Merge branch 'kvm-updates/2.6.34' of git://git.kernel.org/pub/scm/virt/kvm/kvm

* 'kvm-updates/2.6.34' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (145 commits)
  KVM: x86: Add KVM_CAP_X86_ROBUST_SINGLESTEP
  KVM: VMX: Update instruction length on intercepted BP
  KVM: Fix emulate_sys[call, enter, exit]()'s fault handling
  KVM: Fix segment descriptor loading
  KVM: Fix load_guest_segment_descriptor() to inject page fault
  KVM: x86 emulator: Forbid modifying CS segment register by mov instruction
  KVM: Convert kvm->requests_lock to raw_spinlock_t
  KVM: Convert i8254/i8259 locks to raw_spinlocks
  KVM: x86 emulator: disallow opcode 82 in 64-bit mode
  KVM: x86 emulator: code style cleanup
  KVM: Plan obsolescence of kernel allocated slots, paravirt mmu
  KVM: x86 emulator: Add LOCK prefix validity checking
  KVM: x86 emulator: Check CPL level during privilege instruction emulation
  KVM: x86 emulator: Fix popf emulation
  KVM: x86 emulator: Check IOPL level during io instruction emulation
  KVM: x86 emulator: fix memory access during x86 emulation
  KVM: x86 emulator: Add Virtual-8086 mode of emulation
  KVM: x86 emulator: Add group9 instruction decoding
  KVM: x86 emulator: Add group8 instruction decoding
  KVM: do not store wqh in irqfd
  ...

Trivial conflicts in Documentation/feature-removal-schedule.txt

9 files changed, 384 insertions, 178 deletions

diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
index daece36c0a5..7f1178f6b83 100644
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig
@@ -12,3 +12,6 @@ config HAVE_KVM_EVENTFD
 
 config KVM_APIC_ARCHITECTURE
        bool
+
+config KVM_MMIO
+       bool
diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c
index f73de631e3e..057e2cca6af 100644
--- a/virt/kvm/assigned-dev.c
+++ b/virt/kvm/assigned-dev.c
@@ -504,12 +504,12 @@ out:
 static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
 				      struct kvm_assigned_pci_dev *assigned_dev)
 {
-	int r = 0;
+	int r = 0, idx;
 	struct kvm_assigned_dev_kernel *match;
 	struct pci_dev *dev;
 
 	mutex_lock(&kvm->lock);
-	down_read(&kvm->slots_lock);
+	idx = srcu_read_lock(&kvm->srcu);
 
 	match = kvm_find_assigned_dev(&kvm->arch.assigned_dev_head,
 				      assigned_dev->assigned_dev_id);
@@ -526,7 +526,8 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
 		r = -ENOMEM;
 		goto out;
 	}
-	dev = pci_get_bus_and_slot(assigned_dev->busnr,
+	dev = pci_get_domain_bus_and_slot(assigned_dev->segnr,
+				   assigned_dev->busnr,
 				   assigned_dev->devfn);
 	if (!dev) {
 		printk(KERN_INFO "%s: host device not found\n", __func__);
@@ -548,6 +549,7 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
 	pci_reset_function(dev);
 
 	match->assigned_dev_id = assigned_dev->assigned_dev_id;
+	match->host_segnr = assigned_dev->segnr;
 	match->host_busnr = assigned_dev->busnr;
 	match->host_devfn = assigned_dev->devfn;
 	match->flags = assigned_dev->flags;
@@ -573,7 +575,7 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
 	}
 
 out:
-	up_read(&kvm->slots_lock);
+	srcu_read_unlock(&kvm->srcu, idx);
 	mutex_unlock(&kvm->lock);
 	return r;
 out_list_del:
@@ -585,7 +587,7 @@ out_put:
 	pci_dev_put(dev);
 out_free:
 	kfree(match);
-	up_read(&kvm->slots_lock);
+	srcu_read_unlock(&kvm->srcu, idx);
 	mutex_unlock(&kvm->lock);
 	return r;
 }
diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c
index 04d69cd7049..5169736377a 100644
--- a/virt/kvm/coalesced_mmio.c
+++ b/virt/kvm/coalesced_mmio.c
@@ -92,41 +92,64 @@ static const struct kvm_io_device_ops coalesced_mmio_ops = {
 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)
-		return -ENOMEM;
+		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;
 
-	ret = kvm_io_bus_register_dev(kvm, &kvm->mmio_bus, &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)
-		kfree(dev);
+		goto out_free_dev;
+
+	return ret;
 
+out_free_dev:
+	kfree(dev);
+out_free_page:
+	__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_zone *zone)
 {
 	struct kvm_coalesced_mmio_dev *dev = kvm->coalesced_mmio_dev;
 
 	if (dev == NULL)
 		return -EINVAL;
 
-	down_write(&kvm->slots_lock);
+	mutex_lock(&kvm->slots_lock);
 	if (dev->nb_zones >= KVM_COALESCED_MMIO_ZONE_MAX) {
-		up_write(&kvm->slots_lock);
+		mutex_unlock(&kvm->slots_lock);
 		return -ENOBUFS;
 	}
 
 	dev->zone[dev->nb_zones] = *zone;
 	dev->nb_zones++;
 
-	up_write(&kvm->slots_lock);
+	mutex_unlock(&kvm->slots_lock);
 	return 0;
 }
 
@@ -140,10 +163,10 @@ int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm,
 	if (dev == NULL)
 		return -EINVAL;
 
-	down_write(&kvm->slots_lock);
+	mutex_lock(&kvm->slots_lock);
 
 	i = dev->nb_zones;
-	while(i) {
+	while (i) {
 		z = &dev->zone[i - 1];
 
 		/* unregister all zones
@@ -158,7 +181,7 @@ int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm,
 		i--;
 	}
 
