text: /*
   * Copyright 2012 Michael Ellerman, IBM Corporation.
   * Copyright 2012 Benjamin Herrenschmidt, IBM Corporation.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License, version 2, as
   * published by the Free Software Foundation.
   */
  
  #include <linux/kernel.h>
  #include <linux/kvm_host.h>
  #include <linux/err.h>
  #include <linux/gfp.h>
  #include <linux/anon_inodes.h>
  
  #include <asm/uaccess.h>
  #include <asm/kvm_book3s.h>
  #include <asm/kvm_ppc.h>
  #include <asm/hvcall.h>
  #include <asm/xics.h>
  #include <asm/debug.h>
  #include <asm/time.h>
  
  #include <linux/debugfs.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 mutex protecting the information about the IRQ
   * sources and avoiding simultaneous deliveries if 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);
  
  static int ics_deliver_irq(struct kvmppc_xics *xics, u32 irq, u32 level,
  			   bool report_status)
  {
  	struct ics_irq_state *state;
  	struct kvmppc_ics *ics;
  	u16 src;
  
  	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 (report_status)
  		return state->asserted;
  
  	/*
  	 * We set state->asserted locklessly. This should be fine as
  	 * we are the only setter, thus concurrent access is undefined
  	 * to begin with.
  	 */
  	if (level == KVM_INTERRUPT_SET_LEVEL)
  		state->asserted = 1;
  	else if (level == KVM_INTERRUPT_UNSET) {
  		state->asserted = 0;
  		return 0;
  	}
  
  	/* Attempt delivery */
  	icp_deliver_irq(xics, NULL, irq);
  
  	return state->asserted;
  }
  
  static void ics_check_resend(struct kvmppc_xics *xics, struct kvmppc_ics *ics,
  			     struct kvmppc_icp *icp)
  {
  	int i;
  
  	mutex_lock(&ics->lock);
  
  	for (i = 0; i < KVMPPC_XICS_IRQ_PER_ICS; i++) {
  		struct ics_irq_state *state = &ics->irq_state[i];
  
  		if (!state->resend)
  			continue;
  
  		XICS_DBG("resend %#x prio %#x\n", state->number,
  			      state->priority);
  
  		mutex_unlock(&ics->lock);
  		icp_deliver_irq(xics, icp, state->number);
  		mutex_lock(&ics->lock);
  	}
  
  	mutex_unlock(&ics->lock);
  }
  
  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;
  
  	mutex_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;
  		deliver = true;
  	}
  
  	mutex_unlock(&ics->lock);
  
  	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);
  
  	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;
  
  	if (!xics)
  		return -ENODEV;
  
  	ics = kvmppc_xics_find_ics(xics, irq, &src);
  	if (!ics)
  		return -EINVAL;
  	state = &ics->irq_state[src];
  
  	mutex_lock(&ics->lock);
  	*server = state->server;
  	*priority = state->priority;
  	mutex_unlock(&ics->lock);
  
  	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);
  
  	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 [%04x] - 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_LEVEL);
  		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 %#x\n", irq, priority,
  		 icp->server_num);
  
  	do {
  		old_state = new_state = ACCESS_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)
  {
  	struct ics_irq_state *state;
  	struct kvmppc_ics *ics;
  	u32 reject;
  	u16 src;
  
  	/*
  	 * 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 */
  	mutex_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;
  		}
  	}
  
  	/* 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 differenciate 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
  	 * icp mutex.
  	 *
  	 * 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 alrady 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) {
  			mutex_unlock(&ics->lock);
  			new_irq = reject;
  			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
  		 */
  		set_bit(ics->icsid, icp->resend_map);
  		state->resend = 1;
  
  		/*
  		 * 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) {
  			mutex_unlock(&ics->lock);
  			goto again;
  		}
  	}
   out:
  	mutex_unlock(&ics->lock);
  }
  
  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 = ACCESS_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_LEVEL);
  
  	/*
  	 * 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 = ACCESS_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.
  	 *
  	 * If the CPPR is less favored, then we might be replacing
  	 * an interrupt, and thus need to possibly reject it as in
  	 *
  	 * ICP state: Check_IPI
  	 */
  	do {
  		old_state = new_state = ACCESS_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 && mfrr > new_state.cppr) {
  			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);
  
  	/* 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 = ACCESS_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_LEVEL);
  
  	do {
  		old_state = new_state = ACCESS_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);
  }
  
  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;
  	struct kvmppc_ics *ics;
  	struct ics_irq_state *state;
  	u32 irq = xirr & 0x00ffffff;
  	u16 src;
  
  	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 sepcifies
  	 * 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;
  	/*
  	 * EOI handling: If the interrupt is still asserted, we need to
  	 * resend it. We can take a lockless "peek" at the ICS state here.
  	 *
  	 * "Message" interrupts will never have "asserted" set
  	 */
  	ics = kvmppc_xics_find_ics(xics, irq, &src);
  	if (!ics) {
  		XICS_DBG("h_eoi: IRQ 0x%06x not found !\n", irq);
  		return H_PARAMETER;
  	}
  	state = &ics->irq_state[src];
  
