// SPDX-License-Identifier: GPL-2.0
/*
 * in-kernel handling for sie intercepts
 *
 * Copyright IBM Corp. 2008, 2020
 *
 *    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/asm-offsets.h>
#include <asm/irq.h>
#include <asm/sysinfo.h>
#include <asm/uv.h>

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

u8 kvm_s390_get_ilen(struct kvm_vcpu *vcpu)
{
        struct kvm_s390_sie_block *sie_block = vcpu->arch.sie_block;
        u8 ilen = 0;

        switch (vcpu->arch.sie_block->icptcode) {
        case ICPT_INST:
        case ICPT_INSTPROGI:
        case ICPT_OPEREXC:
        case ICPT_PARTEXEC:
        case ICPT_IOINST:
                /* instruction only stored for these icptcodes */
                ilen = insn_length(vcpu->arch.sie_block->ipa >> 8);
                /* Use the length of the EXECUTE instruction if necessary */
                if (sie_block->icptstatus & 1) {
                        ilen = (sie_block->icptstatus >> 4) & 0x6;
                        if (!ilen)
                                ilen = 4;
                }
                break;
        case ICPT_PROGI:
                /* bit 1+2 of pgmilc are the ilc, so we directly get ilen */
                ilen = vcpu->arch.sie_block->pgmilc & 0x6;
                break;
        }
        return ilen;
}

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;
        }

        /*
         * no need to check the return value of vcpu_stop as it can only have
         * an error for protvirt, but protvirt means user cpu state
         */
        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);
        KVM_EVENT(3, "validity intercept 0x%x for pid %u (kvm 0x%pK)", viwhy,
                  current->pid, vcpu->kvm);

        /* do not warn on invalid runtime instrumentation mode */
        WARN_ONCE(viwhy != 0x44, "kvm: unhandled validity intercept 0x%x\n",
                  viwhy);
        return -EINVAL;
}

static int handle_instruction(struct kvm_vcpu *vcpu)
{
        vcpu->stat.exit_instruction++;
        trace_kvm_s390_intercept_instruction(vcpu,
                                             vcpu->arch.sie_block->ipa,
                                             vcpu->arch.sie_block->ipb);

        switch (vcpu->arch.sie_block->ipa >> 8) {
        case 0x01:
                return kvm_s390_handle_01(vcpu);
        case 0x82:
                return kvm_s390_handle_lpsw(vcpu);
        case 0x83:
                return kvm_s390_handle_diag(vcpu);
        case 0xaa:
                return kvm_s390_handle_aa(vcpu);
        case 0xae:
                return kvm_s390_handle_sigp(vcpu);
        case 0xb2:
                return kvm_s390_handle_b2(vcpu);
        case 0xb6:
                return kvm_s390_handle_stctl(vcpu);
        case 0xb7:
                return kvm_s390_handle_lctl(vcpu);
        case 0xb9:
                return kvm_s390_handle_b9(vcpu);
        case 0xe3:
                return kvm_s390_handle_e3(vcpu);
        case 0xe5:
                return kvm_s390_handle_e5(vcpu);
        case 0xeb:
                return kvm_s390_handle_eb(vcpu);
        default:
                return -EOPNOTSUPP;
        }
}

static int inject_prog_on_prog_intercept(struct kvm_vcpu *vcpu)
{
        struct kvm_s390_pgm_info pgm_info = {
                .code = vcpu->arch.sie_block->iprcc,
                /* the PSW has already been rewound */
                .flags = KVM_S390_PGM_FLAGS_NO_REWIND,
        };

        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_VECTOR_PROCESSING:
        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;
        }
        return kvm_s390_inject_prog_irq(vcpu, &pgm_info);
}

/*
 * 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)
{
        psw_t psw;
        int rc;

        vcpu->stat.exit_program_interruption++;

        /*
         * Intercept 8 indicates a loop of specification exceptions
         * for protected guests.
         */
        if (kvm_s390_pv_cpu_is_protected(vcpu))
                return -EOPNOTSUPP;

        if (guestdbg_enabled(vcpu) && per_event(vcpu)) {
                rc = kvm_s390_handle_per_event(vcpu);
                if (rc)
                        return rc;
                /* 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;

        return inject_prog_on_prog_intercept(vcpu);
}

/**
 * handle_external_interrupt - used for external interruption interceptions
 * @vcpu: virtual cpu
 *
 * 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_mvpg_pei - Handle MOVE PAGE partial execution interception.
 * @vcpu: virtual cpu
 *
 * 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],
                                     reg2, &srcaddr, GACC_FETCH);
        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],
                                     reg1, &dstaddr, GACC_STORE);
        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_retry_instr(vcpu);

        return 0;
}

static int handle_partial_execution(struct kvm_vcpu *vcpu)
{
        vcpu->stat.exit_pei++;