-	up_write(&kvm->slots_lock);
+	mutex_unlock(&kvm->slots_lock);
 
 	return 0;
 }
diff --git a/virt/kvm/coalesced_mmio.h b/virt/kvm/coalesced_mmio.h
index 4b49f27fa31..8a5959e3535 100644
--- a/virt/kvm/coalesced_mmio.h
+++ b/virt/kvm/coalesced_mmio.h
@@ -1,3 +1,6 @@
+#ifndef __KVM_COALESCED_MMIO_H__
+#define __KVM_COALESCED_MMIO_H__
+
 /*
  * KVM coalesced MMIO
  *
@@ -7,6 +10,8 @@
  *
  */
 
+#ifdef CONFIG_KVM_MMIO
+
 #define KVM_COALESCED_MMIO_ZONE_MAX 100
 
 struct kvm_coalesced_mmio_dev {
@@ -18,7 +23,17 @@ struct kvm_coalesced_mmio_dev {
 };
 
 int kvm_coalesced_mmio_init(struct kvm *kvm);
+void kvm_coalesced_mmio_free(struct kvm *kvm);
 int kvm_vm_ioctl_register_coalesced_mmio(struct kvm *kvm,
                                        struct kvm_coalesced_mmio_zone *zone);
 int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm,
                                          struct kvm_coalesced_mmio_zone *zone);
+
+#else
+
+static inline int kvm_coalesced_mmio_init(struct kvm *kvm) { return 0; }
+static inline void kvm_coalesced_mmio_free(struct kvm *kvm) { }
+
+#endif
+
+#endif
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index a9d3fc6c681..7016319b1ec 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -47,7 +47,6 @@ struct _irqfd {
 	int                       gsi;
 	struct list_head          list;
 	poll_table                pt;
-	wait_queue_head_t        *wqh;
 	wait_queue_t              wait;
 	struct work_struct        inject;
 	struct work_struct        shutdown;
@@ -159,8 +158,6 @@ irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
 			poll_table *pt)
 {
 	struct _irqfd *irqfd = container_of(pt, struct _irqfd, pt);
-
-	irqfd->wqh = wqh;
 	add_wait_queue(wqh, &irqfd->wait);
 }
 
@@ -463,7 +460,7 @@ static int
 kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
 {
 	int                       pio = args->flags & KVM_IOEVENTFD_FLAG_PIO;
-	struct kvm_io_bus        *bus = pio ? &kvm->pio_bus : &kvm->mmio_bus;
+	enum kvm_bus              bus_idx = pio ? KVM_PIO_BUS : KVM_MMIO_BUS;
 	struct _ioeventfd        *p;
 	struct eventfd_ctx       *eventfd;
 	int                       ret;
@@ -508,7 +505,7 @@ kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
 	else
 		p->wildcard = true;
 
-	down_write(&kvm->slots_lock);
+	mutex_lock(&kvm->slots_lock);
 
 	/* Verify that there isnt a match already */
 	if (ioeventfd_check_collision(kvm, p)) {
@@ -518,18 +515,18 @@ kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
 
 	kvm_iodevice_init(&p->dev, &ioeventfd_ops);
 
-	ret = __kvm_io_bus_register_dev(bus, &p->dev);
+	ret = kvm_io_bus_register_dev(kvm, bus_idx, &p->dev);
 	if (ret < 0)
 		goto unlock_fail;
 
 	list_add_tail(&p->list, &kvm->ioeventfds);
 
-	up_write(&kvm->slots_lock);
+	mutex_unlock(&kvm->slots_lock);
 
 	return 0;
 
 unlock_fail:
-	up_write(&kvm->slots_lock);
+	mutex_unlock(&kvm->slots_lock);
 
 fail:
 	kfree(p);
@@ -542,7 +539,7 @@ static int
 kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
 {
 	int                       pio = args->flags & KVM_IOEVENTFD_FLAG_PIO;
-	struct kvm_io_bus        *bus = pio ? &kvm->pio_bus : &kvm->mmio_bus;
+	enum kvm_bus              bus_idx = pio ? KVM_PIO_BUS : KVM_MMIO_BUS;
 	struct _ioeventfd        *p, *tmp;
 	struct eventfd_ctx       *eventfd;
 	int                       ret = -ENOENT;
@@ -551,7 +548,7 @@ kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
 	if (IS_ERR(eventfd))
 		return PTR_ERR(eventfd);
 
-	down_write(&kvm->slots_lock);
+	mutex_lock(&kvm->slots_lock);
 
 	list_for_each_entry_safe(p, tmp, &kvm->ioeventfds, list) {
 		bool wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
@@ -565,13 +562,13 @@ kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
 		if (!p->wildcard && p->datamatch != args->datamatch)
 			continue;
 
-		__kvm_io_bus_unregister_dev(bus, &p->dev);
+		kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev);
 		ioeventfd_release(p);
 		ret = 0;
 		break;
 	}
 
-	up_write(&kvm->slots_lock);
+	mutex_unlock(&kvm->slots_lock);
 
 	eventfd_ctx_put(eventfd);
 
diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
index 38a2d20b89d..3db15a807f8 100644
--- a/virt/kvm/ioapic.c
+++ b/virt/kvm/ioapic.c
@@ -100,6 +100,19 @@ static int ioapic_service(struct kvm_ioapic *ioapic, unsigned int idx)
 	return injected;
 }
 
+static void update_handled_vectors(struct kvm_ioapic *ioapic)
+{
+	DECLARE_BITMAP(handled_vectors, 256);
+	int i;
+
+	memset(handled_vectors, 0, sizeof(handled_vectors));
+	for (i = 0; i < IOAPIC_NUM_PINS; ++i)
+		__set_bit(ioapic->redirtbl[i].fields.vector, handled_vectors);
+	memcpy(ioapic->handled_vectors, handled_vectors,
+	       sizeof(handled_vectors));
+	smp_wmb();
+}
+
 static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val)
 {
 	unsigned index;
@@ -134,6 +147,7 @@ static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val)
 			e->bits |= (u32) val;
 			e->fields.remote_irr = 0;
 		}
+		update_handled_vectors(ioapic);
 		mask_after = e->fields.mask;
 		if (mask_before != mask_after)
 			kvm_fire_mask_notifiers(ioapic->kvm, index, mask_after);
@@ -241,6 +255,9 @@ void kvm_ioapic_update_eoi(struct kvm *kvm, int vector, int trigger_mode)
 {
 	struct kvm_ioapic *ioapic = kvm->arch.vioapic;
 
