// SPDX-License-Identifier: GPL-2.0-only
/*
 *
 * Copyright (c) 2009, Microsoft Corporation.
 *
 * Authors:
 *   Haiyang Zhang <haiyangz@microsoft.com>
 *   Hank Janssen  <hjanssen@microsoft.com>
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/delay.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/hyperv.h>
#include <linux/export.h>
#include <linux/io.h>
#include <linux/set_memory.h>
#include <asm/mshyperv.h>

#include "hyperv_vmbus.h"


struct vmbus_connection vmbus_connection = {
        .conn_state             = DISCONNECTED,
        .unload_event           = COMPLETION_INITIALIZER(
                                  vmbus_connection.unload_event),
        .next_gpadl_handle      = ATOMIC_INIT(0xE1E10),

        .ready_for_suspend_event = COMPLETION_INITIALIZER(
                                  vmbus_connection.ready_for_suspend_event),
        .all_offers_delivered_event = COMPLETION_INITIALIZER(
                                  vmbus_connection.all_offers_delivered_event),
};
EXPORT_SYMBOL_GPL(vmbus_connection);

/*
 * Negotiated protocol version with the host.
 */
__u32 vmbus_proto_version;
EXPORT_SYMBOL_GPL(vmbus_proto_version);

/*
 * Table of VMBus versions listed from newest to oldest.
 * VERSION_WIN7 and VERSION_WS2008 are no longer supported in
 * Linux guests and are not listed.
 */
static __u32 vmbus_versions[] = {
        VERSION_WIN10_V6_0,
        VERSION_WIN10_V5_3,
        VERSION_WIN10_V5_2,
        VERSION_WIN10_V5_1,
        VERSION_WIN10_V5,
        VERSION_WIN10_V4_1,
        VERSION_WIN10,
        VERSION_WIN8_1,
        VERSION_WIN8
};

/*
 * Maximal VMBus protocol version guests can negotiate.  Useful to cap the
 * VMBus version for testing and debugging purpose.
 */
static uint max_version = VERSION_WIN10_V6_0;

module_param(max_version, uint, S_IRUGO);
MODULE_PARM_DESC(max_version,
                 "Maximal VMBus protocol version which can be negotiated");

int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
{
        int ret = 0;
        struct vmbus_channel_initiate_contact *msg;
        unsigned long flags;

        init_completion(&msginfo->waitevent);

        msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;

        memset(msg, 0, sizeof(*msg));
        msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
        msg->vmbus_version_requested = version;

        /*
         * VMBus protocol 5.0 (VERSION_WIN10_V5) and higher require that we must
         * use VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate Contact Message,
         * and for subsequent messages, we must use the Message Connection ID
         * field in the host-returned Version Response Message. And, with
         * VERSION_WIN10_V5 and higher, we don't use msg->interrupt_page, but we
         * tell the host explicitly that we still use VMBUS_MESSAGE_SINT(2) for
         * compatibility.
         *
         * On old hosts, we should always use VMBUS_MESSAGE_CONNECTION_ID (1).
         */
        if (version >= VERSION_WIN10_V5) {
                msg->msg_sint = VMBUS_MESSAGE_SINT;
                msg->msg_vtl = ms_hyperv.vtl;
                vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID_4;
        } else {
                msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
                vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
        }

        if (vmbus_is_confidential() && version >= VERSION_WIN10_V6_0)
                msg->feature_flags = VMBUS_FEATURE_FLAG_CONFIDENTIAL_CHANNELS;

        /*
         * shared_gpa_boundary is zero in non-SNP VMs, so it's safe to always
         * bitwise OR it
         */
        msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]) |
                                ms_hyperv.shared_gpa_boundary;
        msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]) |
                                ms_hyperv.shared_gpa_boundary;

        msg->target_vcpu = hv_cpu_number_to_vp_number(VMBUS_CONNECT_CPU);

        /*
         * Add to list before we send the request since we may
         * receive the response before returning from this routine
         */
        spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
        list_add_tail(&msginfo->msglistentry,
                      &vmbus_connection.chn_msg_list);

        spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);

        ret = vmbus_post_msg(msg,
                             sizeof(struct vmbus_channel_initiate_contact),
                             true);

        trace_vmbus_negotiate_version(msg, ret);

        if (ret != 0) {
                spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
                list_del(&msginfo->msglistentry);
                spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
                                        flags);
                return ret;
        }

