diff options
Diffstat (limited to 'virt/kvm/coalesced_mmio.c')
| -rw-r--r-- | virt/kvm/coalesced_mmio.c | 211 |
1 files changed, 211 insertions, 0 deletions
diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c new file mode 100644 index 000000000..5ef88f5a0 --- /dev/null +++ b/virt/kvm/coalesced_mmio.c @@ -0,0 +1,211 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * 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 <kvm/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, u32 last) +{ + 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 - last - 1) % KVM_COALESCED_MMIO_MAX; + if (avail == 0) { + /* full */ + return 0; + } + + return 1; +} + +static int coalesced_mmio_write(struct kvm_vcpu *vcpu, + 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; + __u32 insert; + + if (!coalesced_mmio_in_range(dev, addr, len)) + return -EOPNOTSUPP; + + spin_lock(&dev->kvm->ring_lock); + + insert = READ_ONCE(ring->last); + if (!coalesced_mmio_has_room(dev, insert) || + insert >= KVM_COALESCED_MMIO_MAX) { + spin_unlock(&dev->kvm->ring_lock); + return -EOPNOTSUPP; + } + + /* copy data in first free entry of the ring */ + + ring->coalesced_mmio[insert].phys_addr = addr; + ring->coalesced_mmio[insert].len = len; + memcpy(ring->coalesced_mmio[insert].data, val, len); + ring->coalesced_mmio[insert].pio = dev->zone.pio; + smp_wmb(); + ring->last = (insert + 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; + + page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO); + if (!page) + return -ENOMEM; + + kvm->coalesced_mmio_ring = page_address(page); + + /* + * We're using this spinlock to sync access to the coalesced ring. + * The list doesn't need its 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); + + return 0; +} + +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; + + if (zone->pio != 1 && zone->pio != 0) + return -EINVAL; + + dev = kzalloc(sizeof(struct kvm_coalesced_mmio_dev), + GFP_KERNEL_ACCOUNT); + 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, + zone->pio ? KVM_PIO_BUS : 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 0; + +out_free_dev: + mutex_unlock(&kvm->slots_lock); + kfree(dev); + + return ret; +} + +int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm, + struct kvm_coalesced_mmio_zone *zone) +{ + struct kvm_coalesced_mmio_dev *dev, *tmp; + int r; + + if (zone->pio != 1 && zone->pio != 0) + return -EINVAL; + + mutex_lock(&kvm->slots_lock); + + list_for_each_entry_safe(dev, tmp, &kvm->coalesced_zones, list) { + if (zone->pio == dev->zone.pio && + coalesced_mmio_in_range(dev, zone->addr, zone->size)) { + r = kvm_io_bus_unregister_dev(kvm, + zone->pio ? KVM_PIO_BUS : KVM_MMIO_BUS, &dev->dev); + + kvm_iodevice_destructor(&dev->dev); + + /* + * On failure, unregister destroys all devices on the + * bus _except_ the target device, i.e. coalesced_zones + * has been modified. Bail after destroying the target + * device, there's no need to restart the walk as there + * aren't any zones left. + */ + if (r) + break; + } + } + + mutex_unlock(&kvm->slots_lock); + + /* + * Ignore the result of kvm_io_bus_unregister_dev(), from userspace's + * perspective, the coalesced MMIO is most definitely unregistered. + */ + return 0; +} |