// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright 2012 Michael Ellerman, IBM Corporation.
 * Copyright 2012 Benjamin Herrenschmidt, IBM Corporation.
 */

#include <linux/kernel.h>
#include <linux/kvm_host.h>
#include <linux/err.h>
#include <linux/gfp.h>
#include <linux/anon_inodes.h>
#include <linux/spinlock.h>
#include <linux/debugfs.h>
#include <linux/uaccess.h>

#include <asm/kvm_book3s.h>
#include <asm/kvm_ppc.h>
#include <asm/hvcall.h>
#include <asm/xics.h>
#include <asm/time.h>

#include <linux/seq_file.h>

#include "book3s_xics.h"

#if 1
#define XICS_DBG(fmt...) do { } while (0)
#else
#define XICS_DBG(fmt...) trace_printk(fmt)
#endif

#define ENABLE_REALMODE true
#define DEBUG_REALMODE  false

/*
 * LOCKING
 * =======
 *
 * Each ICS has a spin lock protecting the information about the IRQ
 * sources and avoiding simultaneous deliveries of the same interrupt.
 *
 * ICP operations are done via a single compare & swap transaction
 * (most ICP state fits in the union kvmppc_icp_state)
 */

/*
 * TODO
 * ====
 *
 * - To speed up resends, keep a bitmap of "resend" set bits in the
 *   ICS
 *
 * - Speed up server# -> ICP lookup (array ? hash table ?)
 *
 * - Make ICS lockless as well, or at least a per-interrupt lock or hashed
 *   locks array to improve scalability
 */

/* -- ICS routines -- */

static void icp_deliver_irq(struct kvmppc_xics *xics, struct kvmppc_icp *icp,
                            u32 new_irq, bool check_resend);

/*
 * Return value ideally indicates how the interrupt was handled, but no
 * callers look at it (given that we don't implement KVM_IRQ_LINE_STATUS),
 * so just return 0.
 */
static int ics_deliver_irq(struct kvmppc_xics *xics, u32 irq, u32 level)
{
        struct ics_irq_state *state;
        struct kvmppc_ics *ics;
        u16 src;
        u32 pq_old, pq_new;

        XICS_DBG("ics deliver %#x (level: %d)\n", irq, level);

        ics = kvmppc_xics_find_ics(xics, irq, &src);
        if (!ics) {
                XICS_DBG("ics_deliver_irq: IRQ 0x%06x not found !\n", irq);
                return -EINVAL;
        }
        state = &ics->irq_state[src];
        if (!state->exists)
                return -EINVAL;

        if (level == KVM_INTERRUPT_SET_LEVEL || level == KVM_INTERRUPT_SET)
                level = 1;
        else if (level == KVM_INTERRUPT_UNSET)
                level = 0;
        /*
         * Take other values the same as 1, consistent with original code.
         * maybe WARN here?
         */

        if (!state->lsi && level == 0) /* noop for MSI */
                return 0;

        do {
                pq_old = state->pq_state;
                if (state->lsi) {
                        if (level) {
                                if (pq_old & PQ_PRESENTED)
                                        /* Setting already set LSI ... */
                                        return 0;

                                pq_new = PQ_PRESENTED;
                        } else
                                pq_new = 0;
                } else
                        pq_new = ((pq_old << 1) & 3) | PQ_PRESENTED;
        } while (cmpxchg(&state->pq_state, pq_old, pq_new) != pq_old);

        /* Test P=1, Q=0, this is the only case where we present */
        if (pq_new == PQ_PRESENTED)
                icp_deliver_irq(xics, NULL, irq, false);

        /* Record which CPU this arrived on for passed-through interrupts */
        if (state->host_irq)
                state->intr_cpu = raw_smp_processor_id();

        return 0;
}

static void ics_check_resend(struct kvmppc_xics *xics, struct kvmppc_ics *ics,
                             struct kvmppc_icp *icp)
{
        int i;

        for (i = 0; i < KVMPPC_XICS_IRQ_PER_ICS; i++) {
                struct ics_irq_state *state = &ics->irq_state[i];
                if (state->resend) {
                        XICS_DBG("resend %#x prio %#x\n", state->number,
                                      state->priority);
                        icp_deliver_irq(xics, icp, state->number, true);
                }
        }
}

static bool write_xive(struct kvmppc_xics *xics, struct kvmppc_ics *ics,
                       struct ics_irq_state *state,
                       u32 server, u32 priority, u32 saved_priority)
{
        bool deliver;
        unsigned long flags;

        local_irq_save(flags);
        arch_spin_lock(&ics->lock);

        state->server = server;
        state->priority = priority;
        state->saved_priority = saved_priority;
        deliver = false;
        if ((state->masked_pending || state->resend) && priority != MASKED) {
                state->masked_pending = 0;
                state->resend = 0;
                deliver = true;
        }

        arch_spin_unlock(&ics->lock);
        local_irq_restore(flags);

        return deliver;
}

int kvmppc_xics_set_xive(struct kvm *kvm, u32 irq, u32 server, u32 priority)
{
        struct kvmppc_xics *xics = kvm->arch.xics;
        struct kvmppc_icp *icp;
        struct kvmppc_ics *ics;
        struct ics_irq_state *state;
        u16 src;

        if (!xics)
                return -ENODEV;

        ics = kvmppc_xics_find_ics(xics, irq, &src);
        if (!ics)
                return -EINVAL;
        state = &ics->irq_state[src];

        icp = kvmppc_xics_find_server(kvm, server);
        if (!icp)
                return -EINVAL;

