// SPDX-License-Identifier: GPL-2.0 OR MIT
/*
 * Copyright 2016 VMware, Inc., Palo Alto, CA., USA
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sub license, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 * USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 */

#include <linux/frame.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/mem_encrypt.h>

#include <asm/hypervisor.h>

#include "vmwgfx_drv.h"
#include "vmwgfx_msg.h"

#define MESSAGE_STATUS_SUCCESS  0x0001
#define MESSAGE_STATUS_DORECV   0x0002
#define MESSAGE_STATUS_CPT      0x0010
#define MESSAGE_STATUS_HB       0x0080

#define RPCI_PROTOCOL_NUM       0x49435052
#define GUESTMSG_FLAG_COOKIE    0x80000000

#define RETRIES                 3

#define VMW_HYPERVISOR_MAGIC    0x564D5868

#define VMW_PORT_CMD_MSG        30
#define VMW_PORT_CMD_HB_MSG     0
#define VMW_PORT_CMD_OPEN_CHANNEL  (MSG_TYPE_OPEN << 16 | VMW_PORT_CMD_MSG)
#define VMW_PORT_CMD_CLOSE_CHANNEL (MSG_TYPE_CLOSE << 16 | VMW_PORT_CMD_MSG)
#define VMW_PORT_CMD_SENDSIZE   (MSG_TYPE_SENDSIZE << 16 | VMW_PORT_CMD_MSG)
#define VMW_PORT_CMD_RECVSIZE   (MSG_TYPE_RECVSIZE << 16 | VMW_PORT_CMD_MSG)
#define VMW_PORT_CMD_RECVSTATUS (MSG_TYPE_RECVSTATUS << 16 | VMW_PORT_CMD_MSG)

#define HIGH_WORD(X) ((X & 0xFFFF0000) >> 16)

#define MAX_USER_MSG_LENGTH     PAGE_SIZE

static u32 vmw_msg_enabled = 1;

enum rpc_msg_type {
        MSG_TYPE_OPEN,
        MSG_TYPE_SENDSIZE,
        MSG_TYPE_SENDPAYLOAD,
        MSG_TYPE_RECVSIZE,
        MSG_TYPE_RECVPAYLOAD,
        MSG_TYPE_RECVSTATUS,
        MSG_TYPE_CLOSE,
};

struct rpc_channel {
        u16 channel_id;
        u32 cookie_high;
        u32 cookie_low;
};



/**
 * vmw_open_channel
 *
 * @channel: RPC channel
 * @protocol:
 *
 * Returns: 0 on success
 */
static int vmw_open_channel(struct rpc_channel *channel, unsigned int protocol)
{
        unsigned long eax, ebx, ecx, edx, si = 0, di = 0;

        VMW_PORT(VMW_PORT_CMD_OPEN_CHANNEL,
                (protocol | GUESTMSG_FLAG_COOKIE), si, di,
                0,
                VMW_HYPERVISOR_MAGIC,
                eax, ebx, ecx, edx, si, di);

        if ((HIGH_WORD(ecx) & MESSAGE_STATUS_SUCCESS) == 0)
                return -EINVAL;

        channel->channel_id  = HIGH_WORD(edx);
        channel->cookie_high = si;
        channel->cookie_low  = di;

        return 0;
}



/**
 * vmw_close_channel
 *
 * @channel: RPC channel
 *
 * Returns: 0 on success
 */
static int vmw_close_channel(struct rpc_channel *channel)
{
        unsigned long eax, ebx, ecx, edx, si, di;

        /* Set up additional parameters */
        si  = channel->cookie_high;
        di  = channel->cookie_low;

        VMW_PORT(VMW_PORT_CMD_CLOSE_CHANNEL,
                0, si, di,
                channel->channel_id << 16,
                VMW_HYPERVISOR_MAGIC,
                eax, ebx, ecx, edx, si, di);

        if ((HIGH_WORD(ecx) & MESSAGE_STATUS_SUCCESS) == 0)
                return -EINVAL;

        return 0;
}

/**
 * vmw_port_hb_out - Send the message payload either through the
 * high-bandwidth port if available, or through the backdoor otherwise.
 * @channel: The rpc channel.
 * @msg: NULL-terminated message.
 * @hb: Whether the high-bandwidth port is available.
 *
 * Return: The port status.
 */
static unsigned long vmw_port_hb_out(struct rpc_channel *channel,
                                     const char *msg, bool hb)
{
        unsigned long si, di, eax, ebx, ecx, edx;
        unsigned long msg_len = strlen(msg);