+	smp_rmb();
+	if (!test_bit(vector, ioapic->handled_vectors))
+		return;
 	mutex_lock(&ioapic->lock);
 	__kvm_ioapic_update_eoi(ioapic, vector, trigger_mode);
 	mutex_unlock(&ioapic->lock);
@@ -352,6 +369,7 @@ void kvm_ioapic_reset(struct kvm_ioapic *ioapic)
 	ioapic->ioregsel = 0;
 	ioapic->irr = 0;
 	ioapic->id = 0;
+	update_handled_vectors(ioapic);
 }
 
 static const struct kvm_io_device_ops ioapic_mmio_ops = {
@@ -372,13 +390,28 @@ int kvm_ioapic_init(struct kvm *kvm)
 	kvm_ioapic_reset(ioapic);
 	kvm_iodevice_init(&ioapic->dev, &ioapic_mmio_ops);
 	ioapic->kvm = kvm;
-	ret = kvm_io_bus_register_dev(kvm, &kvm->mmio_bus, &ioapic->dev);
-	if (ret < 0)
+	mutex_lock(&kvm->slots_lock);
+	ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, &ioapic->dev);
+	mutex_unlock(&kvm->slots_lock);
+	if (ret < 0) {
+		kvm->arch.vioapic = NULL;
 		kfree(ioapic);
+	}
 
 	return ret;
 }
 
+void kvm_ioapic_destroy(struct kvm *kvm)
+{
+	struct kvm_ioapic *ioapic = kvm->arch.vioapic;
+
+	if (ioapic) {
+		kvm_io_bus_unregister_dev(kvm, KVM_MMIO_BUS, &ioapic->dev);
+		kvm->arch.vioapic = NULL;
+		kfree(ioapic);
+	}
+}
+
 int kvm_get_ioapic(struct kvm *kvm, struct kvm_ioapic_state *state)
 {
 	struct kvm_ioapic *ioapic = ioapic_irqchip(kvm);
@@ -399,6 +432,7 @@ int kvm_set_ioapic(struct kvm *kvm, struct kvm_ioapic_state *state)
 
 	mutex_lock(&ioapic->lock);
 	memcpy(ioapic, state, sizeof(struct kvm_ioapic_state));
+	update_handled_vectors(ioapic);
 	mutex_unlock(&ioapic->lock);
 	return 0;
 }
diff --git a/virt/kvm/ioapic.h b/virt/kvm/ioapic.h
index 419c43b667a..8a751b78a43 100644
--- a/virt/kvm/ioapic.h
+++ b/virt/kvm/ioapic.h
@@ -46,6 +46,7 @@ struct kvm_ioapic {
 	struct kvm *kvm;
 	void (*ack_notifier)(void *opaque, int irq);
 	struct mutex lock;
+	DECLARE_BITMAP(handled_vectors, 256);
 };
 
 #ifdef DEBUG
@@ -71,6 +72,7 @@ int kvm_apic_match_dest(struct kvm_vcpu *vcpu, struct kvm_lapic *source,
 int kvm_apic_compare_prio(struct kvm_vcpu *vcpu1, struct kvm_vcpu *vcpu2);
 void kvm_ioapic_update_eoi(struct kvm *kvm, int vector, int trigger_mode);
 int kvm_ioapic_init(struct kvm *kvm);
+void kvm_ioapic_destroy(struct kvm *kvm);
 int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int level);
 void kvm_ioapic_reset(struct kvm_ioapic *ioapic);
 int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c
index 15147583abd..80fd3ad3b2d 100644
--- a/virt/kvm/iommu.c
+++ b/virt/kvm/iommu.c
@@ -32,10 +32,10 @@ static int kvm_iommu_unmap_memslots(struct kvm *kvm);
 static void kvm_iommu_put_pages(struct kvm *kvm,
 				gfn_t base_gfn, unsigned long npages);
 
-int kvm_iommu_map_pages(struct kvm *kvm,
-			gfn_t base_gfn, unsigned long npages)
+int kvm_iommu_map_pages(struct kvm *kvm, struct kvm_memory_slot *slot)
 {
-	gfn_t gfn = base_gfn;
+	gfn_t gfn = slot->base_gfn;
+	unsigned long npages = slot->npages;
 	pfn_t pfn;
 	int i, r = 0;
 	struct iommu_domain *domain = kvm->arch.iommu_domain;
@@ -54,7 +54,7 @@ int kvm_iommu_map_pages(struct kvm *kvm,
 		if (iommu_iova_to_phys(domain, gfn_to_gpa(gfn)))
 			continue;
 
-		pfn = gfn_to_pfn(kvm, gfn);
+		pfn = gfn_to_pfn_memslot(kvm, slot, gfn);
 		r = iommu_map_range(domain,
 				    gfn_to_gpa(gfn),
 				    pfn_to_hpa(pfn),
@@ -69,17 +69,19 @@ int kvm_iommu_map_pages(struct kvm *kvm,
 	return 0;
 
 unmap_pages:
-	kvm_iommu_put_pages(kvm, base_gfn, i);
+	kvm_iommu_put_pages(kvm, slot->base_gfn, i);
 	return r;
 }
 
 static int kvm_iommu_map_memslots(struct kvm *kvm)
 {
 	int i, r = 0;
+	struct kvm_memslots *slots;
+
+	slots = rcu_dereference(kvm->memslots);
 