        /* Wait for the connection response */
        wait_for_completion(&msginfo->waitevent);

        spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
        list_del(&msginfo->msglistentry);
        spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);

        /* Check if successful */
        if (msginfo->response.version_response.version_supported) {
                vmbus_connection.conn_state = CONNECTED;

                if (version >= VERSION_WIN10_V5)
                        vmbus_connection.msg_conn_id =
                                msginfo->response.version_response.msg_conn_id;
        } else {
                return -ECONNREFUSED;
        }

        return ret;
}

/*
 * vmbus_connect - Sends a connect request on the partition service connection
 */
int vmbus_connect(void)
{
        struct vmbus_channel_msginfo *msginfo = NULL;
        int i, ret = 0;
        __u32 version;

        /* Initialize the vmbus connection */
        vmbus_connection.conn_state = CONNECTING;
        vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
        if (!vmbus_connection.work_queue) {
                ret = -ENOMEM;
                goto cleanup;
        }

        vmbus_connection.rescind_work_queue =
                create_workqueue("hv_vmbus_rescind");
        if (!vmbus_connection.rescind_work_queue) {
                ret = -ENOMEM;
                goto cleanup;
        }
        vmbus_connection.ignore_any_offer_msg = false;

        vmbus_connection.handle_primary_chan_wq =
                create_workqueue("hv_pri_chan");
        if (!vmbus_connection.handle_primary_chan_wq) {
                ret = -ENOMEM;
                goto cleanup;
        }

        vmbus_connection.handle_sub_chan_wq =
                create_workqueue("hv_sub_chan");
        if (!vmbus_connection.handle_sub_chan_wq) {
                ret = -ENOMEM;
                goto cleanup;
        }

        INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
        spin_lock_init(&vmbus_connection.channelmsg_lock);

        INIT_LIST_HEAD(&vmbus_connection.chn_list);
        mutex_init(&vmbus_connection.channel_mutex);

        /*
         * The following Hyper-V interrupt and monitor pages can be used by
         * UIO for mapping to user-space, so they should always be allocated on
         * system page boundaries. The system page size must be >= the Hyper-V
         * page size.
         */
        BUILD_BUG_ON(PAGE_SIZE < HV_HYP_PAGE_SIZE);

        /*
         * Setup the vmbus event connection for channel interrupt
         * abstraction stuff
         */
        vmbus_connection.int_page =
                (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
        if (vmbus_connection.int_page == NULL) {
                ret = -ENOMEM;
                goto cleanup;
        }

        vmbus_connection.recv_int_page = vmbus_connection.int_page;
        vmbus_connection.send_int_page =
                (void *)((unsigned long)vmbus_connection.int_page +
                        (HV_HYP_PAGE_SIZE >> 1));

        /*
         * Setup the monitor notification facility. The 1st page for
         * parent->child and the 2nd page for child->parent
         */
        vmbus_connection.monitor_pages[0] = (void *)__get_free_page(GFP_KERNEL);
        vmbus_connection.monitor_pages[1] = (void *)__get_free_page(GFP_KERNEL);
        if ((vmbus_connection.monitor_pages[0] == NULL) ||
            (vmbus_connection.monitor_pages[1] == NULL)) {
                ret = -ENOMEM;
                goto cleanup;
        }

        ret = set_memory_decrypted((unsigned long)
                                vmbus_connection.monitor_pages[0], 1);
        ret |= set_memory_decrypted((unsigned long)
                                vmbus_connection.monitor_pages[1], 1);
        if (ret) {
                /*
                 * If set_memory_decrypted() fails, the encryption state
                 * of the memory is unknown. So leak the memory instead
                 * of risking returning decrypted memory to the free list.
                 * For simplicity, always handle both pages the same.
                 */
                vmbus_connection.monitor_pages[0] = NULL;
                vmbus_connection.monitor_pages[1] = NULL;
                goto cleanup;
        }

