/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2013 Anish Gupta (akgupt3@gmail.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 unmodified, 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 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/cdefs.h>
#include "opt_bhyve_snapshot.h"

#include <sys/param.h>
#include <sys/systm.h>

#include <machine/segments.h>
#include <machine/specialreg.h>
#include <machine/vmm.h>
#include <machine/vmm_snapshot.h>

#include <dev/vmm/vmm_ktr.h>

#include "vlapic.h"
#include "vmcb.h"
#include "svm.h"
#include "svm_softc.h"

/*
 * The VMCB aka Virtual Machine Control Block is a 4KB aligned page
 * in memory that describes the virtual machine.
 *
 * The VMCB contains:
 * - instructions or events in the guest to intercept
 * - control bits that modify execution environment of the guest
 * - guest processor state (e.g. general purpose registers)
 */

/*
 * Return VMCB segment area.
 */
static struct vmcb_segment *
vmcb_segptr(struct vmcb *vmcb, int type)
{
        struct vmcb_state *state;
        struct vmcb_segment *seg;

        state = &vmcb->state;

        switch (type) {
        case VM_REG_GUEST_CS:
                seg = &state->cs;
                break;

        case VM_REG_GUEST_DS:
                seg = &state->ds;
                break;

        case VM_REG_GUEST_ES:
                seg = &state->es;
                break;

        case VM_REG_GUEST_FS:
                seg = &state->fs;
                break;

        case VM_REG_GUEST_GS:
                seg = &state->gs;
                break;

        case VM_REG_GUEST_SS:
                seg = &state->ss;
                break;

        case VM_REG_GUEST_GDTR:
                seg = &state->gdt;
                break;

        case VM_REG_GUEST_IDTR:
                seg = &state->idt;
                break;

        case VM_REG_GUEST_LDTR:
                seg = &state->ldt;
                break;

        case VM_REG_GUEST_TR:
                seg = &state->tr;
                break;

        default:
                seg = NULL;
                break;
        }

        return (seg);
}

static int
vmcb_access(struct svm_vcpu *vcpu, int write, int ident, uint64_t *val)
{
        struct vmcb *vmcb;
        int off, bytes;
        char *ptr;

        vmcb    = svm_get_vmcb(vcpu);
        off     = VMCB_ACCESS_OFFSET(ident);
        bytes   = VMCB_ACCESS_BYTES(ident);

        if ((off + bytes) >= sizeof (struct vmcb))
                return (EINVAL);

        ptr = (char *)vmcb;

        if (!write)
                *val = 0;

        switch (bytes) {
        case 8:
        case 4:
        case 2:
        case 1:
                if (write)
                        memcpy(ptr + off, val, bytes);
                else
                        memcpy(val, ptr + off, bytes);
                break;
        default:
                SVM_CTR1(vcpu, "Invalid size %d for VMCB access: %d", bytes);
                return (EINVAL);
        }

        /* Invalidate all VMCB state cached by h/w. */
        if (write)
                svm_set_dirty(vcpu, 0xffffffff);

        return (0);
}

/*
 * Read from segment selector, control and general purpose register of VMCB.
 */
int
vmcb_read(struct svm_vcpu *vcpu, int ident, uint64_t *retval)
{
        struct vmcb *vmcb;
        struct vmcb_state *state;
        struct vmcb_segment *seg;
        int err;

        vmcb = svm_get_vmcb(vcpu);
        state = &vmcb->state;
        err = 0;

        if (VMCB_ACCESS_OK(ident))
                return (vmcb_access(vcpu, 0, ident, retval));

        switch (ident) {
        case VM_REG_GUEST_CR0:
                *retval = state->cr0;
                break;

        case VM_REG_GUEST_CR2:
                *retval = state->cr2;
                break;

        case VM_REG_GUEST_CR3:
                *retval = state->cr3;
                break;

        case VM_REG_GUEST_CR4:
                *retval = state->cr4;
                break;

        case VM_REG_GUEST_DR6:
                *retval = state->dr6;
                break;

        case VM_REG_GUEST_DR7:
                *retval = state->dr7;
                break;

        case VM_REG_GUEST_EFER:
                *retval = state->efer;
                break;

        case VM_REG_GUEST_RAX:
                *retval = state->rax;
                break;

        case VM_REG_GUEST_RFLAGS:
                *retval = state->rflags;
                break;

        case VM_REG_GUEST_RIP:
                *retval = state->rip;
                break;

        case VM_REG_GUEST_RSP:
                *retval = state->rsp;
                break;

        case VM_REG_GUEST_CS:
        case VM_REG_GUEST_DS:
        case VM_REG_GUEST_ES:
        case VM_REG_GUEST_FS:
        case VM_REG_GUEST_GS:
        case VM_REG_GUEST_SS:
        case VM_REG_GUEST_LDTR:
        case VM_REG_GUEST_TR:
                seg = vmcb_segptr(vmcb, ident);
                KASSERT(seg != NULL, ("%s: unable to get segment %d from VMCB",
                    __func__, ident));
                *retval = seg->selector;
                break;

