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Subject[PATCH 34/40] KVM: convert io_bus to SRCU
Date
From: Marcelo Tosatti <mtosatti@redhat.com>

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
---
arch/ia64/kvm/kvm-ia64.c | 4 +-
arch/x86/kvm/i8254.c | 6 +-
arch/x86/kvm/i8259.c | 4 +-
arch/x86/kvm/x86.c | 13 +++---
include/linux/kvm_host.h | 27 ++++++------
virt/kvm/coalesced_mmio.c | 4 +-
virt/kvm/eventfd.c | 8 ++--
virt/kvm/ioapic.c | 4 +-
virt/kvm/kvm_main.c | 106 ++++++++++++++++++++++++++------------------
9 files changed, 101 insertions(+), 75 deletions(-)
diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index b2e4d16..d0ad538 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -241,10 +241,10 @@ static int handle_mmio(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
return 0;
mmio:
if (p->dir)
- r = kvm_io_bus_read(&vcpu->kvm->mmio_bus, p->addr,
+ r = kvm_io_bus_read(vcpu->kvm, KVM_MMIO_BUS, p->addr,
p->size, &p->data);
else
- r = kvm_io_bus_write(&vcpu->kvm->mmio_bus, p->addr,
+ r = kvm_io_bus_write(vcpu->kvm, KVM_MMIO_BUS, p->addr,
p->size, &p->data);
if (r)
printk(KERN_ERR"kvm: No iodevice found! addr:%lx\n", p->addr);
diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 296aba4..a7259e8 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -642,13 +642,13 @@ struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags)
kvm_register_irq_mask_notifier(kvm, 0, &pit->mask_notifier);

kvm_iodevice_init(&pit->dev, &pit_dev_ops);
- ret = __kvm_io_bus_register_dev(&kvm->pio_bus, &pit->dev);
+ ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, &pit->dev);
if (ret < 0)
goto fail;

if (flags & KVM_PIT_SPEAKER_DUMMY) {
kvm_iodevice_init(&pit->speaker_dev, &speaker_dev_ops);
- ret = __kvm_io_bus_register_dev(&kvm->pio_bus,
+ ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS,
&pit->speaker_dev);
if (ret < 0)
goto fail_unregister;
@@ -657,7 +657,7 @@ struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags)
return pit;

fail_unregister:
- __kvm_io_bus_unregister_dev(&kvm->pio_bus, &pit->dev);
+ kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &pit->dev);

fail:
if (pit->irq_source_id >= 0)
diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
index d057c0c..b7d145b 100644
--- a/arch/x86/kvm/i8259.c
+++ b/arch/x86/kvm/i8259.c
@@ -533,7 +533,9 @@ struct kvm_pic *kvm_create_pic(struct kvm *kvm)
* Initialize PIO device
*/
kvm_iodevice_init(&s->dev, &picdev_ops);
- ret = kvm_io_bus_register_dev(kvm, &kvm->pio_bus, &s->dev);
+ down_write(&kvm->slots_lock);
+ ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, &s->dev);
+ up_write(&kvm->slots_lock);
if (ret < 0) {
kfree(s);
return NULL;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 59f4da4..b9adeae 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2852,7 +2852,7 @@ static int vcpu_mmio_write(struct kvm_vcpu *vcpu, gpa_t addr, int len,
!kvm_iodevice_write(&vcpu->arch.apic->dev, addr, len, v))
return 0;

- return kvm_io_bus_write(&vcpu->kvm->mmio_bus, addr, len, v);
+ return kvm_io_bus_write(vcpu->kvm, KVM_MMIO_BUS, addr, len, v);
}

static int vcpu_mmio_read(struct kvm_vcpu *vcpu, gpa_t addr, int len, void *v)
@@ -2861,7 +2861,7 @@ static int vcpu_mmio_read(struct kvm_vcpu *vcpu, gpa_t addr, int len, void *v)
!kvm_iodevice_read(&vcpu->arch.apic->dev, addr, len, v))
return 0;

- return kvm_io_bus_read(&vcpu->kvm->mmio_bus, addr, len, v);
+ return kvm_io_bus_read(vcpu->kvm, KVM_MMIO_BUS, addr, len, v);
}

static int kvm_read_guest_virt(gva_t addr, void *val, unsigned int bytes,
@@ -3346,11 +3346,12 @@ static int kernel_pio(struct kvm_vcpu *vcpu, void *pd)
int r;

if (vcpu->arch.pio.in)
- r = kvm_io_bus_read(&vcpu->kvm->pio_bus, vcpu->arch.pio.port,
+ r = kvm_io_bus_read(vcpu->kvm, KVM_PIO_BUS, vcpu->arch.pio.port,
vcpu->arch.pio.size, pd);
else
- r = kvm_io_bus_write(&vcpu->kvm->pio_bus, vcpu->arch.pio.port,
- vcpu->arch.pio.size, pd);
+ r = kvm_io_bus_write(vcpu->kvm, KVM_PIO_BUS,
+ vcpu->arch.pio.port, vcpu->arch.pio.size,
+ pd);
return r;
}