-	for (i = 0; i < kvm->nmemslots; i++) {
-		r = kvm_iommu_map_pages(kvm, kvm->memslots[i].base_gfn,
-					kvm->memslots[i].npages);
+	for (i = 0; i < slots->nmemslots; i++) {
+		r = kvm_iommu_map_pages(kvm, &slots->memslots[i]);
 		if (r)
 			break;
 	}
@@ -104,7 +106,8 @@ int kvm_assign_device(struct kvm *kvm,
 
 	r = iommu_attach_device(domain, &pdev->dev);
 	if (r) {
-		printk(KERN_ERR "assign device %x:%x.%x failed",
+		printk(KERN_ERR "assign device %x:%x:%x.%x failed",
+			pci_domain_nr(pdev->bus),
 			pdev->bus->number,
 			PCI_SLOT(pdev->devfn),
 			PCI_FUNC(pdev->devfn));
@@ -125,7 +128,8 @@ int kvm_assign_device(struct kvm *kvm,
 			goto out_unmap;
 	}
 
-	printk(KERN_DEBUG "assign device: host bdf = %x:%x:%x\n",
+	printk(KERN_DEBUG "assign device %x:%x:%x.%x\n",
+		assigned_dev->host_segnr,
 		assigned_dev->host_busnr,
 		PCI_SLOT(assigned_dev->host_devfn),
 		PCI_FUNC(assigned_dev->host_devfn));
@@ -152,7 +156,8 @@ int kvm_deassign_device(struct kvm *kvm,
 
 	iommu_detach_device(domain, &pdev->dev);
 
-	printk(KERN_DEBUG "deassign device: host bdf = %x:%x:%x\n",
+	printk(KERN_DEBUG "deassign device %x:%x:%x.%x\n",
+		assigned_dev->host_segnr,
 		assigned_dev->host_busnr,
 		PCI_SLOT(assigned_dev->host_devfn),
 		PCI_FUNC(assigned_dev->host_devfn));
@@ -210,10 +215,13 @@ static void kvm_iommu_put_pages(struct kvm *kvm,
 static int kvm_iommu_unmap_memslots(struct kvm *kvm)
 {
 	int i;
+	struct kvm_memslots *slots;
+
+	slots = rcu_dereference(kvm->memslots);
 
-	for (i = 0; i < kvm->nmemslots; i++) {
-		kvm_iommu_put_pages(kvm, kvm->memslots[i].base_gfn,
-				    kvm->memslots[i].npages);
+	for (i = 0; i < slots->nmemslots; i++) {
+		kvm_iommu_put_pages(kvm, slots->memslots[i].base_gfn,
+				    slots->memslots[i].npages);
 	}
 
 	return 0;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index a944be392d6..548f9253c19 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -44,6 +44,8 @@
 #include <linux/bitops.h>
 #include <linux/spinlock.h>
 #include <linux/compat.h>
+#include <linux/srcu.h>
+#include <linux/hugetlb.h>
 
 #include <asm/processor.h>
 #include <asm/io.h>
@@ -51,9 +53,7 @@
 #include <asm/pgtable.h>
 #include <asm-generic/bitops/le.h>
 
-#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
 #include "coalesced_mmio.h"
-#endif
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/kvm.h>
@@ -86,6 +86,8 @@ static long kvm_vcpu_ioctl(struct file *file, unsigned int ioctl,
 static int hardware_enable_all(void);
 static void hardware_disable_all(void);
 
+static void kvm_io_bus_destroy(struct kvm_io_bus *bus);
+
 static bool kvm_rebooting;
 
 static bool largepages_enabled = true;
@@ -136,7 +138,7 @@ static bool make_all_cpus_request(struct kvm *kvm, unsigned int req)
 
 	zalloc_cpumask_var(&cpus, GFP_ATOMIC);
 
-	spin_lock(&kvm->requests_lock);
+	raw_spin_lock(&kvm->requests_lock);
 	me = smp_processor_id();
 	kvm_for_each_vcpu(i, vcpu, kvm) {
 		if (test_and_set_bit(req, &vcpu->requests))
@@ -151,7 +153,7 @@ static bool make_all_cpus_request(struct kvm *kvm, unsigned int req)
 		smp_call_function_many(cpus, ack_flush, NULL, 1);
 	else
 		called = false;
-	spin_unlock(&kvm->requests_lock);
+	raw_spin_unlock(&kvm->requests_lock);
 	free_cpumask_var(cpus);
 	return called;
 }
@@ -215,7 +217,7 @@ static void kvm_mmu_notifier_invalidate_page(struct mmu_notifier *mn,
 					     unsigned long address)
 {
 	struct kvm *kvm = mmu_notifier_to_kvm(mn);
-	int need_tlb_flush;
+	int need_tlb_flush, idx;
 
 	/*
 	 * When ->invalidate_page runs, the linux pte has been zapped
@@ -235,10 +237,12 @@ static void kvm_mmu_notifier_invalidate_page(struct mmu_notifier *mn,
 	 * pte after kvm_unmap_hva returned, without noticing the page
 	 * is going to be freed.
 	 */
+	idx = srcu_read_lock(&kvm->srcu);
 	spin_lock(&kvm->mmu_lock);
 	kvm->mmu_notifier_seq++;
 	need_tlb_flush = kvm_unmap_hva(kvm, address);
 	spin_unlock(&kvm->mmu_lock);
+	srcu_read_unlock(&kvm->srcu, idx);
 
 	/* we've to flush the tlb before the pages can be freed */
 	if (need_tlb_flush)
@@ -252,11 +256,14 @@ static void kvm_mmu_notifier_change_pte(struct mmu_notifier *mn,
 					pte_t pte)
 {
 	struct kvm *kvm = mmu_notifier_to_kvm(mn);
+	int idx;
 
+	idx = srcu_read_lock(&kvm->srcu);
 	spin_lock(&kvm->mmu_lock);
 	kvm->mmu_notifier_seq++;
 	kvm_set_spte_hva(kvm, address, pte);
 	spin_unlock(&kvm->mmu_lock);
+	srcu_read_unlock(&kvm->srcu, idx);
 }
 
 static void kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
@@ -265,8 +272,9 @@ static void kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
 						    unsigned long end)
 {
 	struct kvm *kvm = mmu_notifier_to_kvm(mn);
-	int need_tlb_flush = 0;
+	int need_tlb_flush = 0, idx;
 