        case VM_REG_GUEST_FS_BASE:
        case VM_REG_GUEST_GS_BASE:
                seg = vmcb_segptr(vmcb, ident == VM_REG_GUEST_FS_BASE ?
                    VM_REG_GUEST_FS : VM_REG_GUEST_GS);
                KASSERT(seg != NULL, ("%s: unable to get segment %d from VMCB",
                    __func__, ident));
                *retval = seg->base;
                break;
        case VM_REG_GUEST_KGS_BASE:
                *retval = state->kernelgsbase;
                break;

        case VM_REG_GUEST_TPR:
                *retval = vlapic_get_cr8(vm_lapic(vcpu->vcpu));
                break;

        case VM_REG_GUEST_GDTR:
        case VM_REG_GUEST_IDTR:
                /* GDTR and IDTR don't have segment selectors */
                err = EINVAL;
                break;
        default:
                err =  EINVAL;
                break;
        }

        return (err);
}

/*
 * Write to segment selector, control and general purpose register of VMCB.
 */
int
vmcb_write(struct svm_vcpu *vcpu, int ident, uint64_t val)
{
        struct vmcb *vmcb;
        struct vmcb_state *state;
        struct vmcb_segment *seg;
        int err, dirtyseg;

        vmcb = svm_get_vmcb(vcpu);
        state = &vmcb->state;
        dirtyseg = 0;
        err = 0;

        if (VMCB_ACCESS_OK(ident))
                return (vmcb_access(vcpu, 1, ident, &val));

        switch (ident) {
        case VM_REG_GUEST_CR0:
                state->cr0 = val;
                svm_set_dirty(vcpu, VMCB_CACHE_CR);
                break;

        case VM_REG_GUEST_CR2:
                state->cr2 = val;
                svm_set_dirty(vcpu, VMCB_CACHE_CR2);
                break;

        case VM_REG_GUEST_CR3:
                state->cr3 = val;
                svm_set_dirty(vcpu, VMCB_CACHE_CR);
                break;

        case VM_REG_GUEST_CR4:
                state->cr4 = val;
                svm_set_dirty(vcpu, VMCB_CACHE_CR);
                break;

        case VM_REG_GUEST_DR6:
                state->dr6 = val;
                svm_set_dirty(vcpu, VMCB_CACHE_DR);
                break;

        case VM_REG_GUEST_DR7:
                state->dr7 = val;
                svm_set_dirty(vcpu, VMCB_CACHE_DR);
                break;

        case VM_REG_GUEST_EFER:
                /* EFER_SVM must always be set when the guest is executing */
                state->efer = val | EFER_SVM;
                svm_set_dirty(vcpu, VMCB_CACHE_CR);
                break;

        case VM_REG_GUEST_RAX:
                state->rax = val;
                break;

        case VM_REG_GUEST_RFLAGS:
                state->rflags = val;
                break;

        case VM_REG_GUEST_RIP:
                state->rip = val;
                break;

        case VM_REG_GUEST_RSP:
                state->rsp = val;
                break;

        case VM_REG_GUEST_CS:
        case VM_REG_GUEST_DS:
        case VM_REG_GUEST_ES:
        case VM_REG_GUEST_SS:
                dirtyseg = 1;           /* FALLTHROUGH */
        case VM_REG_GUEST_FS:
        case VM_REG_GUEST_GS:
        case VM_REG_GUEST_LDTR:
        case VM_REG_GUEST_TR:
                seg = vmcb_segptr(vmcb, ident);
                KASSERT(seg != NULL, ("%s: unable to get segment %d from VMCB",
                    __func__, ident));
                seg->selector = val;
                if (dirtyseg)
                        svm_set_dirty(vcpu, VMCB_CACHE_SEG);
                break;

        case VM_REG_GUEST_GDTR:
        case VM_REG_GUEST_IDTR:
                /* GDTR and IDTR don't have segment selectors */
                err = EINVAL;
                break;
        default:
                err = EINVAL;
                break;
        }

        return (err);
}

int
vmcb_seg(struct vmcb *vmcb, int ident, struct vmcb_segment *seg2)
{
        struct vmcb_segment *seg;

        seg = vmcb_segptr(vmcb, ident);
        if (seg != NULL) {
                bcopy(seg, seg2, sizeof(struct vmcb_segment));
                return (0);
        } else {
                return (EINVAL);
        }
}

int
vmcb_setdesc(struct svm_vcpu *vcpu, int reg, struct seg_desc *desc)
{
        struct vmcb *vmcb;
        struct vmcb_segment *seg;
        uint16_t attrib;

        vmcb = svm_get_vmcb(vcpu);

        seg = vmcb_segptr(vmcb, reg);
        KASSERT(seg != NULL, ("%s: invalid segment descriptor %d",
            __func__, reg));

        seg->base = desc->base;
        seg->limit = desc->limit;
        if (reg != VM_REG_GUEST_GDTR && reg != VM_REG_GUEST_IDTR) {
                /*
                 * Map seg_desc access to VMCB attribute format.
                 *
                 * SVM uses the 'P' bit in the segment attributes to indicate a
                 * NULL segment so clear it if the segment is marked unusable.
                 */
                attrib = ((desc->access & 0xF000) >> 4) | (desc->access & 0xFF);
                if (SEG_DESC_UNUSABLE(desc->access)) {
                        attrib &= ~0x80;
                }
                seg->attrib = attrib;
        }