        XICS_DBG("set_xive %#x server %#x prio %#x MP:%d RS:%d\n",
                 irq, server, priority,
                 state->masked_pending, state->resend);

        if (write_xive(xics, ics, state, server, priority, priority))
                icp_deliver_irq(xics, icp, irq, false);

        return 0;
}

int kvmppc_xics_get_xive(struct kvm *kvm, u32 irq, u32 *server, u32 *priority)
{
        struct kvmppc_xics *xics = kvm->arch.xics;
        struct kvmppc_ics *ics;
        struct ics_irq_state *state;
        u16 src;
        unsigned long flags;

        if (!xics)
                return -ENODEV;

        ics = kvmppc_xics_find_ics(xics, irq, &src);
        if (!ics)
                return -EINVAL;
        state = &ics->irq_state[src];

        local_irq_save(flags);
        arch_spin_lock(&ics->lock);
        *server = state->server;
        *priority = state->priority;
        arch_spin_unlock(&ics->lock);
        local_irq_restore(flags);

        return 0;
}

int kvmppc_xics_int_on(struct kvm *kvm, u32 irq)
{
        struct kvmppc_xics *xics = kvm->arch.xics;
        struct kvmppc_icp *icp;
        struct kvmppc_ics *ics;
        struct ics_irq_state *state;
        u16 src;

        if (!xics)
                return -ENODEV;

        ics = kvmppc_xics_find_ics(xics, irq, &src);
        if (!ics)
                return -EINVAL;
        state = &ics->irq_state[src];

        icp = kvmppc_xics_find_server(kvm, state->server);
        if (!icp)
                return -EINVAL;

        if (write_xive(xics, ics, state, state->server, state->saved_priority,
                       state->saved_priority))
                icp_deliver_irq(xics, icp, irq, false);

        return 0;
}

int kvmppc_xics_int_off(struct kvm *kvm, u32 irq)
{
        struct kvmppc_xics *xics = kvm->arch.xics;
        struct kvmppc_ics *ics;
        struct ics_irq_state *state;
        u16 src;

        if (!xics)
                return -ENODEV;

        ics = kvmppc_xics_find_ics(xics, irq, &src);
        if (!ics)
                return -EINVAL;
        state = &ics->irq_state[src];

        write_xive(xics, ics, state, state->server, MASKED, state->priority);

        return 0;
}

/* -- ICP routines, including hcalls -- */

static inline bool icp_try_update(struct kvmppc_icp *icp,
                                  union kvmppc_icp_state old,
                                  union kvmppc_icp_state new,
                                  bool change_self)
{
        bool success;

        /* Calculate new output value */
        new.out_ee = (new.xisr && (new.pending_pri < new.cppr));

        /* Attempt atomic update */
        success = cmpxchg64(&icp->state.raw, old.raw, new.raw) == old.raw;
        if (!success)
                goto bail;

        XICS_DBG("UPD [%04lx] - C:%02x M:%02x PP: %02x PI:%06x R:%d O:%d\n",
                 icp->server_num,
                 old.cppr, old.mfrr, old.pending_pri, old.xisr,
                 old.need_resend, old.out_ee);
        XICS_DBG("UPD        - C:%02x M:%02x PP: %02x PI:%06x R:%d O:%d\n",
                 new.cppr, new.mfrr, new.pending_pri, new.xisr,
                 new.need_resend, new.out_ee);
        /*
         * Check for output state update
         *
         * Note that this is racy since another processor could be updating
         * the state already. This is why we never clear the interrupt output
         * here, we only ever set it. The clear only happens prior to doing
         * an update and only by the processor itself. Currently we do it
         * in Accept (H_XIRR) and Up_Cppr (H_XPPR).
         *
         * We also do not try to figure out whether the EE state has changed,
         * we unconditionally set it if the new state calls for it. The reason
         * for that is that we opportunistically remove the pending interrupt
         * flag when raising CPPR, so we need to set it back here if an
         * interrupt is still pending.
         */
        if (new.out_ee) {
                kvmppc_book3s_queue_irqprio(icp->vcpu,
                                            BOOK3S_INTERRUPT_EXTERNAL);
                if (!change_self)
                        kvmppc_fast_vcpu_kick(icp->vcpu);
        }
 bail:
        return success;
}

static void icp_check_resend(struct kvmppc_xics *xics,
                             struct kvmppc_icp *icp)
{
        u32 icsid;

        /* Order this load with the test for need_resend in the caller */
        smp_rmb();
        for_each_set_bit(icsid, icp->resend_map, xics->max_icsid + 1) {
                struct kvmppc_ics *ics = xics->ics[icsid];

                if (!test_and_clear_bit(icsid, icp->resend_map))
                        continue;
                if (!ics)
                        continue;
                ics_check_resend(xics, ics, icp);
        }
}

static bool icp_try_to_deliver(struct kvmppc_icp *icp, u32 irq, u8 priority,
                               u32 *reject)
{
        union kvmppc_icp_state old_state, new_state;
        bool success;

        XICS_DBG("try deliver %#x(P:%#x) to server %#lx\n", irq, priority,
                 icp->server_num);

        do {
                old_state = new_state = READ_ONCE(icp->state);

                *reject = 0;

                /* See if we can deliver */
                success = new_state.cppr > priority &&
                        new_state.mfrr > priority &&
                        new_state.pending_pri > priority;

                /*
                 * If we can, check for a rejection and perform the
                 * delivery
                 */
                if (success) {
                        *reject = new_state.xisr;
                        new_state.xisr = irq;
                        new_state.pending_pri = priority;
                } else {
                        /*
                         * If we failed to deliver we set need_resend
                         * so a subsequent CPPR state change causes us
                         * to try a new delivery.
                         */
                        new_state.need_resend = true;
                }

        } while (!icp_try_update(icp, old_state, new_state, false));

        return success;
}

static void icp_deliver_irq(struct kvmppc_xics *xics, struct kvmppc_icp *icp,
                            u32 new_irq, bool check_resend)
{
        struct ics_irq_state *state;
        struct kvmppc_ics *ics;
        u32 reject;
        u16 src;
        unsigned long flags;

        /*
         * This is used both for initial delivery of an interrupt and
         * for subsequent rejection.
         *
         * Rejection can be racy vs. resends. We have evaluated the
         * rejection in an atomic ICP transaction which is now complete,
         * so potentially the ICP can already accept the interrupt again.
         *
         * So we need to retry the delivery. Essentially the reject path
         * boils down to a failed delivery. Always.
         *
         * Now the interrupt could also have moved to a different target,
         * thus we may need to re-do the ICP lookup as well
         */

 again:
        /* Get the ICS state and lock it */
        ics = kvmppc_xics_find_ics(xics, new_irq, &src);
        if (!ics) {
                XICS_DBG("icp_deliver_irq: IRQ 0x%06x not found !\n", new_irq);
                return;
        }
        state = &ics->irq_state[src];