+	idx = srcu_read_lock(&kvm->srcu);
 	spin_lock(&kvm->mmu_lock);
 	/*
 	 * The count increase must become visible at unlock time as no
@@ -277,6 +285,7 @@ static void kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
 	for (; start < end; start += PAGE_SIZE)
 		need_tlb_flush |= kvm_unmap_hva(kvm, start);
 	spin_unlock(&kvm->mmu_lock);
+	srcu_read_unlock(&kvm->srcu, idx);
 
 	/* we've to flush the tlb before the pages can be freed */
 	if (need_tlb_flush)
@@ -314,11 +323,13 @@ static int kvm_mmu_notifier_clear_flush_young(struct mmu_notifier *mn,
 					      unsigned long address)
 {
 	struct kvm *kvm = mmu_notifier_to_kvm(mn);
-	int young;
+	int young, idx;
 
+	idx = srcu_read_lock(&kvm->srcu);
 	spin_lock(&kvm->mmu_lock);
 	young = kvm_age_hva(kvm, address);
 	spin_unlock(&kvm->mmu_lock);
+	srcu_read_unlock(&kvm->srcu, idx);
 
 	if (young)
 		kvm_flush_remote_tlbs(kvm);
@@ -341,15 +352,26 @@ static const struct mmu_notifier_ops kvm_mmu_notifier_ops = {
 	.change_pte		= kvm_mmu_notifier_change_pte,
 	.release		= kvm_mmu_notifier_release,
 };
+
+static int kvm_init_mmu_notifier(struct kvm *kvm)
+{
+	kvm->mmu_notifier.ops = &kvm_mmu_notifier_ops;
+	return mmu_notifier_register(&kvm->mmu_notifier, current->mm);
+}
+
+#else  /* !(CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER) */
+
+static int kvm_init_mmu_notifier(struct kvm *kvm)
+{
+	return 0;
+}
+
 #endif /* CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER */
 
 static struct kvm *kvm_create_vm(void)
 {
-	int r = 0;
+	int r = 0, i;
 	struct kvm *kvm = kvm_arch_create_vm();
-#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
-	struct page *page;
-#endif
 
 	if (IS_ERR(kvm))
 		goto out;
@@ -363,39 +385,35 @@ static struct kvm *kvm_create_vm(void)
 	INIT_HLIST_HEAD(&kvm->irq_ack_notifier_list);
 #endif
 
-#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
-	page = alloc_page(GFP_KERNEL | __GFP_ZERO);
-	if (!page) {
-		r = -ENOMEM;
+	r = -ENOMEM;
+	kvm->memslots = kzalloc(sizeof(struct kvm_memslots), GFP_KERNEL);
+	if (!kvm->memslots)
 		goto out_err;
-	}
-	kvm->coalesced_mmio_ring =
-			(struct kvm_coalesced_mmio_ring *)page_address(page);
-#endif
-
-#if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
-	{
-		kvm->mmu_notifier.ops = &kvm_mmu_notifier_ops;
-		r = mmu_notifier_register(&kvm->mmu_notifier, current->mm);
-		if (r) {
-#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
-			put_page(page);
-#endif
+	if (init_srcu_struct(&kvm->srcu))
+		goto out_err;
+	for (i = 0; i < KVM_NR_BUSES; i++) {
+		kvm->buses[i] = kzalloc(sizeof(struct kvm_io_bus),
+					GFP_KERNEL);
+		if (!kvm->buses[i]) {
+			cleanup_srcu_struct(&kvm->srcu);
 			goto out_err;
 		}
 	}
-#endif
+
+	r = kvm_init_mmu_notifier(kvm);
+	if (r) {
+		cleanup_srcu_struct(&kvm->srcu);
+		goto out_err;
+	}
 
 	kvm->mm = current->mm;
 	atomic_inc(&kvm->mm->mm_count);
 	spin_lock_init(&kvm->mmu_lock);
-	spin_lock_init(&kvm->requests_lock);
-	kvm_io_bus_init(&kvm->pio_bus);
+	raw_spin_lock_init(&kvm->requests_lock);
 	kvm_eventfd_init(kvm);
 	mutex_init(&kvm->lock);
 	mutex_init(&kvm->irq_lock);
-	kvm_io_bus_init(&kvm->mmio_bus);
-	init_rwsem(&kvm->slots_lock);
+	mutex_init(&kvm->slots_lock);
 	atomic_set(&kvm->users_count, 1);
 	spin_lock(&kvm_lock);
 	list_add(&kvm->vm_list, &vm_list);
@@ -406,12 +424,12 @@ static struct kvm *kvm_create_vm(void)
 out:
 	return kvm;
 
-#if defined(KVM_COALESCED_MMIO_PAGE_OFFSET) || \
-    (defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER))
 out_err:
 	hardware_disable_all();
-#endif
 out_err_nodisable:
+	for (i = 0; i < KVM_NR_BUSES; i++)
+		kfree(kvm->buses[i]);
+	kfree(kvm->memslots);
 	kfree(kvm);
 	return ERR_PTR(r);
 }
@@ -446,13 +464,17 @@ static void kvm_free_physmem_slot(struct kvm_memory_slot *free,
 void kvm_free_physmem(struct kvm *kvm)
 {
 	int i;
+	struct kvm_memslots *slots = kvm->memslots;
+
+	for (i = 0; i < slots->nmemslots; ++i)
+		kvm_free_physmem_slot(&slots->memslots[i], NULL);
 