        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;
}

/*
 * Handle the sthyi instruction that provides the guest with system
 * information, like current CPU resources available at each level of
 * the machine.
 */
int handle_sthyi(struct kvm_vcpu *vcpu)
{
        int reg1, reg2, r = 0;
        u64 code, addr, cc = 0, rc = 0;
        struct sthyi_sctns *sctns = NULL;

        if (!test_kvm_facility(vcpu->kvm, 74))
                return kvm_s390_inject_program_int(vcpu, PGM_OPERATION);

        kvm_s390_get_regs_rre(vcpu, &reg1, &reg2);
        code = vcpu->run->s.regs.gprs[reg1];
        addr = vcpu->run->s.regs.gprs[reg2];

        vcpu->stat.instruction_sthyi++;
        VCPU_EVENT(vcpu, 3, "STHYI: fc: %llu addr: 0x%016llx", code, addr);
        trace_kvm_s390_handle_sthyi(vcpu, code, addr);

        if (reg1 == reg2 || reg1 & 1 || reg2 & 1)
                return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);

        if (code & 0xffff) {
                cc = 3;
                rc = 4;
                goto out;
        }

        if (!kvm_s390_pv_cpu_is_protected(vcpu) && (addr & ~PAGE_MASK))
                return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);

        sctns = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT);
        if (!sctns)
                return -ENOMEM;

        cc = sthyi_fill(sctns, &rc);

out:
        if (!cc) {
                if (kvm_s390_pv_cpu_is_protected(vcpu)) {
                        memcpy((void *)(sida_origin(vcpu->arch.sie_block)),
                               sctns, PAGE_SIZE);
                } else {
                        r = write_guest(vcpu, addr, reg2, sctns, PAGE_SIZE);
                        if (r) {
                                free_page((unsigned long)sctns);
                                return kvm_s390_inject_prog_cond(vcpu, r);
                        }
                }
        }

        free_page((unsigned long)sctns);
        vcpu->run->s.regs.gprs[reg2 + 1] = rc;
        kvm_s390_set_psw_cc(vcpu, cc);
        return r;
}

static int handle_operexc(struct kvm_vcpu *vcpu)
{
        psw_t oldpsw, newpsw;
        int rc;

        vcpu->stat.exit_operation_exception++;
        trace_kvm_s390_handle_operexc(vcpu, vcpu->arch.sie_block->ipa,
                                      vcpu->arch.sie_block->ipb);

        if (vcpu->arch.sie_block->ipa == 0xb256)
                return handle_sthyi(vcpu);

        if (vcpu->arch.sie_block->ipa == 0 && vcpu->kvm->arch.user_instr0)
                return -EOPNOTSUPP;
        rc = read_guest_lc(vcpu, __LC_PGM_NEW_PSW, &newpsw, sizeof(psw_t));
        if (rc)
                return rc;
        /*
         * Avoid endless loops of operation exceptions, if the pgm new
         * PSW will cause a new operation exception.
         * The heuristic checks if the pgm new psw is within 6 bytes before
         * the faulting psw address (with same DAT, AS settings) and the
         * new psw is not a wait psw and the fault was not triggered by
         * problem state.
         */
        oldpsw = vcpu->arch.sie_block->gpsw;
        if (oldpsw.addr - newpsw.addr <= 6 &&
            !(newpsw.mask & PSW_MASK_WAIT) &&
            !(oldpsw.mask & PSW_MASK_PSTATE) &&
            (newpsw.mask & PSW_MASK_ASC) == (oldpsw.mask & PSW_MASK_ASC) &&
            (newpsw.mask & PSW_MASK_DAT) == (oldpsw.mask & PSW_MASK_DAT))
                return -EOPNOTSUPP;

        return kvm_s390_inject_program_int(vcpu, PGM_OPERATION);
}

static int handle_pv_spx(struct kvm_vcpu *vcpu)
{
        u32 pref = *(u32 *)vcpu->arch.sie_block->sidad;

        kvm_s390_set_prefix(vcpu, pref);
        trace_kvm_s390_handle_prefix(vcpu, 1, pref);
        return 0;
}

static int handle_pv_sclp(struct kvm_vcpu *vcpu)
{
        struct kvm_s390_float_interrupt *fi = &vcpu->kvm->arch.float_int;

