/*
 * Copyright (C) 2012 - Virtual Open Systems and Columbia University
 * Author: Christoffer Dall <c.dall@virtualopensystems.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2, as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

#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 <asm/kvm_psci.h>
#include <trace/events/kvm.h>

#include "trace.h"

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

static int handle_svc_hyp(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
        /* SVC called from Hyp mode should never get here */
        kvm_debug("SVC called from Hyp mode shouldn't go here\n");
        BUG();
        return -EINVAL; /* Squash warning */
}

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));

        ret = kvm_psci_call(vcpu);
        if (ret < 0) {
                kvm_inject_undefined(vcpu);
                return 1;
        }

        return ret;
}

static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
        kvm_inject_undefined(vcpu);
        return 1;
}

static int handle_pabt_hyp(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
        /* The hypervisor should never cause aborts */
        kvm_err("Prefetch Abort taken from Hyp mode at %#08lx (HSR: %#08x)\n",
                kvm_vcpu_get_hfar(vcpu), kvm_vcpu_get_hsr(vcpu));
        return -EFAULT;
}

static int handle_dabt_hyp(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
        /* This is either an error in the ws. code or an external abort */
        kvm_err("Data Abort taken from Hyp mode at %#08lx (HSR: %#08x)\n",
                kvm_vcpu_get_hfar(vcpu), kvm_vcpu_get_hsr(vcpu));
        return -EFAULT;
}

/**
 * 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);
                kvm_vcpu_on_spin(vcpu);
        } else {
                trace_kvm_wfx(*vcpu_pc(vcpu), false);
                kvm_vcpu_block(vcpu);
        }

        kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));

        return 1;
}

static exit_handle_fn arm_exit_handlers[] = {
        [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_access,
        [HSR_EC_CP14_LS]        = kvm_handle_cp14_load_store,
        [HSR_EC_CP14_64]        = kvm_handle_cp14_access,
        [HSR_EC_CP_0_13]        = kvm_handle_cp_0_13_access,
        [HSR_EC_CP10_ID]        = kvm_handle_cp10_id,
        [HSR_EC_SVC_HYP]        = handle_svc_hyp,
        [HSR_EC_HVC]            = handle_hvc,
        [HSR_EC_SMC]            = handle_smc,
        [HSR_EC_IABT]           = kvm_handle_guest_abort,
        [HSR_EC_IABT_HYP]       = handle_pabt_hyp,
        [HSR_EC_DABT]           = kvm_handle_guest_abort,
        [HSR_EC_DABT_HYP]       = handle_dabt_hyp,
};

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

        if (hsr_ec >= ARRAY_SIZE(arm_exit_handlers) ||
            !arm_exit_handlers[hsr_ec]) {
                kvm_err("Unknown exception class: hsr: %#08x\n",
                        (unsigned int)kvm_vcpu_get_hsr(vcpu));
                BUG();
        }

        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;

        switch (exception_index) {
        case ARM_EXCEPTION_IRQ:
                return 1;
        case ARM_EXCEPTION_UNDEFINED:
                kvm_err("Undefined exception in Hyp mode at: %#08lx\n",
                        kvm_vcpu_get_hyp_pc(vcpu));
                BUG();
                panic("KVM: Hypervisor undefined exception!\n");
        case ARM_EXCEPTION_DATA_ABORT:
        case ARM_EXCEPTION_PREF_ABORT:
        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);
        default:
                kvm_pr_unimpl("Unsupported exception type: %d",
                              exception_index);
                run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
                return 0;
        }
}