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-rw-r--r--virt/kvm/coalesced_mmio.c211
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..ce6f3b916
--- /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 | __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;
+}