        /* Get a lock on the ICS */
        local_irq_save(flags);
        arch_spin_lock(&ics->lock);

        /* Get our server */
        if (!icp || state->server != icp->server_num) {
                icp = kvmppc_xics_find_server(xics->kvm, state->server);
                if (!icp) {
                        pr_warn("icp_deliver_irq: IRQ 0x%06x server 0x%x not found !\n",
                                new_irq, state->server);
                        goto out;
                }
        }

        if (check_resend)
                if (!state->resend)
                        goto out;

        /* Clear the resend bit of that interrupt */
        state->resend = 0;

        /*
         * If masked, bail out
         *
         * Note: PAPR doesn't mention anything about masked pending
         * when doing a resend, only when doing a delivery.
         *
         * However that would have the effect of losing a masked
         * interrupt that was rejected and isn't consistent with
         * the whole masked_pending business which is about not
         * losing interrupts that occur while masked.
         *
         * I don't differentiate normal deliveries and resends, this
         * implementation will differ from PAPR and not lose such
         * interrupts.
         */
        if (state->priority == MASKED) {
                XICS_DBG("irq %#x masked pending\n", new_irq);
                state->masked_pending = 1;
                goto out;
        }

        /*
         * Try the delivery, this will set the need_resend flag
         * in the ICP as part of the atomic transaction if the
         * delivery is not possible.
         *
         * Note that if successful, the new delivery might have itself
         * rejected an interrupt that was "delivered" before we took the
         * ics spin lock.
         *
         * In this case we do the whole sequence all over again for the
         * new guy. We cannot assume that the rejected interrupt is less
         * favored than the new one, and thus doesn't need to be delivered,
         * because by the time we exit icp_try_to_deliver() the target
         * processor may well have already consumed & completed it, and thus
         * the rejected interrupt might actually be already acceptable.
         */
        if (icp_try_to_deliver(icp, new_irq, state->priority, &reject)) {
                /*
                 * Delivery was successful, did we reject somebody else ?
                 */
                if (reject && reject != XICS_IPI) {
                        arch_spin_unlock(&ics->lock);
                        local_irq_restore(flags);
                        new_irq = reject;
                        check_resend = false;
                        goto again;
                }
        } else {
                /*
                 * We failed to deliver the interrupt we need to set the
                 * resend map bit and mark the ICS state as needing a resend
                 */
                state->resend = 1;

                /*
                 * Make sure when checking resend, we don't miss the resend
                 * if resend_map bit is seen and cleared.
                 */
                smp_wmb();
                set_bit(ics->icsid, icp->resend_map);

                /*
                 * If the need_resend flag got cleared in the ICP some time
                 * between icp_try_to_deliver() atomic update and now, then
                 * we know it might have missed the resend_map bit. So we
                 * retry
                 */
                smp_mb();
                if (!icp->state.need_resend) {
                        state->resend = 0;
                        arch_spin_unlock(&ics->lock);
                        local_irq_restore(flags);
                        check_resend = false;
                        goto again;
                }
        }
 out:
        arch_spin_unlock(&ics->lock);
        local_irq_restore(flags);
}

static void icp_down_cppr(struct kvmppc_xics *xics, struct kvmppc_icp *icp,
                          u8 new_cppr)
{
        union kvmppc_icp_state old_state, new_state;
        bool resend;

        /*
         * This handles several related states in one operation:
         *
         * ICP State: Down_CPPR
         *
         * Load CPPR with new value and if the XISR is 0
         * then check for resends:
         *
         * ICP State: Resend
         *
         * If MFRR is more favored than CPPR, check for IPIs
         * and notify ICS of a potential resend. This is done
         * asynchronously (when used in real mode, we will have
         * to exit here).
         *
         * We do not handle the complete Check_IPI as documented
         * here. In the PAPR, this state will be used for both
         * Set_MFRR and Down_CPPR. However, we know that we aren't
         * changing the MFRR state here so we don't need to handle
         * the case of an MFRR causing a reject of a pending irq,
         * this will have been handled when the MFRR was set in the
         * first place.
         *
         * Thus we don't have to handle rejects, only resends.
         *
         * When implementing real mode for HV KVM, resend will lead to
         * a H_TOO_HARD return and the whole transaction will be handled
         * in virtual mode.
         */
        do {
                old_state = new_state = READ_ONCE(icp->state);

                /* Down_CPPR */
                new_state.cppr = new_cppr;

                /*
                 * Cut down Resend / Check_IPI / IPI
                 *
                 * The logic is that we cannot have a pending interrupt
                 * trumped by an IPI at this point (see above), so we
                 * know that either the pending interrupt is already an
                 * IPI (in which case we don't care to override it) or
                 * it's either more favored than us or non existent
                 */
                if (new_state.mfrr < new_cppr &&
                    new_state.mfrr <= new_state.pending_pri) {
                        WARN_ON(new_state.xisr != XICS_IPI &&
                                new_state.xisr != 0);
                        new_state.pending_pri = new_state.mfrr;
                        new_state.xisr = XICS_IPI;
                }

                /* Latch/clear resend bit */
                resend = new_state.need_resend;
                new_state.need_resend = 0;

        } while (!icp_try_update(icp, old_state, new_state, true));

        /*
         * Now handle resend checks. Those are asynchronous to the ICP
         * state update in HW (ie bus transactions) so we can handle them
         * separately here too
         */
        if (resend)
                icp_check_resend(xics, icp);
}

static noinline unsigned long kvmppc_h_xirr(struct kvm_vcpu *vcpu)
{
        union kvmppc_icp_state old_state, new_state;
        struct kvmppc_icp *icp = vcpu->arch.icp;
        u32 xirr;

        /* First, remove EE from the processor */
        kvmppc_book3s_dequeue_irqprio(icp->vcpu, BOOK3S_INTERRUPT_EXTERNAL);