        spin_lock(&fi->lock);
        /*
         * 2 cases:
         * a: an sccb answering interrupt was already pending or in flight.
         *    As the sccb value is not known we can simply set some value to
         *    trigger delivery of a saved SCCB. UV will then use its saved
         *    copy of the SCCB value.
         * b: an error SCCB interrupt needs to be injected so we also inject
         *    a fake SCCB address. Firmware will use the proper one.
         * This makes sure, that both errors and real sccb returns will only
         * be delivered after a notification intercept (instruction has
         * finished) but not after others.
         */
        fi->srv_signal.ext_params |= 0x43000;
        set_bit(IRQ_PEND_EXT_SERVICE, &fi->pending_irqs);
        clear_bit(IRQ_PEND_EXT_SERVICE, &fi->masked_irqs);
        spin_unlock(&fi->lock);
        return 0;
}

static int handle_pv_uvc(struct kvm_vcpu *vcpu)
{
        struct uv_cb_share *guest_uvcb = (void *)vcpu->arch.sie_block->sidad;
        struct uv_cb_cts uvcb = {
                .header.cmd     = UVC_CMD_UNPIN_PAGE_SHARED,
                .header.len     = sizeof(uvcb),
                .guest_handle   = kvm_s390_pv_get_handle(vcpu->kvm),
                .gaddr          = guest_uvcb->paddr,
        };
        int rc;

        if (guest_uvcb->header.cmd != UVC_CMD_REMOVE_SHARED_ACCESS) {
                WARN_ONCE(1, "Unexpected notification intercept for UVC 0x%x\n",
                          guest_uvcb->header.cmd);
                return 0;
        }
        rc = gmap_make_secure(vcpu->arch.gmap, uvcb.gaddr, &uvcb);
        /*
         * If the unpin did not succeed, the guest will exit again for the UVC
         * and we will retry the unpin.
         */
        if (rc == -EINVAL)
                return 0;
        return rc;
}

static int handle_pv_notification(struct kvm_vcpu *vcpu)
{
        if (vcpu->arch.sie_block->ipa == 0xb210)
                return handle_pv_spx(vcpu);
        if (vcpu->arch.sie_block->ipa == 0xb220)
                return handle_pv_sclp(vcpu);
        if (vcpu->arch.sie_block->ipa == 0xb9a4)
                return handle_pv_uvc(vcpu);

        return handle_instruction(vcpu);
}

int kvm_handle_sie_intercept(struct kvm_vcpu *vcpu)
{
        int rc, per_rc = 0;

        if (kvm_is_ucontrol(vcpu->kvm))
                return -EOPNOTSUPP;

        switch (vcpu->arch.sie_block->icptcode) {
        case ICPT_EXTREQ:
                vcpu->stat.exit_external_request++;
                return 0;
        case ICPT_IOREQ:
                vcpu->stat.exit_io_request++;
                return 0;
        case ICPT_INST:
                rc = handle_instruction(vcpu);
                break;
        case ICPT_PROGI:
                return handle_prog(vcpu);
        case ICPT_EXTINT:
                return handle_external_interrupt(vcpu);
        case ICPT_WAIT:
                return kvm_s390_handle_wait(vcpu);
        case ICPT_VALIDITY:
                return handle_validity(vcpu);
        case ICPT_STOP:
                return handle_stop(vcpu);
        case ICPT_OPEREXC:
                rc = handle_operexc(vcpu);
                break;
        case ICPT_PARTEXEC:
                rc = handle_partial_execution(vcpu);
                break;
        case ICPT_KSS:
                rc = kvm_s390_skey_check_enable(vcpu);
                break;
        case ICPT_MCHKREQ:
        case ICPT_INT_ENABLE:
                /*
                 * PSW bit 13 or a CR (0, 6, 14) changed and we might
                 * now be able to deliver interrupts. The pre-run code
                 * will take care of this.
                 */
                rc = 0;
                break;
        case ICPT_PV_INSTR:
                rc = handle_instruction(vcpu);
                break;
        case ICPT_PV_NOTIFY:
                rc = handle_pv_notification(vcpu);
                break;
        case ICPT_PV_PREF:
                rc = 0;
                gmap_convert_to_secure(vcpu->arch.gmap,
                                       kvm_s390_get_prefix(vcpu));
                gmap_convert_to_secure(vcpu->arch.gmap,
                                       kvm_s390_get_prefix(vcpu) + PAGE_SIZE);
                break;
        default:
                return -EOPNOTSUPP;
        }

        /* process PER, also if the instrution is processed in user space */
        if (vcpu->arch.sie_block->icptstatus & 0x02 &&
            (!rc || rc == -EOPNOTSUPP))
                per_rc = kvm_s390_handle_per_ifetch_icpt(vcpu);
        return per_rc ? per_rc : rc;
}