        /*
         * Set_memory_decrypted() will change the memory contents if
         * decryption occurs, so zero monitor pages here.
         */
        memset(vmbus_connection.monitor_pages[0], 0x00, HV_HYP_PAGE_SIZE);
        memset(vmbus_connection.monitor_pages[1], 0x00, HV_HYP_PAGE_SIZE);

        msginfo = kzalloc(sizeof(*msginfo) +
                          sizeof(struct vmbus_channel_initiate_contact),
                          GFP_KERNEL);
        if (msginfo == NULL) {
                ret = -ENOMEM;
                goto cleanup;
        }

        /*
         * Negotiate a compatible VMBUS version number with the
         * host. We start with the highest number we can support
         * and work our way down until we negotiate a compatible
         * version.
         */

        for (i = 0; ; i++) {
                if (i == ARRAY_SIZE(vmbus_versions)) {
                        ret = -EDOM;
                        goto cleanup;
                }

                version = vmbus_versions[i];
                if (version > max_version)
                        continue;

                ret = vmbus_negotiate_version(msginfo, version);
                if (ret == -ETIMEDOUT)
                        goto cleanup;

                if (vmbus_connection.conn_state == CONNECTED)
                        break;
        }

        if (hv_is_isolation_supported() && version < VERSION_WIN10_V5_2) {
                pr_err("Invalid VMBus version %d.%d (expected >= %d.%d) from the host supporting isolation\n",
                       version >> 16, version & 0xFFFF, VERSION_WIN10_V5_2 >> 16, VERSION_WIN10_V5_2 & 0xFFFF);
                ret = -EINVAL;
                goto cleanup;
        }

        vmbus_proto_version = version;
        pr_info("Vmbus version:%d.%d\n",
                version >> 16, version & 0xFFFF);

        vmbus_connection.channels = kzalloc_objs(struct vmbus_channel *,
                                                 MAX_CHANNEL_RELIDS);
        if (vmbus_connection.channels == NULL) {
                ret = -ENOMEM;
                goto cleanup;
        }

        kfree(msginfo);
        return 0;

cleanup:
        pr_err("Unable to connect to host\n");

        vmbus_connection.conn_state = DISCONNECTED;
        vmbus_disconnect();

        kfree(msginfo);

        return ret;
}

void vmbus_disconnect(void)
{
        /*
         * First send the unload request to the host.
         */
        vmbus_initiate_unload(false);

        if (vmbus_connection.handle_sub_chan_wq)
                destroy_workqueue(vmbus_connection.handle_sub_chan_wq);

        if (vmbus_connection.handle_primary_chan_wq)
                destroy_workqueue(vmbus_connection.handle_primary_chan_wq);

        if (vmbus_connection.rescind_work_queue)
                destroy_workqueue(vmbus_connection.rescind_work_queue);

        if (vmbus_connection.work_queue)
                destroy_workqueue(vmbus_connection.work_queue);

        if (vmbus_connection.int_page) {
                free_page((unsigned long)vmbus_connection.int_page);
                vmbus_connection.int_page = NULL;
        }

        if (vmbus_connection.monitor_pages[0]) {
                if (!set_memory_encrypted(
                        (unsigned long)vmbus_connection.monitor_pages[0], 1))
                        free_page((unsigned long)
                                vmbus_connection.monitor_pages[0]);
                vmbus_connection.monitor_pages[0] = NULL;
        }

        if (vmbus_connection.monitor_pages[1]) {
                if (!set_memory_encrypted(
                        (unsigned long)vmbus_connection.monitor_pages[1], 1))
                        free_page((unsigned long)
                                vmbus_connection.monitor_pages[1]);
                vmbus_connection.monitor_pages[1] = NULL;
        }
}

/*
 * relid2channel - Get the channel object given its
 * child relative id (ie channel id)
 */
struct vmbus_channel *relid2channel(u32 relid)
{
        if (vmbus_connection.channels == NULL) {
                pr_warn_once("relid2channel: relid=%d: No channels mapped!\n", relid);
                return NULL;
        }
        if (WARN_ON(relid >= MAX_CHANNEL_RELIDS))
                return NULL;
        return READ_ONCE(vmbus_connection.channels[relid]);
}

