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Subject[PATCH 38/48] KVM: switch irq injection/acking data structures to irq_lock
Date
From: Marcelo Tosatti <mtosatti@redhat.com>

Protect irq injection/acking data structures with a separate irq_lock
mutex. This fixes the following deadlock:

CPU A CPU B
kvm_vm_ioctl_deassign_dev_irq()
mutex_lock(&kvm->lock); worker_thread()
-> kvm_deassign_irq() -> kvm_assigned_dev_interrupt_work_handler()
-> deassign_host_irq() mutex_lock(&kvm->lock);
-> cancel_work_sync() [blocked]

[gleb: fix ia64 path]

Reported-by: Alex Williamson <alex.williamson@hp.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
---
arch/ia64/kvm/kvm-ia64.c | 4 ++--
arch/x86/kvm/i8254.c | 4 ++--
arch/x86/kvm/lapic.c | 4 ++++
arch/x86/kvm/x86.c | 19 +++++++++----------
include/linux/kvm_host.h | 3 ++-
virt/kvm/eventfd.c | 4 ++--
virt/kvm/irq_comm.c | 34 ++++++++++++++++++++++++++++------
virt/kvm/kvm_main.c | 16 +++++++++-------
8 files changed, 58 insertions(+), 30 deletions(-)
diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index 3199221..8dde369 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -1000,10 +1000,10 @@ long kvm_arch_vm_ioctl(struct file *filp,
goto out;
if (irqchip_in_kernel(kvm)) {
__s32 status;
- mutex_lock(&kvm->lock);
+ mutex_lock(&kvm->irq_lock);
status = kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID,
irq_event.irq, irq_event.level);
- mutex_unlock(&kvm->lock);
+ mutex_unlock(&kvm->irq_lock);
if (ioctl == KVM_IRQ_LINE_STATUS) {
irq_event.status = status;
if (copy_to_user(argp, &irq_event,
diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 977af7a..3837db6 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -654,10 +654,10 @@ static void __inject_pit_timer_intr(struct kvm *kvm)
struct kvm_vcpu *vcpu;
int i;

- mutex_lock(&kvm->lock);
+ mutex_lock(&kvm->irq_lock);
kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 1);
kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 0);
- mutex_unlock(&kvm->lock);
+ mutex_unlock(&kvm->irq_lock);

/*
* Provides NMI watchdog support via Virtual Wire mode.
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index a23f42e..44f20cd 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -424,7 +424,9 @@ static void apic_set_eoi(struct kvm_lapic *apic)
trigger_mode = IOAPIC_LEVEL_TRIG;
else
trigger_mode = IOAPIC_EDGE_TRIG;
+ mutex_lock(&apic->vcpu->kvm->irq_lock);
kvm_ioapic_update_eoi(apic->vcpu->kvm, vector, trigger_mode);
+ mutex_unlock(&apic->vcpu->kvm->irq_lock);
}

static void apic_send_ipi(struct kvm_lapic *apic)
@@ -448,7 +450,9 @@ static void apic_send_ipi(struct kvm_lapic *apic)
irq.trig_mode, irq.level, irq.dest_mode, irq.delivery_mode,
irq.vector);

+ mutex_lock(&apic->vcpu->kvm->irq_lock);
kvm_irq_delivery_to_apic(apic->vcpu->kvm, apic, &irq);
+ mutex_unlock(&apic->vcpu->kvm->irq_lock);
}

static u32 apic_get_tmcct(struct kvm_lapic *apic)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2ad8c97..05cbe83 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2136,10 +2136,10 @@ long kvm_arch_vm_ioctl(struct file *filp,
goto out;
if (irqchip_in_kernel(kvm)) {
__s32 status;
- mutex_lock(&kvm->lock);
+ mutex_lock(&kvm->irq_lock);
status = kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID,
irq_event.irq, irq_event.level);
- mutex_unlock(&kvm->lock);
+ mutex_unlock(&kvm->irq_lock);
if (ioctl == KVM_IRQ_LINE_STATUS) {
irq_event.status = status;
if (copy_to_user(argp, &irq_event,
@@ -2385,12 +2385,11 @@ mmio:
*/
mutex_lock(&vcpu->kvm->lock);
mmio_dev = vcpu_find_mmio_dev(vcpu, gpa, bytes, 0);
+ mutex_unlock(&vcpu->kvm->lock);
if (mmio_dev) {
kvm_iodevice_read(mmio_dev, gpa, bytes, val);
- mutex_unlock(&vcpu->kvm->lock);
return X86EMUL_CONTINUE;
}
- mutex_unlock(&vcpu->kvm->lock);

vcpu->mmio_needed = 1;
vcpu->mmio_phys_addr = gpa;
@@ -2440,12 +2439,11 @@ mmio:
*/
mutex_lock(&vcpu->kvm->lock);
mmio_dev = vcpu_find_mmio_dev(vcpu, gpa, bytes, 1);
+ mutex_unlock(&vcpu->kvm->lock);
if (mmio_dev) {
kvm_iodevice_write(mmio_dev, gpa, bytes, val);
- mutex_unlock(&vcpu->kvm->lock);
return X86EMUL_CONTINUE;
}
- mutex_unlock(&vcpu->kvm->lock);

vcpu->mmio_needed = 1;
vcpu->mmio_phys_addr = gpa;
@@ -2768,7 +2766,6 @@ static void kernel_pio(struct kvm_io_device *pio_dev,
{
/* TODO: String I/O for in kernel device */