        /* HB port can't access encrypted memory. */
        if (hb && !mem_encrypt_active()) {
                unsigned long bp = channel->cookie_high;

                si = (uintptr_t) msg;
                di = channel->cookie_low;

                VMW_PORT_HB_OUT(
                        (MESSAGE_STATUS_SUCCESS << 16) | VMW_PORT_CMD_HB_MSG,
                        msg_len, si, di,
                        VMWARE_HYPERVISOR_HB | (channel->channel_id << 16) |
                        VMWARE_HYPERVISOR_OUT,
                        VMW_HYPERVISOR_MAGIC, bp,
                        eax, ebx, ecx, edx, si, di);

                return ebx;
        }

        /* HB port not available. Send the message 4 bytes at a time. */
        ecx = MESSAGE_STATUS_SUCCESS << 16;
        while (msg_len && (HIGH_WORD(ecx) & MESSAGE_STATUS_SUCCESS)) {
                unsigned int bytes = min_t(size_t, msg_len, 4);
                unsigned long word = 0;

                memcpy(&word, msg, bytes);
                msg_len -= bytes;
                msg += bytes;
                si = channel->cookie_high;
                di = channel->cookie_low;

                VMW_PORT(VMW_PORT_CMD_MSG | (MSG_TYPE_SENDPAYLOAD << 16),
                         word, si, di,
                         channel->channel_id << 16,
                         VMW_HYPERVISOR_MAGIC,
                         eax, ebx, ecx, edx, si, di);
        }

        return ecx;
}

/**
 * vmw_port_hb_in - Receive the message payload either through the
 * high-bandwidth port if available, or through the backdoor otherwise.
 * @channel: The rpc channel.
 * @reply: Pointer to buffer holding reply.
 * @reply_len: Length of the reply.
 * @hb: Whether the high-bandwidth port is available.
 *
 * Return: The port status.
 */
static unsigned long vmw_port_hb_in(struct rpc_channel *channel, char *reply,
                                    unsigned long reply_len, bool hb)
{
        unsigned long si, di, eax, ebx, ecx, edx;

        /* HB port can't access encrypted memory */
        if (hb && !mem_encrypt_active()) {
                unsigned long bp = channel->cookie_low;

                si = channel->cookie_high;
                di = (uintptr_t) reply;

                VMW_PORT_HB_IN(
                        (MESSAGE_STATUS_SUCCESS << 16) | VMW_PORT_CMD_HB_MSG,
                        reply_len, si, di,
                        VMWARE_HYPERVISOR_HB | (channel->channel_id << 16),
                        VMW_HYPERVISOR_MAGIC, bp,
                        eax, ebx, ecx, edx, si, di);

                return ebx;
        }

        /* HB port not available. Retrieve the message 4 bytes at a time. */
        ecx = MESSAGE_STATUS_SUCCESS << 16;
        while (reply_len) {
                unsigned int bytes = min_t(unsigned long, reply_len, 4);

                si = channel->cookie_high;
                di = channel->cookie_low;

                VMW_PORT(VMW_PORT_CMD_MSG | (MSG_TYPE_RECVPAYLOAD << 16),
                         MESSAGE_STATUS_SUCCESS, si, di,
                         channel->channel_id << 16,
                         VMW_HYPERVISOR_MAGIC,
                         eax, ebx, ecx, edx, si, di);

                if ((HIGH_WORD(ecx) & MESSAGE_STATUS_SUCCESS) == 0)
                        break;

                memcpy(reply, &ebx, bytes);
                reply_len -= bytes;
                reply += bytes;
        }

        return ecx;
}


/**
 * vmw_send_msg: Sends a message to the host
 *
 * @channel: RPC channel
 * @logmsg: NULL terminated string
 *
 * Returns: 0 on success
 */
static int vmw_send_msg(struct rpc_channel *channel, const char *msg)
{
        unsigned long eax, ebx, ecx, edx, si, di;
        size_t msg_len = strlen(msg);
        int retries = 0;

        while (retries < RETRIES) {
                retries++;

                /* Set up additional parameters */
                si  = channel->cookie_high;
                di  = channel->cookie_low;

                VMW_PORT(VMW_PORT_CMD_SENDSIZE,
                        msg_len, si, di,
                        channel->channel_id << 16,
                        VMW_HYPERVISOR_MAGIC,
                        eax, ebx, ecx, edx, si, di);

                if ((HIGH_WORD(ecx) & MESSAGE_STATUS_SUCCESS) == 0) {
                        /* Expected success. Give up. */
                        return -EINVAL;
                }

