/*
 * in-kernel handling for sie intercepts
 *
 * Copyright IBM Corp. 2008, 2014
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License (version 2 only)
 * as published by the Free Software Foundation.
 *
 *    Author(s): Carsten Otte <cotte@de.ibm.com>
 *               Christian Borntraeger <borntraeger@de.ibm.com>
 */

#include <linux/kvm_host.h>
#include <linux/errno.h>
#include <linux/pagemap.h>

#include <asm/kvm_host.h>
#include <asm/asm-offsets.h>
#include <asm/irq.h>

#include "kvm-s390.h"
#include "gaccess.h"
#include "trace.h"
#include "trace-s390.h"


static const intercept_handler_t instruction_handlers[256] = {
        [0x01] = kvm_s390_handle_01,
        [0x82] = kvm_s390_handle_lpsw,
        [0x83] = kvm_s390_handle_diag,
        [0xae] = kvm_s390_handle_sigp,
        [0xb2] = kvm_s390_handle_b2,
        [0xb6] = kvm_s390_handle_stctl,
        [0xb7] = kvm_s390_handle_lctl,
        [0xb9] = kvm_s390_handle_b9,
        [0xe5] = kvm_s390_handle_e5,
        [0xeb] = kvm_s390_handle_eb,
};

void kvm_s390_rewind_psw(struct kvm_vcpu *vcpu, int ilc)
{
        struct kvm_s390_sie_block *sie_block = vcpu->arch.sie_block;

        /* Use the length of the EXECUTE instruction if necessary */
        if (sie_block->icptstatus & 1) {
                ilc = (sie_block->icptstatus >> 4) & 0x6;
                if (!ilc)
                        ilc = 4;
        }
        sie_block->gpsw.addr = __rewind_psw(sie_block->gpsw, ilc);
}

static int handle_noop(struct kvm_vcpu *vcpu)
{
        switch (vcpu->arch.sie_block->icptcode) {
        case 0x0:
                vcpu->stat.exit_null++;
                break;
        case 0x10:
                vcpu->stat.exit_external_request++;
                break;
        default:
                break; /* nothing */
        }
        return 0;
}

static int handle_stop(struct kvm_vcpu *vcpu)
{
        struct kvm_s390_local_interrupt *li = &vcpu->arch.local_int;
        int rc = 0;
        uint8_t flags, stop_pending;

        vcpu->stat.exit_stop_request++;

        /* delay the stop if any non-stop irq is pending */
        if (kvm_s390_vcpu_has_irq(vcpu, 1))
                return 0;

        /* avoid races with the injection/SIGP STOP code */
        spin_lock(&li->lock);
        flags = li->irq.stop.flags;
        stop_pending = kvm_s390_is_stop_irq_pending(vcpu);
        spin_unlock(&li->lock);

        trace_kvm_s390_stop_request(stop_pending, flags);
        if (!stop_pending)
                return 0;

        if (flags & KVM_S390_STOP_FLAG_STORE_STATUS) {
                rc = kvm_s390_vcpu_store_status(vcpu,
                                                KVM_S390_STORE_STATUS_NOADDR);
                if (rc)
                        return rc;
        }

        if (!kvm_s390_user_cpu_state_ctrl(vcpu->kvm))
                kvm_s390_vcpu_stop(vcpu);
        return -EOPNOTSUPP;
}

static int handle_validity(struct kvm_vcpu *vcpu)
{
        int viwhy = vcpu->arch.sie_block->ipb >> 16;

        vcpu->stat.exit_validity++;
        trace_kvm_s390_intercept_validity(vcpu, viwhy);
        WARN_ONCE(true, "kvm: unhandled validity intercept 0x%x\n", viwhy);
        return -EOPNOTSUPP;
}

static int handle_instruction(struct kvm_vcpu *vcpu)
{
        intercept_handler_t handler;

        vcpu->stat.exit_instruction++;
        trace_kvm_s390_intercept_instruction(vcpu,
                                             vcpu->arch.sie_block->ipa,
                                             vcpu->arch.sie_block->ipb);
        handler = instruction_handlers[vcpu->arch.sie_block->ipa >> 8];
        if (handler)
                return handler(vcpu);
        return -EOPNOTSUPP;
}

static void __extract_prog_irq(struct kvm_vcpu *vcpu,
                               struct kvm_s390_pgm_info *pgm_info)
{
        memset(pgm_info, 0, sizeof(struct kvm_s390_pgm_info));
        pgm_info->code = vcpu->arch.sie_block->iprcc;

