// SPDX-License-Identifier: GPL-2.0
/*
 * handling interprocessor communication
 *
 * Copyright IBM Corp. 2008, 2013
 *
 *    Author(s): Carsten Otte <cotte@de.ibm.com>
 *               Christian Borntraeger <borntraeger@de.ibm.com>
 *               Christian Ehrhardt <ehrhardt@de.ibm.com>
 */

#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include <linux/slab.h>
#include <asm/sigp.h>
#include "gaccess.h"
#include "kvm-s390.h"
#include "trace.h"

static int __sigp_sense(struct kvm_vcpu *vcpu, struct kvm_vcpu *dst_vcpu,
                        u64 *reg)
{
        const bool stopped = kvm_s390_test_cpuflags(dst_vcpu, CPUSTAT_STOPPED);
        int rc;
        int ext_call_pending;

        ext_call_pending = kvm_s390_ext_call_pending(dst_vcpu);
        if (!stopped && !ext_call_pending)
                rc = SIGP_CC_ORDER_CODE_ACCEPTED;
        else {
                *reg &= 0xffffffff00000000UL;
                if (ext_call_pending)
                        *reg |= SIGP_STATUS_EXT_CALL_PENDING;
                if (stopped)
                        *reg |= SIGP_STATUS_STOPPED;
                rc = SIGP_CC_STATUS_STORED;
        }

        VCPU_EVENT(vcpu, 4, "sensed status of cpu %x rc %x", dst_vcpu->vcpu_id,
                   rc);
        return rc;
}

static int __inject_sigp_emergency(struct kvm_vcpu *vcpu,
                                    struct kvm_vcpu *dst_vcpu)
{
        struct kvm_s390_irq irq = {
                .type = KVM_S390_INT_EMERGENCY,
                .u.emerg.code = vcpu->vcpu_id,
        };
        int rc = 0;

        rc = kvm_s390_inject_vcpu(dst_vcpu, &irq);
        if (!rc)
                VCPU_EVENT(vcpu, 4, "sent sigp emerg to cpu %x",
                           dst_vcpu->vcpu_id);

        return rc ? rc : SIGP_CC_ORDER_CODE_ACCEPTED;
}

static int __sigp_emergency(struct kvm_vcpu *vcpu, struct kvm_vcpu *dst_vcpu)
{
        return __inject_sigp_emergency(vcpu, dst_vcpu);
}

static int __sigp_conditional_emergency(struct kvm_vcpu *vcpu,
                                        struct kvm_vcpu *dst_vcpu,
                                        u16 asn, u64 *reg)
{
        const u64 psw_int_mask = PSW_MASK_IO | PSW_MASK_EXT;
        u16 p_asn, s_asn;
        psw_t *psw;
        bool idle;

        idle = is_vcpu_idle(vcpu);
        psw = &dst_vcpu->arch.sie_block->gpsw;
        p_asn = dst_vcpu->arch.sie_block->gcr[4] & 0xffff;  /* Primary ASN */
        s_asn = dst_vcpu->arch.sie_block->gcr[3] & 0xffff;  /* Secondary ASN */

        /* Inject the emergency signal? */
        if (!is_vcpu_stopped(vcpu)
            || (psw->mask & psw_int_mask) != psw_int_mask
            || (idle && psw->addr != 0)
            || (!idle && (asn == p_asn || asn == s_asn))) {
                return __inject_sigp_emergency(vcpu, dst_vcpu);
        } else {
                *reg &= 0xffffffff00000000UL;
                *reg |= SIGP_STATUS_INCORRECT_STATE;
                return SIGP_CC_STATUS_STORED;
        }
}

static int __sigp_external_call(struct kvm_vcpu *vcpu,
                                struct kvm_vcpu *dst_vcpu, u64 *reg)
{
        struct kvm_s390_irq irq = {
                .type = KVM_S390_INT_EXTERNAL_CALL,
                .u.extcall.code = vcpu->vcpu_id,
        };
        int rc;

