/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2011 NetApp, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY NETAPP, INC ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL NETAPP, INC OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/linker_set.h>
#include <sys/_iovec.h>
#include <sys/mman.h>

#include <x86/psl.h>

#include <machine/vmm.h>
#include <machine/vmm_instruction_emul.h>
#include <vmmapi.h>

#include <stdio.h>
#include <string.h>
#include <assert.h>

#include "bhyverun.h"
#include "config.h"
#include "inout.h"

SET_DECLARE(inout_port_set, struct inout_port);

#define MAX_IOPORTS     (1 << 16)

#define VERIFY_IOPORT(port, size) \
        assert((port) >= 0 && (size) > 0 && ((port) + (size)) <= MAX_IOPORTS)

static struct {
        const char      *name;
        int             flags;
        inout_func_t    handler;
        void            *arg;
} inout_handlers[MAX_IOPORTS];

static int
default_inout(struct vmctx *ctx __unused, int in,
    int port __unused, int bytes, uint32_t *eax, void *arg __unused)
{
        if (in) {
                switch (bytes) {
                case 4:
                        *eax = 0xffffffff;
                        break;
                case 2:
                        *eax = 0xffff;
                        break;
                case 1:
                        *eax = 0xff;
                        break;
                }
        }

        return (0);
}

static void
register_default_iohandler(int start, int size)
{
        struct inout_port iop;

        VERIFY_IOPORT(start, size);

        bzero(&iop, sizeof(iop));
        iop.name = "default";
        iop.port = start;
        iop.size = size;
        iop.flags = IOPORT_F_INOUT | IOPORT_F_DEFAULT;
        iop.handler = default_inout;

        register_inout(&iop);
}

int
emulate_inout(struct vmctx *ctx, struct vcpu *vcpu, struct vm_exit *vmexit)
{
        int addrsize, bytes, flags, in, port, prot, rep;
        uint32_t eax, val;
        inout_func_t handler;
        void *arg;
        int error, fault, retval;
        enum vm_reg_name idxreg;
        uint64_t gla, index, iterations, count;
        struct vm_inout_str *vis;
        struct iovec iov[2];

        bytes = vmexit->u.inout.bytes;
        in = vmexit->u.inout.in;
        port = vmexit->u.inout.port;

        assert(port < MAX_IOPORTS);
        assert(bytes == 1 || bytes == 2 || bytes == 4);

        handler = inout_handlers[port].handler;

        if (handler == default_inout &&
            get_config_bool_default("x86.strictio", false))
                return (-1);

        flags = inout_handlers[port].flags;
        arg = inout_handlers[port].arg;

        if (in) {
                if (!(flags & IOPORT_F_IN))
                        return (-1);
        } else {
                if (!(flags & IOPORT_F_OUT))
                        return (-1);
        }

        retval = 0;
        if (vmexit->u.inout.string) {
                vis = &vmexit->u.inout_str;
                rep = vis->inout.rep;
                addrsize = vis->addrsize;
                prot = in ? PROT_WRITE : PROT_READ;
                assert(addrsize == 2 || addrsize == 4 || addrsize == 8);

                /* Index register */
                idxreg = in ? VM_REG_GUEST_RDI : VM_REG_GUEST_RSI;
                index = vis->index & vie_size2mask(addrsize);

                /* Count register */
                count = vis->count & vie_size2mask(addrsize);

                /* Limit number of back-to-back in/out emulations to 16 */
                iterations = MIN(count, 16);
                while (iterations > 0) {
                        assert(retval == 0);
                        if (vie_calculate_gla(vis->paging.cpu_mode,
                            vis->seg_name, &vis->seg_desc, index, bytes,
                            addrsize, prot, &gla)) {
                                vm_inject_gp(vcpu);
                                break;
                        }

                        error = vm_copy_setup(vcpu, &vis->paging, gla,
                            bytes, prot, iov, nitems(iov), &fault);
                        if (error) {
                                retval = -1;  /* Unrecoverable error */
                                break;
                        } else if (fault) {
                                retval = 0;  /* Resume guest to handle fault */
                                break;
                        }

                        if (vie_alignment_check(vis->paging.cpl, bytes,
                            vis->cr0, vis->rflags, gla)) {
                                vm_inject_ac(vcpu, 0);
                                break;
                        }

                        val = 0;
                        if (!in)
                                vm_copyin(iov, &val, bytes);

                        retval = handler(ctx, in, port, bytes, &val, arg);
                        if (retval != 0)
                                break;

                        if (in)
                                vm_copyout(&val, iov, bytes);

                        /* Update index */
                        if (vis->rflags & PSL_D)
                                index -= bytes;
                        else
                                index += bytes;

                        count--;
                        iterations--;
                }

                /* Update index register */
                error = vie_update_register(vcpu, idxreg, index, addrsize);
                assert(error == 0);

                /*
                 * Update count register only if the instruction had a repeat
                 * prefix.
                 */
                if (rep) {
                        error = vie_update_register(vcpu, VM_REG_GUEST_RCX,
                            count, addrsize);
                        assert(error == 0);
                }

                /* Restart the instruction if more iterations remain */
                if (retval == 0 && count != 0) {
                        error = vm_restart_instruction(vcpu);
                        assert(error == 0);
                }
        } else {
                eax = vmexit->u.inout.eax;
                val = eax & vie_size2mask(bytes);
                retval = handler(ctx, in, port, bytes, &val, arg);
                if (retval == 0 && in) {
                        eax &= ~vie_size2mask(bytes);
                        eax |= val & vie_size2mask(bytes);
                        error = vm_set_register(vcpu, VM_REG_GUEST_RAX,
                            eax);
                        assert(error == 0);
                }
        }
        return (retval);
}

void
init_inout(void)
{
        struct inout_port **iopp, *iop;

        /*
         * Set up the default handler for all ports
         */
        register_default_iohandler(0, MAX_IOPORTS);

        /*
         * Overwrite with specified handlers
         */
        SET_FOREACH(iopp, inout_port_set) {
                iop = *iopp;
                assert(iop->port < MAX_IOPORTS);
                inout_handlers[iop->port].name = iop->name;
                inout_handlers[iop->port].flags = iop->flags;
                inout_handlers[iop->port].handler = iop->handler;
                inout_handlers[iop->port].arg = NULL;
        }
}

int
register_inout(struct inout_port *iop)
{
        int i;

        VERIFY_IOPORT(iop->port, iop->size);

        /*
         * Verify that the new registration is not overwriting an already
         * allocated i/o range.
         */
        if ((iop->flags & IOPORT_F_DEFAULT) == 0) {
                for (i = iop->port; i < iop->port + iop->size; i++) {
                        if ((inout_handlers[i].flags & IOPORT_F_DEFAULT) == 0)
                                return (-1);
                }
        }

        for (i = iop->port; i < iop->port + iop->size; i++) {
                inout_handlers[i].name = iop->name;
                inout_handlers[i].flags = iop->flags;
                inout_handlers[i].handler = iop->handler;
                inout_handlers[i].arg = iop->arg;
        }

        return (0);
}

int
unregister_inout(struct inout_port *iop)
{

        VERIFY_IOPORT(iop->port, iop->size);
        assert(inout_handlers[iop->port].name == iop->name);

        register_default_iohandler(iop->port, iop->size);

        return (0);
}