/*
 * vmbus_on_event - Process a channel event notification
 *
 * For batched channels (default) optimize host to guest signaling
 * by ensuring:
 * 1. While reading the channel, we disable interrupts from host.
 * 2. Ensure that we process all posted messages from the host
 *    before returning from this callback.
 * 3. Once we return, enable signaling from the host. Once this
 *    state is set we check to see if additional packets are
 *    available to read. In this case we repeat the process.
 *    If this tasklet has been running for a long time
 *    then reschedule ourselves.
 */
void vmbus_on_event(unsigned long data)
{
        struct vmbus_channel *channel = (void *) data;
        void (*callback_fn)(void *context);

        trace_vmbus_on_event(channel);

        hv_debug_delay_test(channel, INTERRUPT_DELAY);

        /* A channel once created is persistent even when
         * there is no driver handling the device. An
         * unloading driver sets the onchannel_callback to NULL.
         */
        callback_fn = READ_ONCE(channel->onchannel_callback);
        if (unlikely(!callback_fn))
                return;

        (*callback_fn)(channel->channel_callback_context);

        if (channel->callback_mode != HV_CALL_BATCHED)
                return;

        if (likely(hv_end_read(&channel->inbound) == 0))
                return;

        hv_begin_read(&channel->inbound);
        tasklet_schedule(&channel->callback_event);
}

/*
 * vmbus_post_msg - Send a msg on the vmbus's message connection
 */
int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
{
        struct vmbus_channel_message_header *hdr;
        union hv_connection_id conn_id;
        int ret = 0;
        int retries = 0;
        u32 usec = 1;

        conn_id.asu32 = 0;
        conn_id.u.id = vmbus_connection.msg_conn_id;

        /*
         * hv_post_message() can have transient failures because of
         * insufficient resources. Retry the operation a couple of
         * times before giving up.
         */
        while (retries < 100) {
                ret = hv_post_message(conn_id, 1, buffer, buflen);

                switch (ret) {
                case HV_STATUS_INVALID_CONNECTION_ID:
                        /*
                         * See vmbus_negotiate_version(): VMBus protocol 5.0
                         * and higher require that we must use
                         * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate
                         * Contact message, but on old hosts that only
                         * support VMBus protocol 4.0 or lower, here we get
                         * HV_STATUS_INVALID_CONNECTION_ID and we should
                         * return an error immediately without retrying.
                         */
                        hdr = buffer;
                        if (hdr->msgtype == CHANNELMSG_INITIATE_CONTACT)
                                return -EINVAL;
                        /*
                         * We could get this if we send messages too
                         * frequently.
                         */
                        ret = -EAGAIN;
                        break;
                case HV_STATUS_INSUFFICIENT_MEMORY:
                case HV_STATUS_INSUFFICIENT_BUFFERS:
                        ret = -ENOBUFS;
                        break;
                case HV_STATUS_SUCCESS:
                        return ret;
                default:
                        pr_err("hv_post_msg() failed; error code:%d\n", ret);
                        return -EINVAL;
                }

                retries++;
                if (can_sleep && usec > 1000)
                        msleep(usec / 1000);
                else if (usec < MAX_UDELAY_MS * 1000)
                        udelay(usec);
                else
                        mdelay(usec / 1000);

                if (retries < 22)
                        usec *= 2;
        }
        return ret;
}

/*
 * vmbus_set_event - Send an event notification to the parent
 */
void vmbus_set_event(struct vmbus_channel *channel)
{
        u32 child_relid = channel->offermsg.child_relid;

        if (!channel->is_dedicated_interrupt)
                vmbus_send_interrupt(child_relid);

        ++channel->sig_events;

        if (ms_hyperv.paravisor_present) {
                if (hv_isolation_type_snp())
                        hv_ghcb_hypercall(HVCALL_SIGNAL_EVENT, &channel->sig_event,
                                          NULL, sizeof(channel->sig_event));
                else if (hv_isolation_type_tdx())
                        hv_tdx_hypercall(HVCALL_SIGNAL_EVENT | HV_HYPERCALL_FAST_BIT,
                                         channel->sig_event, 0);
                else
                        WARN_ON_ONCE(1);
        } else {
                u64 control = HVCALL_SIGNAL_EVENT;

                control |= hv_nested ? HV_HYPERCALL_NESTED : 0;
                hv_do_fast_hypercall8(control, channel->sig_event);
        }
}
EXPORT_SYMBOL_GPL(vmbus_set_event);