  	/* Still asserted, resend it */
  	if (state->asserted)
  		icp_deliver_irq(xics, icp, irq);
  
  	return H_SUCCESS;
  }
  
  static noinline 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)
  		kvmppc_fast_vcpu_kick(icp->rm_kick_target);
  	if (icp->rm_action & XICS_RM_CHECK_RESEND)
  		icp_check_resend(xics, icp);
  	if (icp->rm_action & XICS_RM_REJECT)
  		icp_deliver_irq(xics, icp, icp->rm_reject);
  
  	icp->rm_action = 0;
  
  	return H_SUCCESS;
  }
  
  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 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, i;
  
  	if (!kvm)
  		return 0;
  
  	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 = ACCESS_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);
  	}
  
  	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);
  
  		mutex_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 asserted %d resend %d masked pending %d\n",
  				   irq->number, irq->server, irq->priority,
  				   irq->saved_priority, irq->asserted,
  				   irq->resend, irq->masked_pending);
  
  		}
  		mutex_unlock(&ics->lock);
  	}
  	return 0;
  }
  
  static int xics_debug_open(struct inode *inode, struct file *file)
  {
  	return single_open(file, xics_debug_show, inode->i_private);
  }
  
  static const struct file_operations xics_debug_fops = {
  	.open = xics_debug_open,
  	.read = seq_read,
  	.llseek = seq_lseek,
  	.release = single_release,
  };
  
  static void xics_debugfs_init(struct kvmppc_xics *xics)
  {
  	char *name;
  
  	name = kasprintf(GFP_KERNEL, "kvm-xics-%p", xics);
  	if (!name) {
  		pr_err("%s: no memory for name\n", __func__);
  		return;
  	}
  
  	xics->dentry = debugfs_create_file(name, S_IRUGO, powerpc_debugfs_root,
  					   xics, &xics_debug_fops);
  
  	pr_debug("%s: created %s\n", __func__, name);
  	kfree(name);
  }
  
  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(sizeof(struct kvmppc_ics), GFP_KERNEL);
  	if (!ics)
  		goto out;
  
  	mutex_init(&ics->lock);
  	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];
  }
  
  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(sizeof(struct kvmppc_icp), GFP_KERNEL);
  	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_LEVEL);
  
  	/*
  	 * 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 = ACCESS_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;
  
  	ics = kvmppc_xics_find_ics(xics, irq, &idx);
  	if (!ics)
  		return -ENOENT;
  
  	irqp = &ics->irq_state[idx];
  	mutex_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->asserted)
  			val |= KVM_XICS_LEVEL_SENSITIVE | KVM_XICS_PENDING;
  		else if (irqp->masked_pending || irqp->resend)
  			val |= KVM_XICS_PENDING;
  		ret = 0;
  	}
  	mutex_unlock(&ics->lock);
  
  	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;
  
  	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;
  
  	mutex_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->asserted = 0;
  	if ((val & KVM_XICS_PENDING) && (val & KVM_XICS_LEVEL_SENSITIVE))
  		irqp->asserted = 1;
  	irqp->exists = 1;
  	mutex_unlock(&ics->lock);
  
  	if (val & KVM_XICS_PENDING)
  		icp_deliver_irq(xics, NULL, irqp->number);
  
  	return 0;
  }
  
  int kvm_set_irq(struct kvm *kvm, int irq_source_id, u32 irq, int level,
  		bool line_status)
  {
  	struct kvmppc_xics *xics = kvm->arch.xics;
  
  	return ics_deliver_irq(xics, irq, level, line_status);
  }
  
  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;
  }
  
  static void kvmppc_xics_free(struct kvm_device *dev)
  {
  	struct kvmppc_xics *xics = dev->private;
  	int i;
  	struct kvm *kvm = xics->kvm;
  
  	debugfs_remove(xics->dentry);
  
  	if (kvm)
  		kvm->arch.xics = NULL;
  
  	for (i = 0; i <= xics->max_icsid; i++)
  		kfree(xics->ics[i]);
  	kfree(xics);
  	kfree(dev);
  }
  
  static int kvmppc_xics_create(struct kvm_device *dev, u32 type)
  {
  	struct kvmppc_xics *xics;
  	struct kvm *kvm = dev->kvm;
  	int ret = 0;
  
  	xics = kzalloc(sizeof(*xics), GFP_KERNEL);
  	if (!xics)
  		return -ENOMEM;
  
  	dev->private = xics;
  	xics->dev = dev;
  	xics->kvm = kvm;
  
  	/* Already there ? */
  	mutex_lock(&kvm->lock);
  	if (kvm->arch.xics)
  		ret = -EEXIST;
  	else
  		kvm->arch.xics = xics;
  	mutex_unlock(&kvm->lock);
  
  	if (ret) {
  		kfree(xics);
  		return ret;
  	}
  
  	xics_debugfs_init(xics);
  
  #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
  	if (cpu_has_feature(CPU_FTR_ARCH_206)) {
  		/* Enable real mode support */
  		xics->real_mode = ENABLE_REALMODE;
  		xics->real_mode_dbg = DEBUG_REALMODE;
  	}
  #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */
  
  	return 0;
  }
  
  struct kvm_device_ops kvm_xics_ops = {
  	.name = "kvm-xics",
  	.create = kvmppc_xics_create,
  	.destroy = kvmppc_xics_free,
  	.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)
  		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;
  }
  