        /*
         * ICP State: Accept_Interrupt
         *
         * Return the pending interrupt (if any) along with the
         * current CPPR, then clear the XISR & set CPPR to the
         * pending priority
         */
        do {
                old_state = new_state = READ_ONCE(icp->state);

                xirr = old_state.xisr | (((u32)old_state.cppr) << 24);
                if (!old_state.xisr)
                        break;
                new_state.cppr = new_state.pending_pri;
                new_state.pending_pri = 0xff;
                new_state.xisr = 0;

        } while (!icp_try_update(icp, old_state, new_state, true));

        XICS_DBG("h_xirr vcpu %d xirr %#x\n", vcpu->vcpu_id, xirr);

        return xirr;
}

static noinline int kvmppc_h_ipi(struct kvm_vcpu *vcpu, unsigned long server,
                                 unsigned long mfrr)
{
        union kvmppc_icp_state old_state, new_state;
        struct kvmppc_xics *xics = vcpu->kvm->arch.xics;
        struct kvmppc_icp *icp;
        u32 reject;
        bool resend;
        bool local;

        XICS_DBG("h_ipi vcpu %d to server %lu mfrr %#lx\n",
                 vcpu->vcpu_id, server, mfrr);

        icp = vcpu->arch.icp;
        local = icp->server_num == server;
        if (!local) {
                icp = kvmppc_xics_find_server(vcpu->kvm, server);
                if (!icp)
                        return H_PARAMETER;
        }

        /*
         * ICP state: Set_MFRR
         *
         * If the CPPR is more favored than the new MFRR, then
         * nothing needs to be rejected as there can be no XISR to
         * reject.  If the MFRR is being made less favored then
         * there might be a previously-rejected interrupt needing
         * to be resent.
         *
         * ICP state: Check_IPI
         *
         * If the CPPR is less favored, then we might be replacing
         * an interrupt, and thus need to possibly reject it.
         *
         * ICP State: IPI
         *
         * Besides rejecting any pending interrupts, we also
         * update XISR and pending_pri to mark IPI as pending.
         *
         * PAPR does not describe this state, but if the MFRR is being
         * made less favored than its earlier value, there might be
         * a previously-rejected interrupt needing to be resent.
         * Ideally, we would want to resend only if
         *      prio(pending_interrupt) < mfrr &&
         *      prio(pending_interrupt) < cppr
         * where pending interrupt is the one that was rejected. But
         * we don't have that state, so we simply trigger a resend
         * whenever the MFRR is made less favored.
         */
        do {
                old_state = new_state = READ_ONCE(icp->state);

                /* Set_MFRR */
                new_state.mfrr = mfrr;

                /* Check_IPI */
                reject = 0;
                resend = false;
                if (mfrr < new_state.cppr) {
                        /* Reject a pending interrupt if not an IPI */
                        if (mfrr <= new_state.pending_pri) {
                                reject = new_state.xisr;
                                new_state.pending_pri = mfrr;
                                new_state.xisr = XICS_IPI;
                        }
                }

                if (mfrr > old_state.mfrr) {
                        resend = new_state.need_resend;
                        new_state.need_resend = 0;
                }
        } while (!icp_try_update(icp, old_state, new_state, local));

        /* Handle reject */
        if (reject && reject != XICS_IPI)
                icp_deliver_irq(xics, icp, reject, false);

        /* Handle resend */
        if (resend)
                icp_check_resend(xics, icp);

        return H_SUCCESS;
}

static int kvmppc_h_ipoll(struct kvm_vcpu *vcpu, unsigned long server)
{
        union kvmppc_icp_state state;
        struct kvmppc_icp *icp;

        icp = vcpu->arch.icp;
        if (icp->server_num != server) {
                icp = kvmppc_xics_find_server(vcpu->kvm, server);
                if (!icp)
                        return H_PARAMETER;
        }
        state = READ_ONCE(icp->state);
        kvmppc_set_gpr(vcpu, 4, ((u32)state.cppr << 24) | state.xisr);
        kvmppc_set_gpr(vcpu, 5, state.mfrr);
        return H_SUCCESS;
}

static noinline void kvmppc_h_cppr(struct kvm_vcpu *vcpu, unsigned long cppr)
{
        union kvmppc_icp_state old_state, new_state;
        struct kvmppc_xics *xics = vcpu->kvm->arch.xics;
        struct kvmppc_icp *icp = vcpu->arch.icp;
        u32 reject;

        XICS_DBG("h_cppr vcpu %d cppr %#lx\n", vcpu->vcpu_id, cppr);

        /*
         * ICP State: Set_CPPR
         *
         * We can safely compare the new value with the current
         * value outside of the transaction as the CPPR is only
         * ever changed by the processor on itself
         */
        if (cppr > icp->state.cppr)
                icp_down_cppr(xics, icp, cppr);
        else if (cppr == icp->state.cppr)
                return;

        /*
         * ICP State: Up_CPPR
         *
         * The processor is raising its priority, this can result
         * in a rejection of a pending interrupt:
         *
         * ICP State: Reject_Current
         *
         * We can remove EE from the current processor, the update
         * transaction will set it again if needed
         */
        kvmppc_book3s_dequeue_irqprio(icp->vcpu, BOOK3S_INTERRUPT_EXTERNAL);

        do {
                old_state = new_state = READ_ONCE(icp->state);

                reject = 0;
                new_state.cppr = cppr;

                if (cppr <= new_state.pending_pri) {
                        reject = new_state.xisr;
                        new_state.xisr = 0;
                        new_state.pending_pri = 0xff;
                }

        } while (!icp_try_update(icp, old_state, new_state, true));

        /*
         * Check for rejects. They are handled by doing a new delivery
         * attempt (see comments in icp_deliver_irq).
         */
        if (reject && reject != XICS_IPI)
                icp_deliver_irq(xics, icp, reject, false);
}

static int ics_eoi(struct kvm_vcpu *vcpu, u32 irq)
{
        struct kvmppc_xics *xics = vcpu->kvm->arch.xics;
        struct kvmppc_icp *icp = vcpu->arch.icp;
        struct kvmppc_ics *ics;
        struct ics_irq_state *state;
        u16 src;
        u32 pq_old, pq_new;

