/*
   * irqchip.c: Common API for in kernel interrupt controllers
   * Copyright (c) 2007, Intel Corporation.
   * Copyright 2010 Red Hat, Inc. and/or its affiliates.
   * Copyright (c) 2013, Alexander Graf <agraf@suse.de>
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms and conditions of the GNU General Public License,
   * version 2, as published by the Free Software Foundation.
   *
   * This program is distributed in the hope it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
   * more details.
   *
   * You should have received a copy of the GNU General Public License along with
   * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
   * Place - Suite 330, Boston, MA 02111-1307 USA.
   *
   * This file is derived from virt/kvm/irq_comm.c.
   *
   * Authors:
   *   Yaozu (Eddie) Dong <Eddie.dong@intel.com>
   *   Alexander Graf <agraf@suse.de>
   */
  
  #include <linux/kvm_host.h>
  #include <linux/slab.h>
  #include <linux/srcu.h>
  #include <linux/export.h>
  #include <trace/events/kvm.h>
  #include "irq.h"
  
  int kvm_irq_map_gsi(struct kvm *kvm,
  		    struct kvm_kernel_irq_routing_entry *entries, int gsi)
  {
  	struct kvm_irq_routing_table *irq_rt;
  	struct kvm_kernel_irq_routing_entry *e;
  	int n = 0;
  
  	irq_rt = srcu_dereference_check(kvm->irq_routing, &kvm->irq_srcu,
  					lockdep_is_held(&kvm->irq_lock));
  	if (irq_rt && gsi < irq_rt->nr_rt_entries) {
  		hlist_for_each_entry(e, &irq_rt->map[gsi], link) {
  			entries[n] = *e;
  			++n;
  		}
  	}
  
  	return n;
  }
  
  int kvm_irq_map_chip_pin(struct kvm *kvm, unsigned irqchip, unsigned pin)
  {
  	struct kvm_irq_routing_table *irq_rt;
  
  	irq_rt = srcu_dereference(kvm->irq_routing, &kvm->irq_srcu);
  	return irq_rt->chip[irqchip][pin];
  }
  
  int kvm_send_userspace_msi(struct kvm *kvm, struct kvm_msi *msi)
  {
  	struct kvm_kernel_irq_routing_entry route;
  
  	if (!irqchip_in_kernel(kvm) || msi->flags != 0)
  		return -EINVAL;
  
  	route.msi.address_lo = msi->address_lo;
  	route.msi.address_hi = msi->address_hi;
  	route.msi.data = msi->data;
  
  	return kvm_set_msi(&route, kvm, KVM_USERSPACE_IRQ_SOURCE_ID, 1, false);
  }
  
  /*
   * Return value:
   *  < 0   Interrupt was ignored (masked or not delivered for other reasons)
   *  = 0   Interrupt was coalesced (previous irq is still pending)
   *  > 0   Number of CPUs interrupt was delivered to
   */
  int kvm_set_irq(struct kvm *kvm, int irq_source_id, u32 irq, int level,
  		bool line_status)
  {
  	struct kvm_kernel_irq_routing_entry irq_set[KVM_NR_IRQCHIPS];
  	int ret = -1, i, idx;
  
  	trace_kvm_set_irq(irq, level, irq_source_id);
  
  	/* Not possible to detect if the guest uses the PIC or the
  	 * IOAPIC.  So set the bit in both. The guest will ignore
  	 * writes to the unused one.
  	 */
  	idx = srcu_read_lock(&kvm->irq_srcu);
  	i = kvm_irq_map_gsi(kvm, irq_set, irq);
  	srcu_read_unlock(&kvm->irq_srcu, idx);
  
  	while (i--) {
  		int r;
  		r = irq_set[i].set(&irq_set[i], kvm, irq_source_id, level,
  				   line_status);
  		if (r < 0)
  			continue;
  
  		ret = r + ((ret < 0) ? 0 : ret);
  	}
  
  	return ret;
  }
  
  static void free_irq_routing_table(struct kvm_irq_routing_table *rt)
  {
  	int i;
  
  	if (!rt)
  		return;
  
