105f8d40a7
Instead of checking whether we'll wrap around, calculate how many entries are available, and check whether we have enough (just one) for the pending mmio. By itself, this doesn't change anything, but it paves the way for making this function lockless. Signed-off-by: Avi Kivity <avi@redhat.com>
165 lines
3.6 KiB
C
165 lines
3.6 KiB
C
/*
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* KVM coalesced MMIO
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*
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* Copyright (c) 2008 Bull S.A.S.
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*
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* Author: Laurent Vivier <Laurent.Vivier@bull.net>
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*
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*/
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#include "iodev.h"
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#include <linux/kvm_host.h>
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#include <linux/kvm.h>
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#include "coalesced_mmio.h"
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static inline struct kvm_coalesced_mmio_dev *to_mmio(struct kvm_io_device *dev)
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{
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return container_of(dev, struct kvm_coalesced_mmio_dev, dev);
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}
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static int coalesced_mmio_in_range(struct kvm_io_device *this,
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gpa_t addr, int len, int is_write)
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{
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struct kvm_coalesced_mmio_dev *dev = to_mmio(this);
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struct kvm_coalesced_mmio_zone *zone;
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struct kvm_coalesced_mmio_ring *ring;
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unsigned avail;
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int i;
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if (!is_write)
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return 0;
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/* kvm->lock is taken by the caller and must be not released before
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* dev.read/write
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*/
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/* Are we able to batch it ? */
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/* last is the first free entry
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* check if we don't meet the first used entry
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* there is always one unused entry in the buffer
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*/
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ring = dev->kvm->coalesced_mmio_ring;
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avail = (ring->first - ring->last - 1) % KVM_COALESCED_MMIO_MAX;
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if (avail < 1) {
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/* full */
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return 0;
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}
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/* is it in a batchable area ? */
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for (i = 0; i < dev->nb_zones; i++) {
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zone = &dev->zone[i];
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/* (addr,len) is fully included in
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* (zone->addr, zone->size)
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*/
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if (zone->addr <= addr &&
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addr + len <= zone->addr + zone->size)
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return 1;
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}
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return 0;
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}
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static void coalesced_mmio_write(struct kvm_io_device *this,
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gpa_t addr, int len, const void *val)
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{
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struct kvm_coalesced_mmio_dev *dev = to_mmio(this);
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struct kvm_coalesced_mmio_ring *ring = dev->kvm->coalesced_mmio_ring;
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/* kvm->lock must be taken by caller before call to in_range()*/
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/* copy data in first free entry of the ring */
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ring->coalesced_mmio[ring->last].phys_addr = addr;
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ring->coalesced_mmio[ring->last].len = len;
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memcpy(ring->coalesced_mmio[ring->last].data, val, len);
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smp_wmb();
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ring->last = (ring->last + 1) % KVM_COALESCED_MMIO_MAX;
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}
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static void coalesced_mmio_destructor(struct kvm_io_device *this)
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{
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struct kvm_coalesced_mmio_dev *dev = to_mmio(this);
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kfree(dev);
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}
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static const struct kvm_io_device_ops coalesced_mmio_ops = {
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.write = coalesced_mmio_write,
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.in_range = coalesced_mmio_in_range,
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.destructor = coalesced_mmio_destructor,
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};
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int kvm_coalesced_mmio_init(struct kvm *kvm)
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{
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struct kvm_coalesced_mmio_dev *dev;
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dev = kzalloc(sizeof(struct kvm_coalesced_mmio_dev), GFP_KERNEL);
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if (!dev)
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return -ENOMEM;
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kvm_iodevice_init(&dev->dev, &coalesced_mmio_ops);
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dev->kvm = kvm;
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kvm->coalesced_mmio_dev = dev;
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kvm_io_bus_register_dev(&kvm->mmio_bus, &dev->dev);
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return 0;
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}
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int kvm_vm_ioctl_register_coalesced_mmio(struct kvm *kvm,
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struct kvm_coalesced_mmio_zone *zone)
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{
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struct kvm_coalesced_mmio_dev *dev = kvm->coalesced_mmio_dev;
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if (dev == NULL)
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return -EINVAL;
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mutex_lock(&kvm->lock);
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if (dev->nb_zones >= KVM_COALESCED_MMIO_ZONE_MAX) {
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mutex_unlock(&kvm->lock);
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return -ENOBUFS;
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}
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dev->zone[dev->nb_zones] = *zone;
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dev->nb_zones++;
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mutex_unlock(&kvm->lock);
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return 0;
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}
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int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm,
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struct kvm_coalesced_mmio_zone *zone)
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{
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int i;
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struct kvm_coalesced_mmio_dev *dev = kvm->coalesced_mmio_dev;
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struct kvm_coalesced_mmio_zone *z;
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if (dev == NULL)
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return -EINVAL;
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mutex_lock(&kvm->lock);
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i = dev->nb_zones;
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while(i) {
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z = &dev->zone[i - 1];
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/* unregister all zones
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* included in (zone->addr, zone->size)
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*/
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if (zone->addr <= z->addr &&
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z->addr + z->size <= zone->addr + zone->size) {
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dev->nb_zones--;
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*z = dev->zone[dev->nb_zones];
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}
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i--;
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}
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mutex_unlock(&kvm->lock);
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return 0;
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}
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