
                spin_lock_irqsave(&gdev->event_spinlock, flags);
                gdev->pending_events |= events;
                spin_unlock_irqrestore(&gdev->event_spinlock, flags);

                wake_up(&gdev->event_wq);
        }

        if (mouse_position_changed)
                vbg_linux_mouse_event(gdev);

        return IRQ_HANDLED;
}