-	for (i = 0; i < kvm->nmemslots; ++i)
-		kvm_free_physmem_slot(&kvm->memslots[i], NULL);
+	kfree(kvm->memslots);
 }
 
 static void kvm_destroy_vm(struct kvm *kvm)
 {
+	int i;
 	struct mm_struct *mm = kvm->mm;
 
 	kvm_arch_sync_events(kvm);
@@ -460,12 +482,9 @@ static void kvm_destroy_vm(struct kvm *kvm)
 	list_del(&kvm->vm_list);
 	spin_unlock(&kvm_lock);
 	kvm_free_irq_routing(kvm);
-	kvm_io_bus_destroy(&kvm->pio_bus);
-	kvm_io_bus_destroy(&kvm->mmio_bus);
-#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
-	if (kvm->coalesced_mmio_ring != NULL)
-		free_page((unsigned long)kvm->coalesced_mmio_ring);
-#endif
+	for (i = 0; i < KVM_NR_BUSES; i++)
+		kvm_io_bus_destroy(kvm->buses[i]);
+	kvm_coalesced_mmio_free(kvm);
 #if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
 	mmu_notifier_unregister(&kvm->mmu_notifier, kvm->mm);
 #else
@@ -512,12 +531,13 @@ int __kvm_set_memory_region(struct kvm *kvm,
 			    struct kvm_userspace_memory_region *mem,
 			    int user_alloc)
 {
-	int r;
+	int r, flush_shadow = 0;
 	gfn_t base_gfn;
 	unsigned long npages;
 	unsigned long i;
 	struct kvm_memory_slot *memslot;
 	struct kvm_memory_slot old, new;
+	struct kvm_memslots *slots, *old_memslots;
 
 	r = -EINVAL;
 	/* General sanity checks */
@@ -532,7 +552,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	if (mem->guest_phys_addr + mem->memory_size < mem->guest_phys_addr)
 		goto out;
 
-	memslot = &kvm->memslots[mem->slot];
+	memslot = &kvm->memslots->memslots[mem->slot];
 	base_gfn = mem->guest_phys_addr >> PAGE_SHIFT;
 	npages = mem->memory_size >> PAGE_SHIFT;
 
@@ -553,7 +573,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	/* Check for overlaps */
 	r = -EEXIST;
 	for (i = 0; i < KVM_MEMORY_SLOTS; ++i) {
-		struct kvm_memory_slot *s = &kvm->memslots[i];
+		struct kvm_memory_slot *s = &kvm->memslots->memslots[i];
 
 		if (s == memslot || !s->npages)
 			continue;
@@ -579,15 +599,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
 		memset(new.rmap, 0, npages * sizeof(*new.rmap));
 
 		new.user_alloc = user_alloc;
-		/*
-		 * hva_to_rmmap() serialzies with the mmu_lock and to be
-		 * safe it has to ignore memslots with !user_alloc &&
-		 * !userspace_addr.
-		 */
-		if (user_alloc)
-			new.userspace_addr = mem->userspace_addr;
-		else
-			new.userspace_addr = 0;
+		new.userspace_addr = mem->userspace_addr;
 	}
 	if (!npages)
 		goto skip_lpage;
@@ -642,8 +654,9 @@ skip_lpage:
 		if (!new.dirty_bitmap)
 			goto out_free;
 		memset(new.dirty_bitmap, 0, dirty_bytes);
+		/* destroy any largepage mappings for dirty tracking */
 		if (old.npages)
-			kvm_arch_flush_shadow(kvm);
+			flush_shadow = 1;
 	}
 #else  /* not defined CONFIG_S390 */
 	new.user_alloc = user_alloc;
@@ -651,36 +664,72 @@ skip_lpage:
 		new.userspace_addr = mem->userspace_addr;
 #endif /* not defined CONFIG_S390 */
 
-	if (!npages)
+	if (!npages) {
+		r = -ENOMEM;
+		slots = kzalloc(sizeof(struct kvm_memslots), GFP_KERNEL);
+		if (!slots)
+			goto out_free;
+		memcpy(slots, kvm->memslots, sizeof(struct kvm_memslots));
+		if (mem->slot >= slots->nmemslots)
+			slots->nmemslots = mem->slot + 1;
+		slots->memslots[mem->slot].flags |= KVM_MEMSLOT_INVALID;
+
+		old_memslots = kvm->memslots;
+		rcu_assign_pointer(kvm->memslots, slots);
+		synchronize_srcu_expedited(&kvm->srcu);
+		/* From this point no new shadow pages pointing to a deleted
+		 * memslot will be created.
+		 *
+		 * validation of sp->gfn happens in:
+		 * 	- gfn_to_hva (kvm_read_guest, gfn_to_pfn)
+		 * 	- kvm_is_visible_gfn (mmu_check_roots)
+		 */
 		kvm_arch_flush_shadow(kvm);
+		kfree(old_memslots);
+	}
 
-	spin_lock(&kvm->mmu_lock);
-	if (mem->slot >= kvm->nmemslots)
-		kvm->nmemslots = mem->slot + 1;
-
-	*memslot = new;
-	spin_unlock(&kvm->mmu_lock);
-
-	r = kvm_arch_set_memory_region(kvm, mem, old, user_alloc);
-	if (r) {
-		spin_lock(&kvm->mmu_lock);
-		*memslot = old;
-		spin_unlock(&kvm->mmu_lock);
+	r = kvm_arch_prepare_memory_region(kvm, &new, old, mem, user_alloc);
+	if (r)
 		goto out_free;
-	}
 