        /*
         * ICS EOI handling: For LSI, if P bit is still set, we need to
         * resend it.
         *
         * For MSI, we move Q bit into P (and clear Q). If it is set,
         * resend it.
         */

        ics = kvmppc_xics_find_ics(xics, irq, &src);
        if (!ics) {
                XICS_DBG("ios_eoi: IRQ 0x%06x not found !\n", irq);
                return H_PARAMETER;
        }
        state = &ics->irq_state[src];

        if (state->lsi)
                pq_new = state->pq_state;
        else
                do {
                        pq_old = state->pq_state;
                        pq_new = pq_old >> 1;
                } while (cmpxchg(&state->pq_state, pq_old, pq_new) != pq_old);

        if (pq_new & PQ_PRESENTED)
                icp_deliver_irq(xics, icp, irq, false);

        kvm_notify_acked_irq(vcpu->kvm, 0, irq);

        return H_SUCCESS;
}

static noinline int kvmppc_h_eoi(struct kvm_vcpu *vcpu, unsigned long xirr)
{
        struct kvmppc_xics *xics = vcpu->kvm->arch.xics;
        struct kvmppc_icp *icp = vcpu->arch.icp;
        u32 irq = xirr & 0x00ffffff;

        XICS_DBG("h_eoi vcpu %d eoi %#lx\n", vcpu->vcpu_id, xirr);

        /*
         * ICP State: EOI
         *
         * Note: If EOI is incorrectly used by SW to lower the CPPR
         * value (ie more favored), we do not check for rejection of
         * a pending interrupt, this is a SW error and PAPR specifies
         * that we don't have to deal with it.
         *
         * The sending of an EOI to the ICS is handled after the
         * CPPR update
         *
         * ICP State: Down_CPPR which we handle
         * in a separate function as it's shared with H_CPPR.
         */
        icp_down_cppr(xics, icp, xirr >> 24);

        /* IPIs have no EOI */
        if (irq == XICS_IPI)
                return H_SUCCESS;

        return ics_eoi(vcpu, irq);
}

int kvmppc_xics_rm_complete(struct kvm_vcpu *vcpu, u32 hcall)
{
        struct kvmppc_xics *xics = vcpu->kvm->arch.xics;
        struct kvmppc_icp *icp = vcpu->arch.icp;

        XICS_DBG("XICS_RM: H_%x completing, act: %x state: %lx tgt: %p\n",
                 hcall, icp->rm_action, icp->rm_dbgstate.raw, icp->rm_dbgtgt);

        if (icp->rm_action & XICS_RM_KICK_VCPU) {
                icp->n_rm_kick_vcpu++;
                kvmppc_fast_vcpu_kick(icp->rm_kick_target);
        }
        if (icp->rm_action & XICS_RM_CHECK_RESEND) {
                icp->n_rm_check_resend++;
                icp_check_resend(xics, icp->rm_resend_icp);
        }
        if (icp->rm_action & XICS_RM_NOTIFY_EOI) {
                icp->n_rm_notify_eoi++;
                kvm_notify_acked_irq(vcpu->kvm, 0, icp->rm_eoied_irq);
        }

        icp->rm_action = 0;

        return H_SUCCESS;
}
EXPORT_SYMBOL_GPL(kvmppc_xics_rm_complete);

int kvmppc_xics_hcall(struct kvm_vcpu *vcpu, u32 req)
{
        struct kvmppc_xics *xics = vcpu->kvm->arch.xics;
        unsigned long res;
        int rc = H_SUCCESS;

        /* Check if we have an ICP */
        if (!xics || !vcpu->arch.icp)
                return H_HARDWARE;

        /* These requests don't have real-mode implementations at present */
        switch (req) {
        case H_XIRR_X:
                res = kvmppc_h_xirr(vcpu);
                kvmppc_set_gpr(vcpu, 4, res);
                kvmppc_set_gpr(vcpu, 5, get_tb());
                return rc;
        case H_IPOLL:
                rc = kvmppc_h_ipoll(vcpu, kvmppc_get_gpr(vcpu, 4));
                return rc;
        }

        /* Check for real mode returning too hard */
        if (xics->real_mode && is_kvmppc_hv_enabled(vcpu->kvm))
                return kvmppc_xics_rm_complete(vcpu, req);

        switch (req) {
        case H_XIRR:
                res = kvmppc_h_xirr(vcpu);
                kvmppc_set_gpr(vcpu, 4, res);
                break;
        case H_CPPR:
                kvmppc_h_cppr(vcpu, kvmppc_get_gpr(vcpu, 4));
                break;
        case H_EOI:
                rc = kvmppc_h_eoi(vcpu, kvmppc_get_gpr(vcpu, 4));
                break;
        case H_IPI:
                rc = kvmppc_h_ipi(vcpu, kvmppc_get_gpr(vcpu, 4),
                                  kvmppc_get_gpr(vcpu, 5));
                break;
        }

        return rc;
}
EXPORT_SYMBOL_GPL(kvmppc_xics_hcall);


/* -- Initialisation code etc. -- */

static void xics_debugfs_irqmap(struct seq_file *m,
                                struct kvmppc_passthru_irqmap *pimap)
{
        int i;

        if (!pimap)
                return;
        seq_printf(m, "========\nPIRQ mappings: %d maps\n===========\n",
                                pimap->n_mapped);
        for (i = 0; i < pimap->n_mapped; i++)  {
                seq_printf(m, "r_hwirq=%x, v_hwirq=%x\n",
                        pimap->mapped[i].r_hwirq, pimap->mapped[i].v_hwirq);
        }
}

static int xics_debug_show(struct seq_file *m, void *private)
{
        struct kvmppc_xics *xics = m->private;
        struct kvm *kvm = xics->kvm;
        struct kvm_vcpu *vcpu;
        int icsid;
        unsigned long flags, i;
        unsigned long t_rm_kick_vcpu, t_rm_check_resend;
        unsigned long t_rm_notify_eoi;
        unsigned long t_reject, t_check_resend;

        if (!kvm)
                return 0;

        t_rm_kick_vcpu = 0;
        t_rm_notify_eoi = 0;
        t_rm_check_resend = 0;
        t_check_resend = 0;
        t_reject = 0;

        xics_debugfs_irqmap(m, kvm->arch.pimap);

        seq_printf(m, "=========\nICP state\n=========\n");