        switch (vcpu->arch.sie_block->iprcc & ~PGM_PER) {
        case PGM_AFX_TRANSLATION:
        case PGM_ASX_TRANSLATION:
        case PGM_EX_TRANSLATION:
        case PGM_LFX_TRANSLATION:
        case PGM_LSTE_SEQUENCE:
        case PGM_LSX_TRANSLATION:
        case PGM_LX_TRANSLATION:
        case PGM_PRIMARY_AUTHORITY:
        case PGM_SECONDARY_AUTHORITY:
        case PGM_SPACE_SWITCH:
                pgm_info->trans_exc_code = vcpu->arch.sie_block->tecmc;
                break;
        case PGM_ALEN_TRANSLATION:
        case PGM_ALE_SEQUENCE:
        case PGM_ASTE_INSTANCE:
        case PGM_ASTE_SEQUENCE:
        case PGM_ASTE_VALIDITY:
        case PGM_EXTENDED_AUTHORITY:
                pgm_info->exc_access_id = vcpu->arch.sie_block->eai;
                break;
        case PGM_ASCE_TYPE:
        case PGM_PAGE_TRANSLATION:
        case PGM_REGION_FIRST_TRANS:
        case PGM_REGION_SECOND_TRANS:
        case PGM_REGION_THIRD_TRANS:
        case PGM_SEGMENT_TRANSLATION:
                pgm_info->trans_exc_code = vcpu->arch.sie_block->tecmc;
                pgm_info->exc_access_id  = vcpu->arch.sie_block->eai;
                pgm_info->op_access_id  = vcpu->arch.sie_block->oai;
                break;
        case PGM_MONITOR:
                pgm_info->mon_class_nr = vcpu->arch.sie_block->mcn;
                pgm_info->mon_code = vcpu->arch.sie_block->tecmc;
                break;
        case PGM_DATA:
                pgm_info->data_exc_code = vcpu->arch.sie_block->dxc;
                break;
        case PGM_PROTECTION:
                pgm_info->trans_exc_code = vcpu->arch.sie_block->tecmc;
                pgm_info->exc_access_id  = vcpu->arch.sie_block->eai;
                break;
        default:
                break;
        }

        if (vcpu->arch.sie_block->iprcc & PGM_PER) {
                pgm_info->per_code = vcpu->arch.sie_block->perc;
                pgm_info->per_atmid = vcpu->arch.sie_block->peratmid;
                pgm_info->per_address = vcpu->arch.sie_block->peraddr;
                pgm_info->per_access_id = vcpu->arch.sie_block->peraid;
        }
}

/*
 * restore ITDB to program-interruption TDB in guest lowcore
 * and set TX abort indication if required
*/
static int handle_itdb(struct kvm_vcpu *vcpu)
{
        struct kvm_s390_itdb *itdb;
        int rc;

        if (!IS_TE_ENABLED(vcpu) || !IS_ITDB_VALID(vcpu))
                return 0;
        if (current->thread.per_flags & PER_FLAG_NO_TE)
                return 0;
        itdb = (struct kvm_s390_itdb *)vcpu->arch.sie_block->itdba;
        rc = write_guest_lc(vcpu, __LC_PGM_TDB, itdb, sizeof(*itdb));
        if (rc)
                return rc;
        memset(itdb, 0, sizeof(*itdb));

        return 0;
}

#define per_event(vcpu) (vcpu->arch.sie_block->iprcc & PGM_PER)

static int handle_prog(struct kvm_vcpu *vcpu)
{
        struct kvm_s390_pgm_info pgm_info;
        psw_t psw;
        int rc;

        vcpu->stat.exit_program_interruption++;

        if (guestdbg_enabled(vcpu) && per_event(vcpu)) {
                kvm_s390_handle_per_event(vcpu);
                /* the interrupt might have been filtered out completely */
                if (vcpu->arch.sie_block->iprcc == 0)
                        return 0;
        }

        trace_kvm_s390_intercept_prog(vcpu, vcpu->arch.sie_block->iprcc);
        if (vcpu->arch.sie_block->iprcc == PGM_SPECIFICATION) {
                rc = read_guest_lc(vcpu, __LC_PGM_NEW_PSW, &psw, sizeof(psw_t));
                if (rc)
                        return rc;
                /* Avoid endless loops of specification exceptions */
                if (!is_valid_psw(&psw))
                        return -EOPNOTSUPP;
        }
        rc = handle_itdb(vcpu);
        if (rc)
                return rc;

        __extract_prog_irq(vcpu, &pgm_info);
        return kvm_s390_inject_prog_irq(vcpu, &pgm_info);
}

static int handle_instruction_and_prog(struct kvm_vcpu *vcpu)
{
        int rc, rc2;

        vcpu->stat.exit_instr_and_program++;
        rc = handle_instruction(vcpu);
        rc2 = handle_prog(vcpu);

        if (rc == -EOPNOTSUPP)
                vcpu->arch.sie_block->icptcode = 0x04;
        if (rc)
                return rc;
        return rc2;
}

