/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2024-2025 Ruslan Bukin <br@bsdpad.com>
 *
 * This software was developed by the University of Cambridge Computer
 * Laboratory (Department of Computer Science and Technology) under Innovate
 * UK project 105694, "Digital Security by Design (DSbD) Technology Platform
 * Prototype".
 *
 * 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 AUTHOR AND CONTRIBUTORS ``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 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/kernel.h>
#include <sys/proc.h>

#include <machine/sbi.h>

#include <dev/vmm/vmm_vm.h>

#include "riscv.h"
#include "vmm_fence.h"

static int
vmm_sbi_handle_rfnc(struct vcpu *vcpu, struct hypctx *hypctx)
{
        struct vmm_fence fence;
        cpuset_t active_cpus;
        uint64_t hart_mask;
        uint64_t hart_mask_base;
        uint64_t func_id;
        struct hyp *hyp;
        uint16_t maxcpus;
        cpuset_t cpus;
        int i;

        func_id = hypctx->guest_regs.hyp_a[6];
        hart_mask = hypctx->guest_regs.hyp_a[0];
        hart_mask_base = hypctx->guest_regs.hyp_a[1];

        /* Construct vma_fence. */

        fence.start = hypctx->guest_regs.hyp_a[2];
        fence.size = hypctx->guest_regs.hyp_a[3];
        fence.asid = hypctx->guest_regs.hyp_a[4];

        switch (func_id) {
        case SBI_RFNC_REMOTE_FENCE_I:
                fence.type = VMM_RISCV_FENCE_I;
                break;
        case SBI_RFNC_REMOTE_SFENCE_VMA:
                fence.type = VMM_RISCV_FENCE_VMA;
                break;
        case SBI_RFNC_REMOTE_SFENCE_VMA_ASID:
                fence.type = VMM_RISCV_FENCE_VMA_ASID;
                break;
        default:
                return (SBI_ERR_NOT_SUPPORTED);
        }

        /* Construct cpuset_t from the mask supplied. */
        CPU_ZERO(&cpus);
        hyp = hypctx->hyp;
        active_cpus = vm_active_cpus(hyp->vm);
        maxcpus = vm_get_maxcpus(hyp->vm);
        for (i = 0; i < maxcpus; i++) {
                vcpu = vm_vcpu(hyp->vm, i);
                if (vcpu == NULL)
                        continue;
                if (hart_mask_base != -1UL) {
                        if (i < hart_mask_base)
                                continue;
                        if (!(hart_mask & (1UL << (i - hart_mask_base))))
                                continue;
                }
                /*
                 * If either hart_mask_base or at least one hartid from
                 * hart_mask is not valid, then return error.
                 */
                if (!CPU_ISSET(i, &active_cpus))
                        return (SBI_ERR_INVALID_PARAM);
                CPU_SET(i, &cpus);
        }

        if (CPU_EMPTY(&cpus))
                return (SBI_ERR_INVALID_PARAM);

        vmm_fence_add(hyp->vm, &cpus, &fence);

        return (SBI_SUCCESS);
}

static int
vmm_sbi_handle_time(struct vcpu *vcpu, struct hypctx *hypctx)
{
        uint64_t func_id;
        uint64_t next_val;

        func_id = hypctx->guest_regs.hyp_a[6];
        next_val = hypctx->guest_regs.hyp_a[0];

        switch (func_id) {
        case SBI_TIME_SET_TIMER:
                vtimer_set_timer(hypctx, next_val);
                break;
        default:
                return (SBI_ERR_NOT_SUPPORTED);
        }

        return (SBI_SUCCESS);
}

static int
vmm_sbi_handle_ipi(struct vcpu *vcpu, struct hypctx *hypctx)
{
        cpuset_t active_cpus;
        struct hyp *hyp;
        uint64_t hart_mask;
        uint64_t hart_mask_base;
        uint64_t func_id;
        cpuset_t cpus;
        int hart_id;
        int bit;

        func_id = hypctx->guest_regs.hyp_a[6];
        hart_mask = hypctx->guest_regs.hyp_a[0];
        hart_mask_base = hypctx->guest_regs.hyp_a[1];

        dprintf("%s: hart_mask %lx\n", __func__, hart_mask);

        hyp = hypctx->hyp;

        active_cpus = vm_active_cpus(hyp->vm);

        CPU_ZERO(&cpus);
        switch (func_id) {
        case SBI_IPI_SEND_IPI:
                while ((bit = ffs(hart_mask))) {
                        hart_id = (bit - 1);
                        hart_mask &= ~(1u << hart_id);
                        if (hart_mask_base != -1)
                                hart_id += hart_mask_base;
                        if (!CPU_ISSET(hart_id, &active_cpus))
                                return (SBI_ERR_INVALID_PARAM);
                        CPU_SET(hart_id, &cpus);
                }
                break;
        default:
                dprintf("%s: unknown func %ld\n", __func__, func_id);
                return (SBI_ERR_NOT_SUPPORTED);
        }

        if (CPU_EMPTY(&cpus))
                return (SBI_ERR_INVALID_PARAM);

        riscv_send_ipi(hyp, &cpus);

        return (SBI_SUCCESS);
}

bool
vmm_sbi_ecall(struct vcpu *vcpu)
{
        int sbi_extension_id;
        struct hypctx *hypctx;
        int error;

        hypctx = riscv_get_active_vcpu();
        sbi_extension_id = hypctx->guest_regs.hyp_a[7];

        dprintf("%s: args %lx %lx %lx %lx %lx %lx %lx %lx\n", __func__,
            hypctx->guest_regs.hyp_a[0],
            hypctx->guest_regs.hyp_a[1],
            hypctx->guest_regs.hyp_a[2],
            hypctx->guest_regs.hyp_a[3],
            hypctx->guest_regs.hyp_a[4],
            hypctx->guest_regs.hyp_a[5],
            hypctx->guest_regs.hyp_a[6],
            hypctx->guest_regs.hyp_a[7]);

        switch (sbi_extension_id) {
        case SBI_EXT_ID_RFNC:
                error = vmm_sbi_handle_rfnc(vcpu, hypctx);
                break;
        case SBI_EXT_ID_TIME:
                error = vmm_sbi_handle_time(vcpu, hypctx);
                break;
        case SBI_EXT_ID_IPI:
                error = vmm_sbi_handle_ipi(vcpu, hypctx);
                break;
        default:
                /* Return to handle in userspace. */
                return (false);
        }

        hypctx->guest_regs.hyp_a[0] = error;

        /* Request is handled in kernel mode. */
        return (true);
}