        kvm_for_each_vcpu(i, vcpu, kvm) {
                struct kvmppc_icp *icp = vcpu->arch.icp;
                union kvmppc_icp_state state;

                if (!icp)
                        continue;

                state.raw = READ_ONCE(icp->state.raw);
                seq_printf(m, "cpu server %#lx XIRR:%#x PPRI:%#x CPPR:%#x MFRR:%#x OUT:%d NR:%d\n",
                           icp->server_num, state.xisr,
                           state.pending_pri, state.cppr, state.mfrr,
                           state.out_ee, state.need_resend);
                t_rm_kick_vcpu += icp->n_rm_kick_vcpu;
                t_rm_notify_eoi += icp->n_rm_notify_eoi;
                t_rm_check_resend += icp->n_rm_check_resend;
                t_check_resend += icp->n_check_resend;
                t_reject += icp->n_reject;
        }

        seq_printf(m, "ICP Guest->Host totals: kick_vcpu=%lu check_resend=%lu notify_eoi=%lu\n",
                        t_rm_kick_vcpu, t_rm_check_resend,
                        t_rm_notify_eoi);
        seq_printf(m, "ICP Real Mode totals: check_resend=%lu resend=%lu\n",
                        t_check_resend, t_reject);
        for (icsid = 0; icsid <= KVMPPC_XICS_MAX_ICS_ID; icsid++) {
                struct kvmppc_ics *ics = xics->ics[icsid];

                if (!ics)
                        continue;

                seq_printf(m, "=========\nICS state for ICS 0x%x\n=========\n",
                           icsid);

                local_irq_save(flags);
                arch_spin_lock(&ics->lock);

                for (i = 0; i < KVMPPC_XICS_IRQ_PER_ICS; i++) {
                        struct ics_irq_state *irq = &ics->irq_state[i];

                        seq_printf(m, "irq 0x%06x: server %#x prio %#x save prio %#x pq_state %d resend %d masked pending %d\n",
                                   irq->number, irq->server, irq->priority,
                                   irq->saved_priority, irq->pq_state,
                                   irq->resend, irq->masked_pending);

                }
                arch_spin_unlock(&ics->lock);
                local_irq_restore(flags);
        }
        return 0;
}

DEFINE_SHOW_ATTRIBUTE(xics_debug);

static void xics_debugfs_init(struct kvmppc_xics *xics)
{
        xics->dentry = debugfs_create_file("xics", 0444, xics->kvm->debugfs_dentry,
                                           xics, &xics_debug_fops);

        pr_debug("%s: created\n", __func__);
}

static struct kvmppc_ics *kvmppc_xics_create_ics(struct kvm *kvm,
                                        struct kvmppc_xics *xics, int irq)
{
        struct kvmppc_ics *ics;
        int i, icsid;

        icsid = irq >> KVMPPC_XICS_ICS_SHIFT;

        mutex_lock(&kvm->lock);

        /* ICS already exists - somebody else got here first */
        if (xics->ics[icsid])
                goto out;

        /* Create the ICS */
        ics = kzalloc_obj(struct kvmppc_ics);
        if (!ics)
                goto out;

        ics->icsid = icsid;

        for (i = 0; i < KVMPPC_XICS_IRQ_PER_ICS; i++) {
                ics->irq_state[i].number = (icsid << KVMPPC_XICS_ICS_SHIFT) | i;
                ics->irq_state[i].priority = MASKED;
                ics->irq_state[i].saved_priority = MASKED;
        }
        smp_wmb();
        xics->ics[icsid] = ics;

        if (icsid > xics->max_icsid)
                xics->max_icsid = icsid;

 out:
        mutex_unlock(&kvm->lock);
        return xics->ics[icsid];
}

static int kvmppc_xics_create_icp(struct kvm_vcpu *vcpu, unsigned long server_num)
{
        struct kvmppc_icp *icp;

        if (!vcpu->kvm->arch.xics)
                return -ENODEV;

        if (kvmppc_xics_find_server(vcpu->kvm, server_num))
                return -EEXIST;

        icp = kzalloc_obj(struct kvmppc_icp);
        if (!icp)
                return -ENOMEM;

        icp->vcpu = vcpu;
        icp->server_num = server_num;
        icp->state.mfrr = MASKED;
        icp->state.pending_pri = MASKED;
        vcpu->arch.icp = icp;

        XICS_DBG("created server for vcpu %d\n", vcpu->vcpu_id);

        return 0;
}

u64 kvmppc_xics_get_icp(struct kvm_vcpu *vcpu)
{
        struct kvmppc_icp *icp = vcpu->arch.icp;
        union kvmppc_icp_state state;

        if (!icp)
                return 0;
        state = icp->state;
        return ((u64)state.cppr << KVM_REG_PPC_ICP_CPPR_SHIFT) |
                ((u64)state.xisr << KVM_REG_PPC_ICP_XISR_SHIFT) |
                ((u64)state.mfrr << KVM_REG_PPC_ICP_MFRR_SHIFT) |
                ((u64)state.pending_pri << KVM_REG_PPC_ICP_PPRI_SHIFT);
}

int kvmppc_xics_set_icp(struct kvm_vcpu *vcpu, u64 icpval)
{
        struct kvmppc_icp *icp = vcpu->arch.icp;
        struct kvmppc_xics *xics = vcpu->kvm->arch.xics;
        union kvmppc_icp_state old_state, new_state;
        struct kvmppc_ics *ics;
        u8 cppr, mfrr, pending_pri;
        u32 xisr;
        u16 src;
        bool resend;

        if (!icp || !xics)
                return -ENOENT;

        cppr = icpval >> KVM_REG_PPC_ICP_CPPR_SHIFT;
        xisr = (icpval >> KVM_REG_PPC_ICP_XISR_SHIFT) &
                KVM_REG_PPC_ICP_XISR_MASK;
        mfrr = icpval >> KVM_REG_PPC_ICP_MFRR_SHIFT;
        pending_pri = icpval >> KVM_REG_PPC_ICP_PPRI_SHIFT;