-	kvm_free_physmem_slot(&old, npages ? &new : NULL);
-	/* Slot deletion case: we have to update the current slot */
-	spin_lock(&kvm->mmu_lock);
-	if (!npages)
-		*memslot = old;
-	spin_unlock(&kvm->mmu_lock);
 #ifdef CONFIG_DMAR
 	/* map the pages in iommu page table */
-	r = kvm_iommu_map_pages(kvm, base_gfn, npages);
-	if (r)
-		goto out;
+	if (npages) {
+		r = kvm_iommu_map_pages(kvm, &new);
+		if (r)
+			goto out_free;
+	}
 #endif
+
+	r = -ENOMEM;
+	slots = kzalloc(sizeof(struct kvm_memslots), GFP_KERNEL);
+	if (!slots)
+		goto out_free;
+	memcpy(slots, kvm->memslots, sizeof(struct kvm_memslots));
+	if (mem->slot >= slots->nmemslots)
+		slots->nmemslots = mem->slot + 1;
+
+	/* actual memory is freed via old in kvm_free_physmem_slot below */
+	if (!npages) {
+		new.rmap = NULL;
+		new.dirty_bitmap = NULL;
+		for (i = 0; i < KVM_NR_PAGE_SIZES - 1; ++i)
+			new.lpage_info[i] = NULL;
+	}
+
+	slots->memslots[mem->slot] = new;
+	old_memslots = kvm->memslots;
+	rcu_assign_pointer(kvm->memslots, slots);
+	synchronize_srcu_expedited(&kvm->srcu);
+
+	kvm_arch_commit_memory_region(kvm, mem, old, user_alloc);
+
+	kvm_free_physmem_slot(&old, &new);
+	kfree(old_memslots);
+
+	if (flush_shadow)
+		kvm_arch_flush_shadow(kvm);
+
 	return 0;
 
 out_free:
@@ -697,9 +746,9 @@ int kvm_set_memory_region(struct kvm *kvm,
 {
 	int r;
 
-	down_write(&kvm->slots_lock);
+	mutex_lock(&kvm->slots_lock);
 	r = __kvm_set_memory_region(kvm, mem, user_alloc);
-	up_write(&kvm->slots_lock);
+	mutex_unlock(&kvm->slots_lock);
 	return r;
 }
 EXPORT_SYMBOL_GPL(kvm_set_memory_region);
@@ -726,7 +775,7 @@ int kvm_get_dirty_log(struct kvm *kvm,
 	if (log->slot >= KVM_MEMORY_SLOTS)
 		goto out;
 
-	memslot = &kvm->memslots[log->slot];
+	memslot = &kvm->memslots->memslots[log->slot];
 	r = -ENOENT;
 	if (!memslot->dirty_bitmap)
 		goto out;
@@ -780,9 +829,10 @@ EXPORT_SYMBOL_GPL(kvm_is_error_hva);
 struct kvm_memory_slot *gfn_to_memslot_unaliased(struct kvm *kvm, gfn_t gfn)
 {
 	int i;
+	struct kvm_memslots *slots = rcu_dereference(kvm->memslots);
 
-	for (i = 0; i < kvm->nmemslots; ++i) {
-		struct kvm_memory_slot *memslot = &kvm->memslots[i];
+	for (i = 0; i < slots->nmemslots; ++i) {
+		struct kvm_memory_slot *memslot = &slots->memslots[i];
 
 		if (gfn >= memslot->base_gfn
 		    && gfn < memslot->base_gfn + memslot->npages)
@@ -801,10 +851,14 @@ struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn)
 int kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn)
 {
 	int i;
+	struct kvm_memslots *slots = rcu_dereference(kvm->memslots);
 
-	gfn = unalias_gfn(kvm, gfn);
+	gfn = unalias_gfn_instantiation(kvm, gfn);
 	for (i = 0; i < KVM_MEMORY_SLOTS; ++i) {
-		struct kvm_memory_slot *memslot = &kvm->memslots[i];
+		struct kvm_memory_slot *memslot = &slots->memslots[i];
+
+		if (memslot->flags & KVM_MEMSLOT_INVALID)
+			continue;
 
 		if (gfn >= memslot->base_gfn
 		    && gfn < memslot->base_gfn + memslot->npages)
@@ -814,33 +868,68 @@ int kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn)
 }
 EXPORT_SYMBOL_GPL(kvm_is_visible_gfn);
 
+unsigned long kvm_host_page_size(struct kvm *kvm, gfn_t gfn)
+{
+	struct vm_area_struct *vma;
+	unsigned long addr, size;
+
+	size = PAGE_SIZE;
+
+	addr = gfn_to_hva(kvm, gfn);
+	if (kvm_is_error_hva(addr))
+		return PAGE_SIZE;
+
+	down_read(&current->mm->mmap_sem);
+	vma = find_vma(current->mm, addr);
+	if (!vma)
+		goto out;
+
+	size = vma_kernel_pagesize(vma);
+
+out:
+	up_read(&current->mm->mmap_sem);
+
+	return size;
+}
+
+int memslot_id(struct kvm *kvm, gfn_t gfn)
+{
+	int i;
+	struct kvm_memslots *slots = rcu_dereference(kvm->memslots);
+	struct kvm_memory_slot *memslot = NULL;
+
+	gfn = unalias_gfn(kvm, gfn);
+	for (i = 0; i < slots->nmemslots; ++i) {
+		memslot = &slots->memslots[i];
+
+		if (gfn >= memslot->base_gfn
+		    && gfn < memslot->base_gfn + memslot->npages)
+			break;
+	}
+
+	return memslot - slots->memslots;
+}
+
 unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn)
 {
 	struct kvm_memory_slot *slot;
 
-	gfn = unalias_gfn(kvm, gfn);
+	gfn = unalias_gfn_instantiation(kvm, gfn);
 	slot = gfn_to_memslot_unaliased(kvm, gfn);
-	if (!slot)
+	if (!slot || slot->flags & KVM_MEMSLOT_INVALID)
 		return bad_hva();
 	return (slot->userspace_addr + (gfn - slot->base_gfn) * PAGE_SIZE);
 }
 EXPORT_SYMBOL_GPL(gfn_to_hva);
 
-pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
+static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr)
 {
 	struct page *page[1];
-	unsigned long addr;
 	int npages;
 	pfn_t pfn;
 
 	might_sleep();
 
-	addr = gfn_to_hva(kvm, gfn);
-	if (kvm_is_error_hva(addr)) {
-		get_page(bad_page);
-		return page_to_pfn(bad_page);
-	}
-
 	npages = get_user_pages_fast(addr, 1, 1, page);
 
 	if (unlikely(npages != 1)) {
@@ -865,8 +954,32 @@ pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
 	return pfn;
 }
 
+pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
+{
+	unsigned long addr;
+
+	addr = gfn_to_hva(kvm, gfn);
+	if (kvm_is_error_hva(addr)) {
+		get_page(bad_page);
+		return page_to_pfn(bad_page);
+	}
+
+	return hva_to_pfn(kvm, addr);
+}
 EXPORT_SYMBOL_GPL(gfn_to_pfn);
 
+static unsigned long gfn_to_hva_memslot(struct kvm_memory_slot *slot, gfn_t gfn)
+{
+	return (slot->userspace_addr + (gfn - slot->base_gfn) * PAGE_SIZE);
+}
+
+pfn_t gfn_to_pfn_memslot(struct kvm *kvm,
+			 struct kvm_memory_slot *slot, gfn_t gfn)
+{
+	unsigned long addr = gfn_to_hva_memslot(slot, gfn);
+	return hva_to_pfn(kvm, addr);
+}
+
 struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
 {
 	pfn_t pfn;
@@ -1854,12 +1967,7 @@ static struct notifier_block kvm_reboot_notifier = {
 	.priority = 0,
 };
 
-void kvm_io_bus_init(struct kvm_io_bus *bus)
-{
-	memset(bus, 0, sizeof(*bus));
-}
-
-void kvm_io_bus_destroy(struct kvm_io_bus *bus)
+static void kvm_io_bus_destroy(struct kvm_io_bus *bus)
 {
 	int i;
 
@@ -1868,13 +1976,15 @@ void kvm_io_bus_destroy(struct kvm_io_bus *bus)
 
 		kvm_iodevice_destructor(pos);
 	}
+	kfree(bus);
 }
 
 /* kvm_io_bus_write - called under kvm->slots_lock */
-int kvm_io_bus_write(struct kvm_io_bus *bus, gpa_t addr,
+int kvm_io_bus_write(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
 		     int len, const void *val)
 {
 	int i;
+	struct kvm_io_bus *bus = rcu_dereference(kvm->buses[bus_idx]);
 	for (i = 0; i < bus->dev_count; i++)
 		if (!kvm_iodevice_write(bus->devs[i], addr, len, val))
 			return 0;
@@ -1882,59 +1992,71 @@ int kvm_io_bus_write(struct kvm_io_bus *bus, gpa_t addr,
 }
 
 /* kvm_io_bus_read - called under kvm->slots_lock */
-int kvm_io_bus_read(struct kvm_io_bus *bus, gpa_t addr, int len, void *val)
+int kvm_io_bus_read(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
+		    int len, void *val)
 {
 	int i;
+	struct kvm_io_bus *bus = rcu_dereference(kvm->buses[bus_idx]);
+
 	for (i = 0; i < bus->dev_count; i++)
 		if (!kvm_iodevice_read(bus->devs[i], addr, len, val))
 			return 0;
 	return -EOPNOTSUPP;
 }
 
-int kvm_io_bus_register_dev(struct kvm *kvm, struct kvm_io_bus *bus,
-			     struct kvm_io_device *dev)
+/* Caller must hold slots_lock. */
+int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx,
+			    struct kvm_io_device *dev)
 {
-	int ret;
-
-	down_write(&kvm->slots_lock);
-	ret = __kvm_io_bus_register_dev(bus, dev);
-	up_write(&kvm->slots_lock);
+	struct kvm_io_bus *new_bus, *bus;
 
-	return ret;
-}
-
-/* An unlocked version. Caller must have write lock on slots_lock. */
-int __kvm_io_bus_register_dev(struct kvm_io_bus *bus,
-			      struct kvm_io_device *dev)
-{
+	bus = kvm->buses[bus_idx];
 	if (bus->dev_count > NR_IOBUS_DEVS-1)
 		return -ENOSPC;
 
-	bus->devs[bus->dev_count++] = dev;
+	new_bus = kzalloc(sizeof(struct kvm_io_bus), GFP_KERNEL);
+	if (!new_bus)
+		return -ENOMEM;
+	memcpy(new_bus, bus, sizeof(struct kvm_io_bus));
+	new_bus->devs[new_bus->dev_count++] = dev;
+	rcu_assign_pointer(kvm->buses[bus_idx], new_bus);
+	synchronize_srcu_expedited(&kvm->srcu);
+	kfree(bus);
 
 	return 0;
 }
 
-void kvm_io_bus_unregister_dev(struct kvm *kvm,
-			       struct kvm_io_bus *bus,
-			       struct kvm_io_device *dev)
+/* Caller must hold slots_lock. */
+int kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx,
+			      struct kvm_io_device *dev)
 {
-	down_write(&kvm->slots_lock);
-	__kvm_io_bus_unregister_dev(bus, dev);
-	up_write(&kvm->slots_lock);
-}
+	int i, r;
+	struct kvm_io_bus *new_bus, *bus;
 
-/* An unlocked version. Caller must have write lock on slots_lock. */
-void __kvm_io_bus_unregister_dev(struct kvm_io_bus *bus,
-				 struct kvm_io_device *dev)
-{
-	int i;
+	new_bus = kzalloc(sizeof(struct kvm_io_bus), GFP_KERNEL);
+	if (!new_bus)
+		return -ENOMEM;
 
-	for (i = 0; i < bus->dev_count; i++)
-		if (bus->devs[i] == dev) {
-			bus->devs[i] = bus->devs[--bus->dev_count];
+	bus = kvm->buses[bus_idx];
+	memcpy(new_bus, bus, sizeof(struct kvm_io_bus));
+
+	r = -ENOENT;
+	for (i = 0; i < new_bus->dev_count; i++)
+		if (new_bus->devs[i] == dev) {
+			r = 0;
+			new_bus->devs[i] = new_bus->devs[--new_bus->dev_count];
 			break;
 		}
+
+	if (r) {
+		kfree(new_bus);
+		return r;
+	}
+
+	rcu_assign_pointer(kvm->buses[bus_idx], new_bus);
+	synchronize_srcu_expedited(&kvm->srcu);
+	kfree(bus);
+	return r;
 }
 
 static struct notifier_block kvm_cpu_notifier = {