                /* Send msg */
                ebx = vmw_port_hb_out(channel, msg,
                                      !!(HIGH_WORD(ecx) & MESSAGE_STATUS_HB));

                if ((HIGH_WORD(ebx) & MESSAGE_STATUS_SUCCESS) != 0) {
                        return 0;
                } else if ((HIGH_WORD(ebx) & MESSAGE_STATUS_CPT) != 0) {
                        /* A checkpoint occurred. Retry. */
                        continue;
                } else {
                        break;
                }
        }

        return -EINVAL;
}
STACK_FRAME_NON_STANDARD(vmw_send_msg);


/**
 * vmw_recv_msg: Receives a message from the host
 *
 * Note:  It is the caller's responsibility to call kfree() on msg.
 *
 * @channel:  channel opened by vmw_open_channel
 * @msg:  [OUT] message received from the host
 * @msg_len: message length
 */
static int vmw_recv_msg(struct rpc_channel *channel, void **msg,
                        size_t *msg_len)
{
        unsigned long eax, ebx, ecx, edx, si, di;
        char *reply;
        size_t reply_len;
        int retries = 0;


        *msg_len = 0;
        *msg = NULL;

        while (retries < RETRIES) {
                retries++;

                /* Set up additional parameters */
                si  = channel->cookie_high;
                di  = channel->cookie_low;

                VMW_PORT(VMW_PORT_CMD_RECVSIZE,
                        0, si, di,
                        channel->channel_id << 16,
                        VMW_HYPERVISOR_MAGIC,
                        eax, ebx, ecx, edx, si, di);

                if ((HIGH_WORD(ecx) & MESSAGE_STATUS_SUCCESS) == 0) {
                        DRM_ERROR("Failed to get reply size for host message.\n");
                        return -EINVAL;
                }

                /* No reply available.  This is okay. */
                if ((HIGH_WORD(ecx) & MESSAGE_STATUS_DORECV) == 0)
                        return 0;

                reply_len = ebx;
                reply     = kzalloc(reply_len + 1, GFP_KERNEL);
                if (!reply) {
                        DRM_ERROR("Cannot allocate memory for host message reply.\n");
                        return -ENOMEM;
                }


                /* Receive buffer */
                ebx = vmw_port_hb_in(channel, reply, reply_len,
                                     !!(HIGH_WORD(ecx) & MESSAGE_STATUS_HB));
                if ((HIGH_WORD(ebx) & MESSAGE_STATUS_SUCCESS) == 0) {
                        kfree(reply);
                        reply = NULL;
                        if ((HIGH_WORD(ebx) & MESSAGE_STATUS_CPT) != 0) {
                                /* A checkpoint occurred. Retry. */
                                continue;
                        }

                        return -EINVAL;
                }

                reply[reply_len] = '\0';


                /* Ack buffer */
                si  = channel->cookie_high;
                di  = channel->cookie_low;

                VMW_PORT(VMW_PORT_CMD_RECVSTATUS,
                        MESSAGE_STATUS_SUCCESS, si, di,
                        channel->channel_id << 16,
                        VMW_HYPERVISOR_MAGIC,
                        eax, ebx, ecx, edx, si, di);

                if ((HIGH_WORD(ecx) & MESSAGE_STATUS_SUCCESS) == 0) {
                        kfree(reply);
                        reply = NULL;
                        if ((HIGH_WORD(ecx) & MESSAGE_STATUS_CPT) != 0) {
                                /* A checkpoint occurred. Retry. */
                                continue;
                        }

                        return -EINVAL;
                }

                break;
        }

        if (!reply)
                return -EINVAL;

        *msg_len = reply_len;
        *msg     = reply;

        return 0;
}
STACK_FRAME_NON_STANDARD(vmw_recv_msg);


/**
 * vmw_host_get_guestinfo: Gets a GuestInfo parameter
 *
 * Gets the value of a  GuestInfo.* parameter.  The value returned will be in
 * a string, and it is up to the caller to post-process.
 *
 * @guest_info_param:  Parameter to get, e.g. GuestInfo.svga.gl3
 * @buffer: if NULL, *reply_len will contain reply size.
 * @length: size of the reply_buf.  Set to size of reply upon return
 *
 * Returns: 0 on success
 */
int vmw_host_get_guestinfo(const char *guest_info_param,
                           char *buffer, size_t *length)
{
        struct rpc_channel channel;
        char *msg, *reply = NULL;
        size_t reply_len = 0;

        if (!vmw_msg_enabled)
                return -ENODEV;

        if (!guest_info_param || !length)
                return -EINVAL;

