/*
   * KVM coalesced MMIO
   *
   * Copyright (c) 2008 Bull S.A.S.

   * Copyright 2009 Red Hat, Inc. and/or its affiliates.

   *
   *  Author: Laurent Vivier <Laurent.Vivier@bull.net>
   *
   */
  
  #include "iodev.h"
  
  #include <linux/kvm_host.h>

  #include <linux/slab.h>

  #include <linux/kvm.h>
  
  #include "coalesced_mmio.h"

  static inline struct kvm_coalesced_mmio_dev *to_mmio(struct kvm_io_device *dev)
  {
  	return container_of(dev, struct kvm_coalesced_mmio_dev, dev);
  }

  static int coalesced_mmio_in_range(struct kvm_coalesced_mmio_dev *dev,
  				   gpa_t addr, int len)

  {

  	struct kvm_coalesced_mmio_zone *zone;

  	struct kvm_coalesced_mmio_ring *ring;
  	unsigned avail;

  	int i;

  	/* Are we able to batch it ? */
  
  	/* last is the first free entry
  	 * check if we don't meet the first used entry
  	 * there is always one unused entry in the buffer
  	 */

  	ring = dev->kvm->coalesced_mmio_ring;
  	avail = (ring->first - ring->last - 1) % KVM_COALESCED_MMIO_MAX;

  	if (avail < KVM_MAX_VCPUS) {

  		/* full */
  		return 0;
  	}
  
  	/* is it in a batchable area ? */
  
  	for (i = 0; i < dev->nb_zones; i++) {
  		zone = &dev->zone[i];
  
  		/* (addr,len) is fully included in
  		 * (zone->addr, zone->size)
  		 */
  
  		if (zone->addr <= addr &&
  		    addr + len <= zone->addr + zone->size)
  			return 1;
  	}
  	return 0;
  }

  static int coalesced_mmio_write(struct kvm_io_device *this,
  				gpa_t addr, int len, const void *val)

  {

  	struct kvm_coalesced_mmio_dev *dev = to_mmio(this);

  	struct kvm_coalesced_mmio_ring *ring = dev->kvm->coalesced_mmio_ring;

  	if (!coalesced_mmio_in_range(dev, addr, len))
  		return -EOPNOTSUPP;

  	spin_lock(&dev->lock);

  
  	/* copy data in first free entry of the ring */
  
  	ring->coalesced_mmio[ring->last].phys_addr = addr;
  	ring->coalesced_mmio[ring->last].len = len;
  	memcpy(ring->coalesced_mmio[ring->last].data, val, len);
  	smp_wmb();
  	ring->last = (ring->last + 1) % KVM_COALESCED_MMIO_MAX;

  	spin_unlock(&dev->lock);

  	return 0;

  }
  
  static void coalesced_mmio_destructor(struct kvm_io_device *this)
  {

  	struct kvm_coalesced_mmio_dev *dev = to_mmio(this);

  
  	kfree(dev);

  }

  static const struct kvm_io_device_ops coalesced_mmio_ops = {
  	.write      = coalesced_mmio_write,

  	.destructor = coalesced_mmio_destructor,
  };

  int kvm_coalesced_mmio_init(struct kvm *kvm)
  {
  	struct kvm_coalesced_mmio_dev *dev;

  	struct page *page;

  	int ret;

  	ret = -ENOMEM;
  	page = alloc_page(GFP_KERNEL | __GFP_ZERO);
  	if (!page)
  		goto out_err;
  	kvm->coalesced_mmio_ring = page_address(page);
  
  	ret = -ENOMEM;

  	dev = kzalloc(sizeof(struct kvm_coalesced_mmio_dev), GFP_KERNEL);
  	if (!dev)

  		goto out_free_page;

  	spin_lock_init(&dev->lock);

  	kvm_iodevice_init(&dev->dev, &coalesced_mmio_ops);

  	dev->kvm = kvm;
  	kvm->coalesced_mmio_dev = dev;

  	mutex_lock(&kvm->slots_lock);

  	ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, &dev->dev);

  	mutex_unlock(&kvm->slots_lock);

  	if (ret < 0)

  		goto out_free_dev;
  
  	return ret;

  out_free_dev:

  	kvm->coalesced_mmio_dev = NULL;

  	kfree(dev);
  out_free_page:

  	kvm->coalesced_mmio_ring = NULL;

  	__free_page(page);
  out_err:

  	return ret;

  }

  void kvm_coalesced_mmio_free(struct kvm *kvm)
  {
  	if (kvm->coalesced_mmio_ring)
  		free_page((unsigned long)kvm->coalesced_mmio_ring);
  }

  int kvm_vm_ioctl_register_coalesced_mmio(struct kvm *kvm,

  					 struct kvm_coalesced_mmio_zone *zone)

  {
  	struct kvm_coalesced_mmio_dev *dev = kvm->coalesced_mmio_dev;
  
  	if (dev == NULL)

  		return -ENXIO;

  	mutex_lock(&kvm->slots_lock);

  	if (dev->nb_zones >= KVM_COALESCED_MMIO_ZONE_MAX) {

  		mutex_unlock(&kvm->slots_lock);

  		return -ENOBUFS;
  	}
  
  	dev->zone[dev->nb_zones] = *zone;
  	dev->nb_zones++;

  	mutex_unlock(&kvm->slots_lock);

  	return 0;
  }
  
  int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm,
  					   struct kvm_coalesced_mmio_zone *zone)
  {
  	int i;
  	struct kvm_coalesced_mmio_dev *dev = kvm->coalesced_mmio_dev;
  	struct kvm_coalesced_mmio_zone *z;
  
  	if (dev == NULL)

  		return -ENXIO;

  	mutex_lock(&kvm->slots_lock);

  
  	i = dev->nb_zones;

  	while (i) {

  		z = &dev->zone[i - 1];
  
  		/* unregister all zones
  		 * included in (zone->addr, zone->size)
  		 */
  
  		if (zone->addr <= z->addr &&
  		    z->addr + z->size <= zone->addr + zone->size) {
  			dev->nb_zones--;
  			*z = dev->zone[dev->nb_zones];
  		}
  		i--;
  	}

  	mutex_unlock(&kvm->slots_lock);

  
  	return 0;
  }