/**
 * handle_external_interrupt - used for external interruption interceptions
 *
 * This interception only occurs if the CPUSTAT_EXT_INT bit was set, or if
 * the new PSW does not have external interrupts disabled. In the first case,
 * we've got to deliver the interrupt manually, and in the second case, we
 * drop to userspace to handle the situation there.
 */
static int handle_external_interrupt(struct kvm_vcpu *vcpu)
{
        u16 eic = vcpu->arch.sie_block->eic;
        struct kvm_s390_irq irq;
        psw_t newpsw;
        int rc;

        vcpu->stat.exit_external_interrupt++;

        rc = read_guest_lc(vcpu, __LC_EXT_NEW_PSW, &newpsw, sizeof(psw_t));
        if (rc)
                return rc;
        /* We can not handle clock comparator or timer interrupt with bad PSW */
        if ((eic == EXT_IRQ_CLK_COMP || eic == EXT_IRQ_CPU_TIMER) &&
            (newpsw.mask & PSW_MASK_EXT))
                return -EOPNOTSUPP;

        switch (eic) {
        case EXT_IRQ_CLK_COMP:
                irq.type = KVM_S390_INT_CLOCK_COMP;
                break;
        case EXT_IRQ_CPU_TIMER:
                irq.type = KVM_S390_INT_CPU_TIMER;
                break;
        case EXT_IRQ_EXTERNAL_CALL:
                irq.type = KVM_S390_INT_EXTERNAL_CALL;
                irq.u.extcall.code = vcpu->arch.sie_block->extcpuaddr;
                rc = kvm_s390_inject_vcpu(vcpu, &irq);
                /* ignore if another external call is already pending */
                if (rc == -EBUSY)
                        return 0;
                return rc;
        default:
                return -EOPNOTSUPP;
        }

        return kvm_s390_inject_vcpu(vcpu, &irq);
}

/**
 * Handle MOVE PAGE partial execution interception.
 *
 * This interception can only happen for guests with DAT disabled and
 * addresses that are currently not mapped in the host. Thus we try to
 * set up the mappings for the corresponding user pages here (or throw
 * addressing exceptions in case of illegal guest addresses).
 */
static int handle_mvpg_pei(struct kvm_vcpu *vcpu)
{
        unsigned long srcaddr, dstaddr;
        int reg1, reg2, rc;

        kvm_s390_get_regs_rre(vcpu, &reg1, &reg2);

        /* Make sure that the source is paged-in */
        rc = guest_translate_address(vcpu, vcpu->run->s.regs.gprs[reg2],
                                     &srcaddr, 0);
        if (rc)
                return kvm_s390_inject_prog_cond(vcpu, rc);
        rc = kvm_arch_fault_in_page(vcpu, srcaddr, 0);
        if (rc != 0)
                return rc;

        /* Make sure that the destination is paged-in */
        rc = guest_translate_address(vcpu, vcpu->run->s.regs.gprs[reg1],
                                     &dstaddr, 1);
        if (rc)
                return kvm_s390_inject_prog_cond(vcpu, rc);
        rc = kvm_arch_fault_in_page(vcpu, dstaddr, 1);
        if (rc != 0)
                return rc;

        kvm_s390_rewind_psw(vcpu, 4);

        return 0;
}

static int handle_partial_execution(struct kvm_vcpu *vcpu)
{
        if (vcpu->arch.sie_block->ipa == 0xb254)        /* MVPG */
                return handle_mvpg_pei(vcpu);
        if (vcpu->arch.sie_block->ipa >> 8 == 0xae)     /* SIGP */
                return kvm_s390_handle_sigp_pei(vcpu);

        return -EOPNOTSUPP;
}

static const intercept_handler_t intercept_funcs[] = {
        [0x00 >> 2] = handle_noop,
        [0x04 >> 2] = handle_instruction,
        [0x08 >> 2] = handle_prog,
        [0x0C >> 2] = handle_instruction_and_prog,
        [0x10 >> 2] = handle_noop,
        [0x14 >> 2] = handle_external_interrupt,
        [0x18 >> 2] = handle_noop,
        [0x1C >> 2] = kvm_s390_handle_wait,
        [0x20 >> 2] = handle_validity,
        [0x28 >> 2] = handle_stop,
        [0x38 >> 2] = handle_partial_execution,
};

int kvm_handle_sie_intercept(struct kvm_vcpu *vcpu)
{
        intercept_handler_t func;
        u8 code = vcpu->arch.sie_block->icptcode;

        if (code & 3 || (code >> 2) >= ARRAY_SIZE(intercept_funcs))
                return -EOPNOTSUPP;
        func = intercept_funcs[code >> 2];
        if (func)
                return func(vcpu);
        return -EOPNOTSUPP;
}