        rc = kvm_s390_inject_vcpu(dst_vcpu, &irq);
        if (rc == -EBUSY) {
                *reg &= 0xffffffff00000000UL;
                *reg |= SIGP_STATUS_EXT_CALL_PENDING;
                return SIGP_CC_STATUS_STORED;
        } else if (rc == 0) {
                VCPU_EVENT(vcpu, 4, "sent sigp ext call to cpu %x",
                           dst_vcpu->vcpu_id);
        }

        return rc ? rc : SIGP_CC_ORDER_CODE_ACCEPTED;
}

static int __sigp_stop(struct kvm_vcpu *vcpu, struct kvm_vcpu *dst_vcpu)
{
        struct kvm_s390_irq irq = {
                .type = KVM_S390_SIGP_STOP,
        };
        int rc;

        rc = kvm_s390_inject_vcpu(dst_vcpu, &irq);
        if (rc == -EBUSY)
                rc = SIGP_CC_BUSY;
        else if (rc == 0)
                VCPU_EVENT(vcpu, 4, "sent sigp stop to cpu %x",
                           dst_vcpu->vcpu_id);

        return rc;
}

static int __sigp_stop_and_store_status(struct kvm_vcpu *vcpu,
                                        struct kvm_vcpu *dst_vcpu, u64 *reg)
{
        struct kvm_s390_irq irq = {
                .type = KVM_S390_SIGP_STOP,
                .u.stop.flags = KVM_S390_STOP_FLAG_STORE_STATUS,
        };
        int rc;

        rc = kvm_s390_inject_vcpu(dst_vcpu, &irq);
        if (rc == -EBUSY)
                rc = SIGP_CC_BUSY;
        else if (rc == 0)
                VCPU_EVENT(vcpu, 4, "sent sigp stop and store status to cpu %x",
                           dst_vcpu->vcpu_id);

        return rc;
}

static int __sigp_set_arch(struct kvm_vcpu *vcpu, u32 parameter,
                           u64 *status_reg)
{
        *status_reg &= 0xffffffff00000000UL;

        /* Reject set arch order, with czam we're always in z/Arch mode. */
        *status_reg |= SIGP_STATUS_INVALID_PARAMETER;
        return SIGP_CC_STATUS_STORED;
}

static int __sigp_set_prefix(struct kvm_vcpu *vcpu, struct kvm_vcpu *dst_vcpu,
                             u32 address, u64 *reg)
{
        struct kvm_s390_irq irq = {
                .type = KVM_S390_SIGP_SET_PREFIX,
                .u.prefix.address = address & 0x7fffe000u,
        };
        int rc;

        /*
         * Make sure the new value is valid memory. We only need to check the
         * first page, since address is 8k aligned and memory pieces are always
         * at least 1MB aligned and have at least a size of 1MB.
         */
        if (!kvm_is_gpa_in_memslot(vcpu->kvm, irq.u.prefix.address)) {
                *reg &= 0xffffffff00000000UL;
                *reg |= SIGP_STATUS_INVALID_PARAMETER;
                return SIGP_CC_STATUS_STORED;
        }

        rc = kvm_s390_inject_vcpu(dst_vcpu, &irq);
        if (rc == -EBUSY) {
                *reg &= 0xffffffff00000000UL;
                *reg |= SIGP_STATUS_INCORRECT_STATE;
                return SIGP_CC_STATUS_STORED;
        }

        return rc;
}

static int __sigp_store_status_at_addr(struct kvm_vcpu *vcpu,
                                       struct kvm_vcpu *dst_vcpu,
                                       u32 addr, u64 *reg)
{
        int rc;

        if (!kvm_s390_test_cpuflags(dst_vcpu, CPUSTAT_STOPPED)) {
                *reg &= 0xffffffff00000000UL;
                *reg |= SIGP_STATUS_INCORRECT_STATE;
                return SIGP_CC_STATUS_STORED;
        }