  	for (i = 0; i < rt->nr_rt_entries; ++i) {
  		struct kvm_kernel_irq_routing_entry *e;
  		struct hlist_node *n;
  
  		hlist_for_each_entry_safe(e, n, &rt->map[i], link) {
  			hlist_del(&e->link);
  			kfree(e);
  		}
  	}
  
  	kfree(rt);
  }
  
  void kvm_free_irq_routing(struct kvm *kvm)
  {
  	/* Called only during vm destruction. Nobody can use the pointer
  	   at this stage */
  	struct kvm_irq_routing_table *rt = rcu_access_pointer(kvm->irq_routing);
  	free_irq_routing_table(rt);
  }
  
  static int setup_routing_entry(struct kvm_irq_routing_table *rt,
  			       struct kvm_kernel_irq_routing_entry *e,
  			       const struct kvm_irq_routing_entry *ue)
  {
  	int r = -EINVAL;
  	struct kvm_kernel_irq_routing_entry *ei;
  
  	/*
  	 * Do not allow GSI to be mapped to the same irqchip more than once.
  	 * Allow only one to one mapping between GSI and non-irqchip routing.
  	 */
  	hlist_for_each_entry(ei, &rt->map[ue->gsi], link)
  		if (ei->type != KVM_IRQ_ROUTING_IRQCHIP ||
  		    ue->type != KVM_IRQ_ROUTING_IRQCHIP ||
  		    ue->u.irqchip.irqchip == ei->irqchip.irqchip)
  			return r;
  
  	e->gsi = ue->gsi;
  	e->type = ue->type;
  	r = kvm_set_routing_entry(e, ue);
  	if (r)
  		goto out;
  	if (e->type == KVM_IRQ_ROUTING_IRQCHIP)
  		rt->chip[e->irqchip.irqchip][e->irqchip.pin] = e->gsi;
  
  	hlist_add_head(&e->link, &rt->map[e->gsi]);
  	r = 0;
  out:
  	return r;
  }
  
  int kvm_set_irq_routing(struct kvm *kvm,
  			const struct kvm_irq_routing_entry *ue,
  			unsigned nr,
  			unsigned flags)
  {
  	struct kvm_irq_routing_table *new, *old;
  	u32 i, j, nr_rt_entries = 0;
  	int r;
  
  	for (i = 0; i < nr; ++i) {
  		if (ue[i].gsi >= KVM_MAX_IRQ_ROUTES)
  			return -EINVAL;
  		nr_rt_entries = max(nr_rt_entries, ue[i].gsi);
  	}
  
  	nr_rt_entries += 1;
  
  	new = kzalloc(sizeof(*new) + (nr_rt_entries * sizeof(struct hlist_head)),
  		      GFP_KERNEL);
  
  	if (!new)
  		return -ENOMEM;
  
  	new->nr_rt_entries = nr_rt_entries;
  	for (i = 0; i < KVM_NR_IRQCHIPS; i++)
  		for (j = 0; j < KVM_IRQCHIP_NUM_PINS; j++)
  			new->chip[i][j] = -1;
  
  	for (i = 0; i < nr; ++i) {
  		struct kvm_kernel_irq_routing_entry *e;
  
  		r = -ENOMEM;
  		e = kzalloc(sizeof(*e), GFP_KERNEL);
  		if (!e)
  			goto out;
  
  		r = -EINVAL;
  		if (ue->flags) {
  			kfree(e);
  			goto out;
  		}
  		r = setup_routing_entry(new, e, ue);
  		if (r) {
  			kfree(e);
  			goto out;
  		}
  		++ue;
  	}
  
  	mutex_lock(&kvm->irq_lock);
  	old = kvm->irq_routing;
  	rcu_assign_pointer(kvm->irq_routing, new);
  	kvm_irq_routing_update(kvm);
  	mutex_unlock(&kvm->irq_lock);
  
  	kvm_arch_irq_routing_update(kvm);
  
  	synchronize_srcu_expedited(&kvm->irq_srcu);
  
  	new = old;
  	r = 0;
  
  out:
  	free_irq_routing_table(new);
  
  	return r;
  }