        SVM_CTR4(vcpu, "Setting desc %d: base (%#lx), limit (%#x), "
            "attrib (%#x)", reg, seg->base, seg->limit, seg->attrib);

        switch (reg) {
        case VM_REG_GUEST_CS:
        case VM_REG_GUEST_DS:
        case VM_REG_GUEST_ES:
        case VM_REG_GUEST_SS:
                svm_set_dirty(vcpu, VMCB_CACHE_SEG);
                break;
        case VM_REG_GUEST_GDTR:
        case VM_REG_GUEST_IDTR:
                svm_set_dirty(vcpu, VMCB_CACHE_DT);
                break;
        default:
                break;
        }

        return (0);
}

int
vmcb_getdesc(struct svm_vcpu *vcpu, int reg, struct seg_desc *desc)
{
        struct vmcb *vmcb;
        struct vmcb_segment *seg;

        vmcb = svm_get_vmcb(vcpu);
        seg = vmcb_segptr(vmcb, reg);
        KASSERT(seg != NULL, ("%s: invalid segment descriptor %d",
            __func__, reg));

        desc->base = seg->base;
        desc->limit = seg->limit;
        desc->access = 0;

        if (reg != VM_REG_GUEST_GDTR && reg != VM_REG_GUEST_IDTR) {
                /* Map seg_desc access to VMCB attribute format */
                desc->access = ((seg->attrib & 0xF00) << 4) |
                    (seg->attrib & 0xFF);

                /*
                 * VT-x uses bit 16 to indicate a segment that has been loaded
                 * with a NULL selector (aka unusable). The 'desc->access'
                 * field is interpreted in the VT-x format by the
                 * processor-independent code.
                 *
                 * SVM uses the 'P' bit to convey the same information so
                 * convert it into the VT-x format. For more details refer to
                 * section "Segment State in the VMCB" in APMv2.
                 */
                if (reg != VM_REG_GUEST_CS && reg != VM_REG_GUEST_TR) {
                        if ((desc->access & 0x80) == 0)
                                desc->access |= 0x10000;  /* Unusable segment */
                }
        }

        return (0);
}

#ifdef BHYVE_SNAPSHOT
int
vmcb_getany(struct svm_vcpu *vcpu, int ident, uint64_t *val)
{
        int error = 0;

        if (ident >= VM_REG_LAST) {
                error = EINVAL;
                goto err;
        }

        error = vmcb_read(vcpu, ident, val);

err:
        return (error);
}

int
vmcb_setany(struct svm_vcpu *vcpu, int ident, uint64_t val)
{
        int error = 0;

        if (ident >= VM_REG_LAST) {
                error = EINVAL;
                goto err;
        }

        error = vmcb_write(vcpu, ident, val);

err:
        return (error);
}

int
vmcb_snapshot_desc(struct svm_vcpu *vcpu, int reg,
    struct vm_snapshot_meta *meta)
{
        int ret;
        struct seg_desc desc;

        if (meta->op == VM_SNAPSHOT_SAVE) {
                ret = vmcb_getdesc(vcpu, reg, &desc);
                if (ret != 0)
                        goto done;

                SNAPSHOT_VAR_OR_LEAVE(desc.base, meta, ret, done);
                SNAPSHOT_VAR_OR_LEAVE(desc.limit, meta, ret, done);
                SNAPSHOT_VAR_OR_LEAVE(desc.access, meta, ret, done);
        } else if (meta->op == VM_SNAPSHOT_RESTORE) {
                SNAPSHOT_VAR_OR_LEAVE(desc.base, meta, ret, done);
                SNAPSHOT_VAR_OR_LEAVE(desc.limit, meta, ret, done);
                SNAPSHOT_VAR_OR_LEAVE(desc.access, meta, ret, done);

                ret = vmcb_setdesc(vcpu, reg, &desc);
                if (ret != 0)
                        goto done;
        } else {
                ret = EINVAL;
                goto done;
        }

done:
        return (ret);
}

int
vmcb_snapshot_any(struct svm_vcpu *vcpu, int ident,
    struct vm_snapshot_meta *meta)
{
        int ret;
        uint64_t val;

        if (meta->op == VM_SNAPSHOT_SAVE) {
                ret = vmcb_getany(vcpu, ident, &val);
                if (ret != 0)
                        goto done;

                SNAPSHOT_VAR_OR_LEAVE(val, meta, ret, done);
        } else if (meta->op == VM_SNAPSHOT_RESTORE) {
                SNAPSHOT_VAR_OR_LEAVE(val, meta, ret, done);

                ret = vmcb_setany(vcpu, ident, val);
                if (ret != 0)
                        goto done;
        } else {
                ret = EINVAL;
                goto done;
        }

done:
        return (ret);
}
#endif