        addr &= 0x7ffffe00;
        rc = kvm_s390_store_status_unloaded(dst_vcpu, addr);
        if (rc == -EFAULT) {
                *reg &= 0xffffffff00000000UL;
                *reg |= SIGP_STATUS_INVALID_PARAMETER;
                rc = SIGP_CC_STATUS_STORED;
        }
        return rc;
}

static int __sigp_sense_running(struct kvm_vcpu *vcpu,
                                struct kvm_vcpu *dst_vcpu, u64 *reg)
{
        int rc;

        if (!test_kvm_facility(vcpu->kvm, 9)) {
                *reg &= 0xffffffff00000000UL;
                *reg |= SIGP_STATUS_INVALID_ORDER;
                return SIGP_CC_STATUS_STORED;
        }

        if (kvm_s390_test_cpuflags(dst_vcpu, CPUSTAT_RUNNING)) {
                /* running */
                rc = SIGP_CC_ORDER_CODE_ACCEPTED;
        } else {
                /* not running */
                *reg &= 0xffffffff00000000UL;
                *reg |= SIGP_STATUS_NOT_RUNNING;
                rc = SIGP_CC_STATUS_STORED;
        }

        VCPU_EVENT(vcpu, 4, "sensed running status of cpu %x rc %x",
                   dst_vcpu->vcpu_id, rc);

        return rc;
}

static int __prepare_sigp_re_start(struct kvm_vcpu *vcpu,
                                   struct kvm_vcpu *dst_vcpu, u8 order_code)
{
        struct kvm_s390_local_interrupt *li = &dst_vcpu->arch.local_int;
        /* handle (RE)START in user space */
        int rc = -EOPNOTSUPP;

        /* make sure we don't race with STOP irq injection */
        spin_lock(&li->lock);
        if (kvm_s390_is_stop_irq_pending(dst_vcpu))
                rc = SIGP_CC_BUSY;
        spin_unlock(&li->lock);

        return rc;
}

static int __prepare_sigp_cpu_reset(struct kvm_vcpu *vcpu,
                                    struct kvm_vcpu *dst_vcpu, u8 order_code)
{
        /* handle (INITIAL) CPU RESET in user space */
        return -EOPNOTSUPP;
}

static int __prepare_sigp_unknown(struct kvm_vcpu *vcpu,
                                  struct kvm_vcpu *dst_vcpu)
{
        /* handle unknown orders in user space */
        return -EOPNOTSUPP;
}

static int handle_sigp_dst(struct kvm_vcpu *vcpu, u8 order_code,
                           u16 cpu_addr, u32 parameter, u64 *status_reg)
{
        int rc;
        struct kvm_vcpu *dst_vcpu = kvm_get_vcpu_by_id(vcpu->kvm, cpu_addr);

        if (!dst_vcpu)
                return SIGP_CC_NOT_OPERATIONAL;

        /*
         * SIGP RESTART, SIGP STOP, and SIGP STOP AND STORE STATUS orders
         * are processed asynchronously. Until the affected VCPU finishes
         * its work and calls back into KVM to clear the (RESTART or STOP)
         * interrupt, we need to return any new non-reset orders "busy".
         *
         * This is important because a single VCPU could issue:
         *  1) SIGP STOP $DESTINATION
         *  2) SIGP SENSE $DESTINATION
         *
         * If the SIGP SENSE would not be rejected as "busy", it could
         * return an incorrect answer as to whether the VCPU is STOPPED
         * or OPERATING.
         */
        if (order_code != SIGP_INITIAL_CPU_RESET &&
            order_code != SIGP_CPU_RESET) {
                /*
                 * Lockless check. Both SIGP STOP and SIGP (RE)START
                 * properly synchronize everything while processing
                 * their orders, while the guest cannot observe a
                 * difference when issuing other orders from two
                 * different VCPUs.
                 */
                if (kvm_s390_is_stop_irq_pending(dst_vcpu) ||
                    kvm_s390_is_restart_irq_pending(dst_vcpu))
                        return SIGP_CC_BUSY;
        }