        msg = kasprintf(GFP_KERNEL, "info-get %s", guest_info_param);
        if (!msg) {
                DRM_ERROR("Cannot allocate memory to get guest info \"%s\".",
                          guest_info_param);
                return -ENOMEM;
        }

        if (vmw_open_channel(&channel, RPCI_PROTOCOL_NUM))
                goto out_open;

        if (vmw_send_msg(&channel, msg) ||
            vmw_recv_msg(&channel, (void *) &reply, &reply_len))
                goto out_msg;

        vmw_close_channel(&channel);
        if (buffer && reply && reply_len > 0) {
                /* Remove reply code, which are the first 2 characters of
                 * the reply
                 */
                reply_len = max(reply_len - 2, (size_t) 0);
                reply_len = min(reply_len, *length);

                if (reply_len > 0)
                        memcpy(buffer, reply + 2, reply_len);
        }

        *length = reply_len;

        kfree(reply);
        kfree(msg);

        return 0;

out_msg:
        vmw_close_channel(&channel);
        kfree(reply);
out_open:
        *length = 0;
        kfree(msg);
        DRM_ERROR("Failed to get guest info \"%s\".", guest_info_param);

        return -EINVAL;
}



/**
 * vmw_host_log: Sends a log message to the host
 *
 * @log: NULL terminated string
 *
 * Returns: 0 on success
 */
int vmw_host_log(const char *log)
{
        struct rpc_channel channel;
        char *msg;
        int ret = 0;


        if (!vmw_msg_enabled)
                return -ENODEV;

        if (!log)
                return ret;

        msg = kasprintf(GFP_KERNEL, "log %s", log);
        if (!msg) {
                DRM_ERROR("Cannot allocate memory for host log message.\n");
                return -ENOMEM;
        }

        if (vmw_open_channel(&channel, RPCI_PROTOCOL_NUM))
                goto out_open;

        if (vmw_send_msg(&channel, msg))
                goto out_msg;

        vmw_close_channel(&channel);
        kfree(msg);

        return 0;

out_msg:
        vmw_close_channel(&channel);
out_open:
        kfree(msg);
        DRM_ERROR("Failed to send host log message.\n");

        return -EINVAL;
}


/**
 * vmw_msg_ioctl: Sends and receveives a message to/from host from/to user-space
 *
 * Sends a message from user-space to host.
 * Can also receive a result from host and return that to user-space.
 *
 * @dev: Identifies the drm device.
 * @data: Pointer to the ioctl argument.
 * @file_priv: Identifies the caller.
 * Return: Zero on success, negative error code on error.
 */

int vmw_msg_ioctl(struct drm_device *dev, void *data,
                  struct drm_file *file_priv)
{
        struct drm_vmw_msg_arg *arg =
                (struct drm_vmw_msg_arg *) data;
        struct rpc_channel channel;
        char *msg;
        int length;

        msg = kmalloc(MAX_USER_MSG_LENGTH, GFP_KERNEL);
        if (!msg) {
                DRM_ERROR("Cannot allocate memory for log message.\n");
                return -ENOMEM;
        }

        length = strncpy_from_user(msg, (void __user *)((unsigned long)arg->send),
                                   MAX_USER_MSG_LENGTH);
        if (length < 0 || length >= MAX_USER_MSG_LENGTH) {
                DRM_ERROR("Userspace message access failure.\n");
                kfree(msg);
                return -EINVAL;
        }


        if (vmw_open_channel(&channel, RPCI_PROTOCOL_NUM)) {
                DRM_ERROR("Failed to open channel.\n");
                goto out_open;
        }

        if (vmw_send_msg(&channel, msg)) {
                DRM_ERROR("Failed to send message to host.\n");
                goto out_msg;
        }

        if (!arg->send_only) {
                char *reply = NULL;
                size_t reply_len = 0;

                if (vmw_recv_msg(&channel, (void *) &reply, &reply_len)) {
                        DRM_ERROR("Failed to receive message from host.\n");
                        goto out_msg;
                }
                if (reply && reply_len > 0) {
                        if (copy_to_user((void __user *)((unsigned long)arg->receive),
                                                         reply, reply_len)) {
                                DRM_ERROR("Failed to copy message to userspace.\n");
                                kfree(reply);
                                goto out_msg;
                        }
                        arg->receive_len = (__u32)reply_len;
                }
                kfree(reply);
        }

        vmw_close_channel(&channel);
        kfree(msg);

        return 0;

out_msg:
        vmw_close_channel(&channel);
out_open:
        kfree(msg);

        return -EINVAL;
}