diff options
Diffstat (limited to 'virt/kvm/coalesced_mmio.c')
| -rw-r--r-- | virt/kvm/coalesced_mmio.c | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c new file mode 100644 index 00000000..88b2fe3d --- /dev/null +++ b/virt/kvm/coalesced_mmio.c @@ -0,0 +1,186 @@ +/* + * 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) +{ + /* is it in a batchable area ? + * (addr,len) is fully included in + * (zone->addr, zone->size) + */ + if (len < 0) + return 0; + if (addr + len < addr) + return 0; + if (addr < dev->zone.addr) + return 0; + if (addr + len > dev->zone.addr + dev->zone.size) + return 0; + return 1; +} + +static int coalesced_mmio_has_room(struct kvm_coalesced_mmio_dev *dev) +{ + struct kvm_coalesced_mmio_ring *ring; + unsigned avail; + + /* 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 == 0) { + /* full */ + return 0; + } + + return 1; +} + +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->kvm->ring_lock); + + if (!coalesced_mmio_has_room(dev)) { + spin_unlock(&dev->kvm->ring_lock); + return -EOPNOTSUPP; + } + + /* 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->kvm->ring_lock); + return 0; +} + +static void coalesced_mmio_destructor(struct kvm_io_device *this) +{ + struct kvm_coalesced_mmio_dev *dev = to_mmio(this); + + list_del(&dev->list); + + 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 page *page; + int ret; + + ret = -ENOMEM; + page = alloc_page(GFP_KERNEL | __GFP_ZERO); + if (!page) + goto out_err; + + ret = 0; + kvm->coalesced_mmio_ring = page_address(page); + + /* + * We're using this spinlock to sync access to the coalesced ring. + * The list doesn't need it's own lock since device registration and + * unregistration should only happen when kvm->slots_lock is held. + */ + spin_lock_init(&kvm->ring_lock); + INIT_LIST_HEAD(&kvm->coalesced_zones); + +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) +{ + int ret; + struct kvm_coalesced_mmio_dev *dev; + + dev = kzalloc(sizeof(struct kvm_coalesced_mmio_dev), GFP_KERNEL); + if (!dev) + return -ENOMEM; + + kvm_iodevice_init(&dev->dev, &coalesced_mmio_ops); + dev->kvm = kvm; + dev->zone = *zone; + + mutex_lock(&kvm->slots_lock); + ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, zone->addr, + zone->size, &dev->dev); + if (ret < 0) + goto out_free_dev; + list_add_tail(&dev->list, &kvm->coalesced_zones); + mutex_unlock(&kvm->slots_lock); + + return ret; + +out_free_dev: + mutex_unlock(&kvm->slots_lock); + + kfree(dev); + + if (dev == NULL) + return -ENXIO; + + return 0; +} + +int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm, + struct kvm_coalesced_mmio_zone *zone) +{ + struct kvm_coalesced_mmio_dev *dev, *tmp; + + mutex_lock(&kvm->slots_lock); + + list_for_each_entry_safe(dev, tmp, &kvm->coalesced_zones, list) + if (coalesced_mmio_in_range(dev, zone->addr, zone->size)) { + kvm_io_bus_unregister_dev(kvm, KVM_MMIO_BUS, &dev->dev); + kvm_iodevice_destructor(&dev->dev); + } + + mutex_unlock(&kvm->slots_lock); + + return 0; +} |