        /* Require the new state to be internally consistent */
        if (xisr == 0) {
                if (pending_pri != 0xff)
                        return -EINVAL;
        } else if (xisr == XICS_IPI) {
                if (pending_pri != mfrr || pending_pri >= cppr)
                        return -EINVAL;
        } else {
                if (pending_pri >= mfrr || pending_pri >= cppr)
                        return -EINVAL;
                ics = kvmppc_xics_find_ics(xics, xisr, &src);
                if (!ics)
                        return -EINVAL;
        }

        new_state.raw = 0;
        new_state.cppr = cppr;
        new_state.xisr = xisr;
        new_state.mfrr = mfrr;
        new_state.pending_pri = pending_pri;

        /*
         * Deassert the CPU interrupt request.
         * icp_try_update will reassert it if necessary.
         */
        kvmppc_book3s_dequeue_irqprio(icp->vcpu, BOOK3S_INTERRUPT_EXTERNAL);

        /*
         * Note that if we displace an interrupt from old_state.xisr,
         * we don't mark it as rejected.  We expect userspace to set
         * the state of the interrupt sources to be consistent with
         * the ICP states (either before or afterwards, which doesn't
         * matter).  We do handle resends due to CPPR becoming less
         * favoured because that is necessary to end up with a
         * consistent state in the situation where userspace restores
         * the ICS states before the ICP states.
         */
        do {
                old_state = READ_ONCE(icp->state);

                if (new_state.mfrr <= old_state.mfrr) {
                        resend = false;
                        new_state.need_resend = old_state.need_resend;
                } else {
                        resend = old_state.need_resend;
                        new_state.need_resend = 0;
                }
        } while (!icp_try_update(icp, old_state, new_state, false));

        if (resend)
                icp_check_resend(xics, icp);

        return 0;
}

static int xics_get_source(struct kvmppc_xics *xics, long irq, u64 addr)
{
        int ret;
        struct kvmppc_ics *ics;
        struct ics_irq_state *irqp;
        u64 __user *ubufp = (u64 __user *) addr;
        u16 idx;
        u64 val, prio;
        unsigned long flags;

        ics = kvmppc_xics_find_ics(xics, irq, &idx);
        if (!ics)
                return -ENOENT;

        irqp = &ics->irq_state[idx];
        local_irq_save(flags);
        arch_spin_lock(&ics->lock);
        ret = -ENOENT;
        if (irqp->exists) {
                val = irqp->server;
                prio = irqp->priority;
                if (prio == MASKED) {
                        val |= KVM_XICS_MASKED;
                        prio = irqp->saved_priority;
                }
                val |= prio << KVM_XICS_PRIORITY_SHIFT;
                if (irqp->lsi) {
                        val |= KVM_XICS_LEVEL_SENSITIVE;
                        if (irqp->pq_state & PQ_PRESENTED)
                                val |= KVM_XICS_PENDING;
                } else if (irqp->masked_pending || irqp->resend)
                        val |= KVM_XICS_PENDING;

                if (irqp->pq_state & PQ_PRESENTED)
                        val |= KVM_XICS_PRESENTED;

                if (irqp->pq_state & PQ_QUEUED)
                        val |= KVM_XICS_QUEUED;

                ret = 0;
        }
        arch_spin_unlock(&ics->lock);
        local_irq_restore(flags);

        if (!ret && put_user(val, ubufp))
                ret = -EFAULT;

        return ret;
}

static int xics_set_source(struct kvmppc_xics *xics, long irq, u64 addr)
{
        struct kvmppc_ics *ics;
        struct ics_irq_state *irqp;
        u64 __user *ubufp = (u64 __user *) addr;
        u16 idx;
        u64 val;
        u8 prio;
        u32 server;
        unsigned long flags;

        if (irq < KVMPPC_XICS_FIRST_IRQ || irq >= KVMPPC_XICS_NR_IRQS)
                return -ENOENT;

        ics = kvmppc_xics_find_ics(xics, irq, &idx);
        if (!ics) {
                ics = kvmppc_xics_create_ics(xics->kvm, xics, irq);
                if (!ics)
                        return -ENOMEM;
        }
        irqp = &ics->irq_state[idx];
        if (get_user(val, ubufp))
                return -EFAULT;

        server = val & KVM_XICS_DESTINATION_MASK;
        prio = val >> KVM_XICS_PRIORITY_SHIFT;
        if (prio != MASKED &&
            kvmppc_xics_find_server(xics->kvm, server) == NULL)
                return -EINVAL;

        local_irq_save(flags);
        arch_spin_lock(&ics->lock);
        irqp->server = server;
        irqp->saved_priority = prio;
        if (val & KVM_XICS_MASKED)
                prio = MASKED;
        irqp->priority = prio;
        irqp->resend = 0;
        irqp->masked_pending = 0;
        irqp->lsi = 0;
        irqp->pq_state = 0;
        if (val & KVM_XICS_LEVEL_SENSITIVE)
                irqp->lsi = 1;
        /* If PENDING, set P in case P is not saved because of old code */
        if (val & KVM_XICS_PRESENTED || val & KVM_XICS_PENDING)
                irqp->pq_state |= PQ_PRESENTED;
        if (val & KVM_XICS_QUEUED)
                irqp->pq_state |= PQ_QUEUED;
        irqp->exists = 1;
        arch_spin_unlock(&ics->lock);
        local_irq_restore(flags);

        if (val & KVM_XICS_PENDING)
                icp_deliver_irq(xics, NULL, irqp->number, false);

        return 0;
}

int kvmppc_xics_set_irq(struct kvm *kvm, int irq_source_id, u32 irq, int level,
                        bool line_status)
{
        struct kvmppc_xics *xics = kvm->arch.xics;

        if (!xics)
                return -ENODEV;
        return ics_deliver_irq(xics, irq, level);
}

static int xics_set_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
{
        struct kvmppc_xics *xics = dev->private;

        switch (attr->group) {
        case KVM_DEV_XICS_GRP_SOURCES:
                return xics_set_source(xics, attr->attr, attr->addr);
        }
        return -ENXIO;
}

static int xics_get_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
{
        struct kvmppc_xics *xics = dev->private;

        switch (attr->group) {
        case KVM_DEV_XICS_GRP_SOURCES:
                return xics_get_source(xics, attr->attr, attr->addr);
        }
        return -ENXIO;
}

static int xics_has_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
{
        switch (attr->group) {
        case KVM_DEV_XICS_GRP_SOURCES:
                if (attr->attr >= KVMPPC_XICS_FIRST_IRQ &&
                    attr->attr < KVMPPC_XICS_NR_IRQS)
                        return 0;
                break;
        }
        return -ENXIO;
}