        switch (order_code) {
        case SIGP_SENSE:
                vcpu->stat.instruction_sigp_sense++;
                rc = __sigp_sense(vcpu, dst_vcpu, status_reg);
                break;
        case SIGP_EXTERNAL_CALL:
                vcpu->stat.instruction_sigp_external_call++;
                rc = __sigp_external_call(vcpu, dst_vcpu, status_reg);
                break;
        case SIGP_EMERGENCY_SIGNAL:
                vcpu->stat.instruction_sigp_emergency++;
                rc = __sigp_emergency(vcpu, dst_vcpu);
                break;
        case SIGP_STOP:
                vcpu->stat.instruction_sigp_stop++;
                rc = __sigp_stop(vcpu, dst_vcpu);
                break;
        case SIGP_STOP_AND_STORE_STATUS:
                vcpu->stat.instruction_sigp_stop_store_status++;
                rc = __sigp_stop_and_store_status(vcpu, dst_vcpu, status_reg);
                break;
        case SIGP_STORE_STATUS_AT_ADDRESS:
                vcpu->stat.instruction_sigp_store_status++;
                rc = __sigp_store_status_at_addr(vcpu, dst_vcpu, parameter,
                                                 status_reg);
                break;
        case SIGP_SET_PREFIX:
                vcpu->stat.instruction_sigp_prefix++;
                rc = __sigp_set_prefix(vcpu, dst_vcpu, parameter, status_reg);
                break;
        case SIGP_COND_EMERGENCY_SIGNAL:
                vcpu->stat.instruction_sigp_cond_emergency++;
                rc = __sigp_conditional_emergency(vcpu, dst_vcpu, parameter,
                                                  status_reg);
                break;
        case SIGP_SENSE_RUNNING:
                vcpu->stat.instruction_sigp_sense_running++;
                rc = __sigp_sense_running(vcpu, dst_vcpu, status_reg);
                break;
        case SIGP_START:
                vcpu->stat.instruction_sigp_start++;
                rc = __prepare_sigp_re_start(vcpu, dst_vcpu, order_code);
                break;
        case SIGP_RESTART:
                vcpu->stat.instruction_sigp_restart++;
                rc = __prepare_sigp_re_start(vcpu, dst_vcpu, order_code);
                break;
        case SIGP_INITIAL_CPU_RESET:
                vcpu->stat.instruction_sigp_init_cpu_reset++;
                rc = __prepare_sigp_cpu_reset(vcpu, dst_vcpu, order_code);
                break;
        case SIGP_CPU_RESET:
                vcpu->stat.instruction_sigp_cpu_reset++;
                rc = __prepare_sigp_cpu_reset(vcpu, dst_vcpu, order_code);
                break;
        default:
                vcpu->stat.instruction_sigp_unknown++;
                rc = __prepare_sigp_unknown(vcpu, dst_vcpu);
        }

        if (rc == -EOPNOTSUPP)
                VCPU_EVENT(vcpu, 4,
                           "sigp order %u -> cpu %x: handled in user space",
                           order_code, dst_vcpu->vcpu_id);

        return rc;
}

static int handle_sigp_order_in_user_space(struct kvm_vcpu *vcpu, u8 order_code,
                                           u16 cpu_addr)
{
        if (!vcpu->kvm->arch.user_sigp)
                return 0;

