/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2014 Tycho Nightingale <tycho.nightingale@pluribusnetworks.com>
 * 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 THE AUTHOR ``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 THE AUTHOR 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/systm.h>

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

#include <dev/vmm/vmm_ktr.h>
#include <dev/vmm/vmm_vm.h>

#include "vatpic.h"
#include "vatpit.h"
#include "vpmtmr.h"
#include "vrtc.h"
#include "vmm_ioport.h"

#define MAX_IOPORTS             1280

ioport_handler_func_t ioport_handler[MAX_IOPORTS] = {
        [TIMER_MODE] = vatpit_handler,
        [TIMER_CNTR0] = vatpit_handler,
        [TIMER_CNTR1] = vatpit_handler,
        [TIMER_CNTR2] = vatpit_handler,
        [NMISC_PORT] = vatpit_nmisc_handler,
        [IO_ICU1] = vatpic_master_handler,
        [IO_ICU1 + ICU_IMR_OFFSET] = vatpic_master_handler,
        [IO_ICU2] = vatpic_slave_handler,
        [IO_ICU2 + ICU_IMR_OFFSET] = vatpic_slave_handler,
        [IO_ELCR1] = vatpic_elc_handler,
        [IO_ELCR2] = vatpic_elc_handler,
        [IO_PMTMR] = vpmtmr_handler,
        [IO_RTC] = vrtc_addr_handler,
        [IO_RTC + 1] = vrtc_data_handler,
};

#ifdef KTR
static const char *
inout_instruction(struct vm_exit *vmexit)
{
        int index;

        static const char *iodesc[] = {
                "outb", "outw", "outl",
                "inb", "inw", "inl",
                "outsb", "outsw", "outsd",
                "insb", "insw", "insd",
        };

        switch (vmexit->u.inout.bytes) {
        case 1:
                index = 0;
                break;
        case 2:
                index = 1;
                break;
        default:
                index = 2;
                break;
        }

        if (vmexit->u.inout.in)
                index += 3;

        if (vmexit->u.inout.string)
                index += 6;

        KASSERT(index < nitems(iodesc), ("%s: invalid index %d",
            __func__, index));

        return (iodesc[index]);
}
#endif  /* KTR */

static int
emulate_inout_port(struct vcpu *vcpu, struct vm_exit *vmexit, bool *retu)
{
        ioport_handler_func_t handler;
        uint32_t mask, val = 0;
        int error;

        /*
         * If there is no handler for the I/O port then punt to userspace.
         */
        if (vmexit->u.inout.port >= MAX_IOPORTS ||
            (handler = ioport_handler[vmexit->u.inout.port]) == NULL) {
                *retu = true;
                return (0);
        }

        mask = vie_size2mask(vmexit->u.inout.bytes);

        if (!vmexit->u.inout.in) {
                val = vmexit->u.inout.eax & mask;
        }

        error = (*handler)(vcpu_vm(vcpu), vmexit->u.inout.in,
            vmexit->u.inout.port, vmexit->u.inout.bytes, &val);
        if (error) {
                /*
                 * The value returned by this function is also the return value
                 * of vm_run(). This needs to be a positive number otherwise it
                 * can be interpreted as a "pseudo-error" like ERESTART.
                 *
                 * Enforce this by mapping all errors to EIO.
                 */
                return (EIO);
        }

        if (vmexit->u.inout.in) {
                vmexit->u.inout.eax &= ~mask;
                vmexit->u.inout.eax |= val & mask;
                error = vm_set_register(vcpu, VM_REG_GUEST_RAX,
                    vmexit->u.inout.eax);
                KASSERT(error == 0, ("emulate_ioport: error %d setting guest "
                    "rax register", error));
        }
        *retu = false;
        return (0);
}

static int
decode_segment(struct vcpu *vcpu, enum vm_reg_name *segment)
{
        struct vm_guest_paging *paging;
        struct vie vie;
        struct vm_exit *vme;
        int err;
        int fault;

        vme = vm_exitinfo(vcpu);
        paging = &vme->u.inout_str.paging;

        vie_init(&vie, NULL, 0);
        err = vmm_fetch_instruction(vcpu, paging,
            vme->rip + vme->u.inout_str.cs_base, VIE_INST_SIZE, &vie, &fault);
        if (err || fault)
                return (err);

        err = vmm_decode_instruction(vcpu, VIE_INVALID_GLA, paging->cpu_mode,
            vme->u.inout_str.cs_d, &vie);

        if (err || vie.op.op_type != VIE_OP_TYPE_OUTS)
                return (EINVAL);
        if (vie.segment_override)
                *segment = vie.segment_register;
        else
                *segment = VM_REG_GUEST_DS;

        return (0);
}

static int
emulate_inout_str(struct vcpu *vcpu, struct vm_exit *vmexit, bool *retu)
{
        int err;

        *retu = true;
        if (vmexit->u.inout_str.seg_name == VM_REG_LAST) {
                err = decode_segment(vcpu, &vmexit->u.inout_str.seg_name);
                if (err)
                        return (err);
                return (vm_get_seg_desc(vcpu, vmexit->u.inout_str.seg_name,
                    &vmexit->u.inout_str.seg_desc));
        }
        return (0);     /* Return to userspace to finish emulation */
}

int
vm_handle_inout(struct vcpu *vcpu, struct vm_exit *vmexit, bool *retu)
{
        int bytes __diagused, error;

        bytes = vmexit->u.inout.bytes;
        KASSERT(bytes == 1 || bytes == 2 || bytes == 4,
            ("vm_handle_inout: invalid operand size %d", bytes));

        if (vmexit->u.inout.string)
                error = emulate_inout_str(vcpu, vmexit, retu);
        else
                error = emulate_inout_port(vcpu, vmexit, retu);

        VCPU_CTR4(vcpu_vm(vcpu), vcpu_vcpuid(vcpu), "%s%s 0x%04x: %s",
            vmexit->u.inout.rep ? "rep " : "",
            inout_instruction(vmexit),
            vmexit->u.inout.port,
            error ? "error" : (*retu ? "userspace" : "handled"));

        return (error);
}