@@ -3361,7 +3362,7 @@ static int pio_string_write(struct kvm_vcpu *vcpu)
int i, r = 0;

for (i = 0; i < io->cur_count; i++) {
- if (kvm_io_bus_write(&vcpu->kvm->pio_bus,
+ if (kvm_io_bus_write(vcpu->kvm, KVM_PIO_BUS,
io->port, io->size, pd)) {
r = -EOPNOTSUPP;
break;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 20941c0..5e9cb90 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -57,20 +57,20 @@ struct kvm_io_bus {
struct kvm_io_device *devs[NR_IOBUS_DEVS];
};

-void kvm_io_bus_init(struct kvm_io_bus *bus);
-void kvm_io_bus_destroy(struct kvm_io_bus *bus);
-int kvm_io_bus_write(struct kvm_io_bus *bus, gpa_t addr, int len,
- const void *val);
-int kvm_io_bus_read(struct kvm_io_bus *bus, gpa_t addr, int len,
+enum kvm_bus {
+ KVM_MMIO_BUS,
+ KVM_PIO_BUS,
+ KVM_NR_BUSES
+};
+
+int kvm_io_bus_write(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
+ int len, const void *val);
+int kvm_io_bus_read(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, int len,
void *val);
-int __kvm_io_bus_register_dev(struct kvm_io_bus *bus,
- struct kvm_io_device *dev);
-int kvm_io_bus_register_dev(struct kvm *kvm, struct kvm_io_bus *bus,
+int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx,
struct kvm_io_device *dev);
-void __kvm_io_bus_unregister_dev(struct kvm_io_bus *bus,
- struct kvm_io_device *dev);
-void kvm_io_bus_unregister_dev(struct kvm *kvm, struct kvm_io_bus *bus,
- struct kvm_io_device *dev);
+int kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx,
+ struct kvm_io_device *dev);

struct kvm_vcpu {
struct kvm *kvm;
@@ -171,8 +171,7 @@ struct kvm {
atomic_t online_vcpus;
struct list_head vm_list;
struct mutex lock;
- struct kvm_io_bus mmio_bus;
- struct kvm_io_bus pio_bus;
+ struct kvm_io_bus *buses[KVM_NR_BUSES];
#ifdef CONFIG_HAVE_KVM_EVENTFD
struct {
spinlock_t lock;
diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c
index d68e6c6..a736a93 100644
--- a/virt/kvm/coalesced_mmio.c
+++ b/virt/kvm/coalesced_mmio.c
@@ -110,7 +110,9 @@ int kvm_coalesced_mmio_init(struct kvm *kvm)
dev->kvm = kvm;
kvm->coalesced_mmio_dev = dev;

- ret = kvm_io_bus_register_dev(kvm, &kvm->mmio_bus, &dev->dev);
+ down_write(&kvm->slots_lock);
+ ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, &dev->dev);
+ up_write(&kvm->slots_lock);
if (ret < 0)
goto out_free_dev;

diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index a9d3fc6..315a586 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -463,7 +463,7 @@ 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;
@@ -518,7 +518,7 @@ 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;

@@ -542,7 +542,7 @@ 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;
@@ -565,7 +565,7 @@ 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;
diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
index 38a2d20..f326a6f 100644
--- a/virt/kvm/ioapic.c
+++ b/virt/kvm/ioapic.c
@@ -372,7 +372,9 @@ 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);
+ down_write(&kvm->slots_lock);
+ ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, &ioapic->dev);
+ up_write(&kvm->slots_lock);
if (ret < 0)
kfree(ioapic);

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index c680f7b..659bc12 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -85,6 +85,8 @@ 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;
@@ -367,7 +369,7 @@ static int kvm_init_mmu_notifier(struct kvm *kvm)

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;
@@ -391,6 +393,14 @@ static struct kvm *kvm_create_vm(void)
goto out_err;
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;
+ }
+ }

#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
page = alloc_page(GFP_KERNEL | __GFP_ZERO);
@@ -416,11 +426,9 @@ static struct kvm *kvm_create_vm(void)
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);
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);
atomic_set(&kvm->users_count, 1);
spin_lock(&kvm_lock);
@@ -435,6 +443,8 @@ out:
out_err:
hardware_disable_all();
out_err_nodisable:
+ for (i = 0; i < KVM_NR_BUSES; i++)
+ kfree(kvm->buses[i]);
kfree(kvm->memslots);
kfree(kvm);
return ERR_PTR(r);
@@ -480,6 +490,7 @@ void kvm_free_physmem(struct kvm *kvm)

static void kvm_destroy_vm(struct kvm *kvm)
{
+ int i;
struct mm_struct *mm = kvm->mm;

kvm_arch_sync_events(kvm);
@@ -487,8 +498,8 @@ 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);
+ 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);
@@ -1949,12 +1960,7 @@ 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;

@@ -1963,13 +1969,15 @@ 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;
@@ -1977,59 +1985,71 @@ 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 have write lock on 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 have write lock on 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 = {
--
1.6.5.3


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