        switch (order_code) {
        case SIGP_SENSE:
        case SIGP_EXTERNAL_CALL:
        case SIGP_EMERGENCY_SIGNAL:
        case SIGP_COND_EMERGENCY_SIGNAL:
        case SIGP_SENSE_RUNNING:
                return 0;
        /* update counters as we're directly dropping to user space */
        case SIGP_STOP:
                vcpu->stat.instruction_sigp_stop++;
                break;
        case SIGP_STOP_AND_STORE_STATUS:
                vcpu->stat.instruction_sigp_stop_store_status++;
                break;
        case SIGP_STORE_STATUS_AT_ADDRESS:
                vcpu->stat.instruction_sigp_store_status++;
                break;
        case SIGP_STORE_ADDITIONAL_STATUS:
                vcpu->stat.instruction_sigp_store_adtl_status++;
                break;
        case SIGP_SET_PREFIX:
                vcpu->stat.instruction_sigp_prefix++;
                break;
        case SIGP_START:
                vcpu->stat.instruction_sigp_start++;
                break;
        case SIGP_RESTART:
                vcpu->stat.instruction_sigp_restart++;
                break;
        case SIGP_INITIAL_CPU_RESET:
                vcpu->stat.instruction_sigp_init_cpu_reset++;
                break;
        case SIGP_CPU_RESET:
                vcpu->stat.instruction_sigp_cpu_reset++;
                break;
        default:
                vcpu->stat.instruction_sigp_unknown++;
        }
        VCPU_EVENT(vcpu, 3, "SIGP: order %u for CPU %d handled in userspace",
                   order_code, cpu_addr);

        return 1;
}

int kvm_s390_handle_sigp(struct kvm_vcpu *vcpu)
{
        int r1 = (vcpu->arch.sie_block->ipa & 0x00f0) >> 4;
        int r3 = vcpu->arch.sie_block->ipa & 0x000f;
        u32 parameter;
        u16 cpu_addr = vcpu->run->s.regs.gprs[r3];
        u8 order_code;
        int rc;

        /* sigp in userspace can exit */
        if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
                return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);

        order_code = kvm_s390_get_base_disp_rs(vcpu, NULL);
        if (handle_sigp_order_in_user_space(vcpu, order_code, cpu_addr))
                return -EOPNOTSUPP;

        if (r1 % 2)
                parameter = vcpu->run->s.regs.gprs[r1];
        else
                parameter = vcpu->run->s.regs.gprs[r1 + 1];

        trace_kvm_s390_handle_sigp(vcpu, order_code, cpu_addr, parameter);
        switch (order_code) {
        case SIGP_SET_ARCHITECTURE:
                vcpu->stat.instruction_sigp_arch++;
                rc = __sigp_set_arch(vcpu, parameter,
                                     &vcpu->run->s.regs.gprs[r1]);
                break;
        default:
                rc = handle_sigp_dst(vcpu, order_code, cpu_addr,
                                     parameter,
                                     &vcpu->run->s.regs.gprs[r1]);
        }

        if (rc < 0)
                return rc;

        kvm_s390_set_psw_cc(vcpu, rc);
        return 0;
}

/*
 * Handle SIGP partial execution interception.
 *
 * This interception will occur at the source cpu when a source cpu sends an
 * external call to a target cpu and the target cpu has the WAIT bit set in
 * its cpuflags. Interception will occur after the interrupt indicator bits at
 * the target cpu have been set. All error cases will lead to instruction
 * interception, therefore nothing is to be checked or prepared.
 */
int kvm_s390_handle_sigp_pei(struct kvm_vcpu *vcpu)
{
        int r3 = vcpu->arch.sie_block->ipa & 0x000f;
        u16 cpu_addr = vcpu->run->s.regs.gprs[r3];
        struct kvm_vcpu *dest_vcpu;
        u8 order_code = kvm_s390_get_base_disp_rs(vcpu, NULL);

        if (order_code == SIGP_EXTERNAL_CALL) {
                trace_kvm_s390_handle_sigp_pei(vcpu, order_code, cpu_addr);

                dest_vcpu = kvm_get_vcpu_by_id(vcpu->kvm, cpu_addr);
                BUG_ON(dest_vcpu == NULL);

                kvm_s390_vcpu_wakeup(dest_vcpu);
                kvm_s390_set_psw_cc(vcpu, SIGP_CC_ORDER_CODE_ACCEPTED);
                return 0;
        }

        return -EOPNOTSUPP;
}