// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2012 - Virtual Open Systems and Columbia University
 * Author: Christoffer Dall <c.dall@virtualopensystems.com>
 */

#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include <asm/kvm_emulate.h>
#include <asm/kvm_coproc.h>
#include <asm/kvm_mmu.h>
#include <kvm/arm_psci.h>
#include <trace/events/kvm.h>

#include "trace.h"

typedef int (*exit_handle_fn)(struct kvm_vcpu *, struct kvm_run *);

static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
        int ret;

        trace_kvm_hvc(*vcpu_pc(vcpu), *vcpu_reg(vcpu, 0),
                      kvm_vcpu_hvc_get_imm(vcpu));
        vcpu->stat.hvc_exit_stat++;

        ret = kvm_hvc_call_handler(vcpu);
        if (ret < 0) {
                vcpu_set_reg(vcpu, 0, ~0UL);
                return 1;
        }

        return ret;
}

static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
        /*
         * "If an SMC instruction executed at Non-secure EL1 is
         * trapped to EL2 because HCR_EL2.TSC is 1, the exception is a
         * Trap exception, not a Secure Monitor Call exception [...]"
         *
         * We need to advance the PC after the trap, as it would
         * otherwise return to the same address...
         */
        vcpu_set_reg(vcpu, 0, ~0UL);
        kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
        return 1;
}

/**
 * kvm_handle_wfx - handle a WFI or WFE instructions trapped in guests
 * @vcpu:       the vcpu pointer
 * @run:        the kvm_run structure pointer
 *
 * WFE: Yield the CPU and come back to this vcpu when the scheduler
 * decides to.
 * WFI: Simply call kvm_vcpu_block(), which will halt execution of
 * world-switches and schedule other host processes until there is an
 * incoming IRQ or FIQ to the VM.
 */
static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
        if (kvm_vcpu_get_hsr(vcpu) & HSR_WFI_IS_WFE) {
                trace_kvm_wfx(*vcpu_pc(vcpu), true);
                vcpu->stat.wfe_exit_stat++;
                kvm_vcpu_on_spin(vcpu, vcpu_mode_priv(vcpu));
        } else {
                trace_kvm_wfx(*vcpu_pc(vcpu), false);
                vcpu->stat.wfi_exit_stat++;
                kvm_vcpu_block(vcpu);
                kvm_clear_request(KVM_REQ_UNHALT, vcpu);
        }

        kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));

        return 1;
}

static int kvm_handle_unknown_ec(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
        u32 hsr = kvm_vcpu_get_hsr(vcpu);

        kvm_pr_unimpl("Unknown exception class: hsr: %#08x\n",
                      hsr);

        kvm_inject_undefined(vcpu);
        return 1;
}

static exit_handle_fn arm_exit_handlers[] = {
        [0 ... HSR_EC_MAX]      = kvm_handle_unknown_ec,
        [HSR_EC_WFI]            = kvm_handle_wfx,
        [HSR_EC_CP15_32]        = kvm_handle_cp15_32,
        [HSR_EC_CP15_64]        = kvm_handle_cp15_64,
        [HSR_EC_CP14_MR]        = kvm_handle_cp14_32,
        [HSR_EC_CP14_LS]        = kvm_handle_cp14_load_store,
        [HSR_EC_CP14_64]        = kvm_handle_cp14_64,
        [HSR_EC_CP_0_13]        = kvm_handle_cp_0_13_access,
        [HSR_EC_CP10_ID]        = kvm_handle_cp10_id,
        [HSR_EC_HVC]            = handle_hvc,
        [HSR_EC_SMC]            = handle_smc,
        [HSR_EC_IABT]           = kvm_handle_guest_abort,
        [HSR_EC_DABT]           = kvm_handle_guest_abort,
};

static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu)
{
        u8 hsr_ec = kvm_vcpu_trap_get_class(vcpu);

        return arm_exit_handlers[hsr_ec];
}

/*
 * Return > 0 to return to guest, < 0 on error, 0 (and set exit_reason) on
 * proper exit to userspace.
 */
int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
                       int exception_index)
{
        exit_handle_fn exit_handler;

        if (ARM_ABORT_PENDING(exception_index)) {
                u8 hsr_ec = kvm_vcpu_trap_get_class(vcpu);

                /*
                 * HVC/SMC already have an adjusted PC, which we need
                 * to correct in order to return to after having
                 * injected the abort.
                 */
                if (hsr_ec == HSR_EC_HVC || hsr_ec == HSR_EC_SMC) {
                        u32 adj =  kvm_vcpu_trap_il_is32bit(vcpu) ? 4 : 2;
                        *vcpu_pc(vcpu) -= adj;
                }

                kvm_inject_vabt(vcpu);
                return 1;
        }

        exception_index = ARM_EXCEPTION_CODE(exception_index);

        switch (exception_index) {
        case ARM_EXCEPTION_IRQ:
                return 1;
        case ARM_EXCEPTION_HVC:
                /*
                 * See ARM ARM B1.14.1: "Hyp traps on instructions
                 * that fail their condition code check"
                 */
                if (!kvm_condition_valid(vcpu)) {
                        kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
                        return 1;
                }

                exit_handler = kvm_get_exit_handler(vcpu);

                return exit_handler(vcpu, run);
        case ARM_EXCEPTION_DATA_ABORT:
                kvm_inject_vabt(vcpu);
                return 1;
        case ARM_EXCEPTION_HYP_GONE:
                /*
                 * HYP has been reset to the hyp-stub. This happens
                 * when a guest is pre-empted by kvm_reboot()'s
                 * shutdown call.
                 */
                run->exit_reason = KVM_EXIT_FAIL_ENTRY;
                return 0;
        default:
                kvm_pr_unimpl("Unsupported exception type: %d",
                              exception_index);
                run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
                return 0;
        }
}