/*
 * Called when device fd is closed. kvm->lock is held.
 */
static void kvmppc_xics_release(struct kvm_device *dev)
{
        struct kvmppc_xics *xics = dev->private;
        unsigned long i;
        struct kvm *kvm = xics->kvm;
        struct kvm_vcpu *vcpu;

        pr_devel("Releasing xics device\n");

        /*
         * Since this is the device release function, we know that
         * userspace does not have any open fd referring to the
         * device.  Therefore there can not be any of the device
         * attribute set/get functions being executed concurrently,
         * and similarly, the connect_vcpu and set/clr_mapped
         * functions also cannot be being executed.
         */

        debugfs_remove(xics->dentry);

        /*
         * We should clean up the vCPU interrupt presenters first.
         */
        kvm_for_each_vcpu(i, vcpu, kvm) {
                /*
                 * Take vcpu->mutex to ensure that no one_reg get/set ioctl
                 * (i.e. kvmppc_xics_[gs]et_icp) can be done concurrently.
                 * Holding the vcpu->mutex also means that execution is
                 * excluded for the vcpu until the ICP was freed. When the vcpu
                 * can execute again, vcpu->arch.icp and vcpu->arch.irq_type
                 * have been cleared and the vcpu will not be going into the
                 * XICS code anymore.
                 */
                mutex_lock(&vcpu->mutex);
                kvmppc_xics_free_icp(vcpu);
                mutex_unlock(&vcpu->mutex);
        }

        if (kvm)
                kvm->arch.xics = NULL;

        for (i = 0; i <= xics->max_icsid; i++) {
                kfree(xics->ics[i]);
                xics->ics[i] = NULL;
        }
        /*
         * A reference of the kvmppc_xics pointer is now kept under
         * the xics_device pointer of the machine for reuse. It is
         * freed when the VM is destroyed for now until we fix all the
         * execution paths.
         */
        kfree(dev);
}

static struct kvmppc_xics *kvmppc_xics_get_device(struct kvm *kvm)
{
        struct kvmppc_xics **kvm_xics_device = &kvm->arch.xics_device;
        struct kvmppc_xics *xics = *kvm_xics_device;

        if (!xics) {
                xics = kzalloc_obj(*xics);
                *kvm_xics_device = xics;
        } else {
                memset(xics, 0, sizeof(*xics));
        }

        return xics;
}

static int kvmppc_xics_create(struct kvm_device *dev, u32 type)
{
        struct kvmppc_xics *xics;
        struct kvm *kvm = dev->kvm;

        pr_devel("Creating xics for partition\n");

        /* Already there ? */
        if (kvm->arch.xics)
                return -EEXIST;

        xics = kvmppc_xics_get_device(kvm);
        if (!xics)
                return -ENOMEM;

        dev->private = xics;
        xics->dev = dev;
        xics->kvm = kvm;
        kvm->arch.xics = xics;

#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
        if (cpu_has_feature(CPU_FTR_ARCH_206) &&
            cpu_has_feature(CPU_FTR_HVMODE)) {
                /* Enable real mode support */
                xics->real_mode = ENABLE_REALMODE;
                xics->real_mode_dbg = DEBUG_REALMODE;
        }
#endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */

        return 0;
}

static void kvmppc_xics_init(struct kvm_device *dev)
{
        struct kvmppc_xics *xics = dev->private;

        xics_debugfs_init(xics);
}

struct kvm_device_ops kvm_xics_ops = {
        .name = "kvm-xics",
        .create = kvmppc_xics_create,
        .init = kvmppc_xics_init,
        .release = kvmppc_xics_release,
        .set_attr = xics_set_attr,
        .get_attr = xics_get_attr,
        .has_attr = xics_has_attr,
};

int kvmppc_xics_connect_vcpu(struct kvm_device *dev, struct kvm_vcpu *vcpu,
                             u32 xcpu)
{
        struct kvmppc_xics *xics = dev->private;
        int r = -EBUSY;

        if (dev->ops != &kvm_xics_ops)
                return -EPERM;
        if (xics->kvm != vcpu->kvm)
                return -EPERM;
        if (vcpu->arch.irq_type != KVMPPC_IRQ_DEFAULT)
                return -EBUSY;

        r = kvmppc_xics_create_icp(vcpu, xcpu);
        if (!r)
                vcpu->arch.irq_type = KVMPPC_IRQ_XICS;

        return r;
}

void kvmppc_xics_free_icp(struct kvm_vcpu *vcpu)
{
        if (!vcpu->arch.icp)
                return;
        kfree(vcpu->arch.icp);
        vcpu->arch.icp = NULL;
        vcpu->arch.irq_type = KVMPPC_IRQ_DEFAULT;
}

void kvmppc_xics_set_mapped(struct kvm *kvm, unsigned long irq,
                            unsigned long host_irq)
{
        struct kvmppc_xics *xics = kvm->arch.xics;
        struct kvmppc_ics *ics;
        u16 idx;

        ics = kvmppc_xics_find_ics(xics, irq, &idx);
        if (!ics)
                return;

        ics->irq_state[idx].host_irq = host_irq;
        ics->irq_state[idx].intr_cpu = -1;
}
EXPORT_SYMBOL_GPL(kvmppc_xics_set_mapped);

void kvmppc_xics_clr_mapped(struct kvm *kvm, unsigned long irq,
                            unsigned long host_irq)
{
        struct kvmppc_xics *xics = kvm->arch.xics;
        struct kvmppc_ics *ics;
        u16 idx;

        ics = kvmppc_xics_find_ics(xics, irq, &idx);
        if (!ics)
                return;

        ics->irq_state[idx].host_irq = 0;
}
EXPORT_SYMBOL_GPL(kvmppc_xics_clr_mapped);