- mutex_lock(&vcpu->kvm->lock);
if (vcpu->arch.pio.in)
kvm_iodevice_read(pio_dev, vcpu->arch.pio.port,
vcpu->arch.pio.size,
@@ -2777,7 +2774,6 @@ static void kernel_pio(struct kvm_io_device *pio_dev,
kvm_iodevice_write(pio_dev, vcpu->arch.pio.port,
vcpu->arch.pio.size,
pd);
- mutex_unlock(&vcpu->kvm->lock);
}

static void pio_string_write(struct kvm_io_device *pio_dev,
@@ -2787,14 +2783,12 @@ static void pio_string_write(struct kvm_io_device *pio_dev,
void *pd = vcpu->arch.pio_data;
int i;

- mutex_lock(&vcpu->kvm->lock);
for (i = 0; i < io->cur_count; i++) {
kvm_iodevice_write(pio_dev, io->port,
io->size,
pd);
pd += io->size;
}
- mutex_unlock(&vcpu->kvm->lock);
}

static struct kvm_io_device *vcpu_find_pio_dev(struct kvm_vcpu *vcpu,
@@ -2831,7 +2825,9 @@ int kvm_emulate_pio(struct kvm_vcpu *vcpu, struct kvm_run *run, int in,
val = kvm_register_read(vcpu, VCPU_REGS_RAX);
memcpy(vcpu->arch.pio_data, &val, 4);

+ mutex_lock(&vcpu->kvm->lock);
pio_dev = vcpu_find_pio_dev(vcpu, port, size, !in);
+ mutex_unlock(&vcpu->kvm->lock);
if (pio_dev) {
kernel_pio(pio_dev, vcpu, vcpu->arch.pio_data);
complete_pio(vcpu);
@@ -2895,9 +2891,12 @@ int kvm_emulate_pio_string(struct kvm_vcpu *vcpu, struct kvm_run *run, int in,

vcpu->arch.pio.guest_gva = address;

+ mutex_lock(&vcpu->kvm->lock);
pio_dev = vcpu_find_pio_dev(vcpu, port,
vcpu->arch.pio.cur_count,
!vcpu->arch.pio.in);
+ mutex_unlock(&vcpu->kvm->lock);
+
if (!vcpu->arch.pio.in) {
/* string PIO write */
ret = pio_copy_data(vcpu);
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 0c71688..a29ea03 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -371,7 +371,8 @@ int kvm_set_irq(struct kvm *kvm, int irq_source_id, int irq, int level);
void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin);
void kvm_register_irq_ack_notifier(struct kvm *kvm,
struct kvm_irq_ack_notifier *kian);
-void kvm_unregister_irq_ack_notifier(struct kvm_irq_ack_notifier *kian);
+void kvm_unregister_irq_ack_notifier(struct kvm *kvm,
+ struct kvm_irq_ack_notifier *kian);
int kvm_request_irq_source_id(struct kvm *kvm);
void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id);

diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index 3140123..4092b8d 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -57,10 +57,10 @@ irqfd_inject(struct work_struct *work)
struct _irqfd *irqfd = container_of(work, struct _irqfd, inject);
struct kvm *kvm = irqfd->kvm;

- mutex_lock(&kvm->lock);
+ mutex_lock(&kvm->irq_lock);
kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1);
kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0);
- mutex_unlock(&kvm->lock);
+ mutex_unlock(&kvm->irq_lock);
}

/*
diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index ddc17f0..08a9a49 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -62,6 +62,8 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
int i, r = -1;
struct kvm_vcpu *vcpu, *lowest = NULL;

+ WARN_ON(!mutex_is_locked(&kvm->irq_lock));
+
if (irq->dest_mode == 0 && irq->dest_id == 0xff &&
kvm_is_dm_lowest_prio(irq))
printk(KERN_INFO "kvm: apic: phys broadcast and lowest prio\n");
@@ -113,7 +115,7 @@ static int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
return kvm_irq_delivery_to_apic(kvm, NULL, &irq);
}

-/* This should be called with the kvm->lock mutex held
+/* This should be called with the kvm->irq_lock mutex held
* Return value:
* < 0 Interrupt was ignored (masked or not delivered for other reasons)
* = 0 Interrupt was coalesced (previous irq is still pending)
@@ -125,6 +127,8 @@ int kvm_set_irq(struct kvm *kvm, int irq_source_id, int irq, int level)
unsigned long *irq_state, sig_level;
int ret = -1;

+ WARN_ON(!mutex_is_locked(&kvm->irq_lock));
+
if (irq < KVM_IOAPIC_NUM_PINS) {
irq_state = (unsigned long *)&kvm->arch.irq_states[irq];

@@ -175,19 +179,26 @@ void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
void kvm_register_irq_ack_notifier(struct kvm *kvm,
struct kvm_irq_ack_notifier *kian)
{
+ mutex_lock(&kvm->irq_lock);
hlist_add_head(&kian->link, &kvm->arch.irq_ack_notifier_list);
+ mutex_unlock(&kvm->irq_lock);
}

-void kvm_unregister_irq_ack_notifier(struct kvm_irq_ack_notifier *kian)
+void kvm_unregister_irq_ack_notifier(struct kvm *kvm,
+ struct kvm_irq_ack_notifier *kian)
{
+ mutex_lock(&kvm->irq_lock);
hlist_del_init(&kian->link);
+ mutex_unlock(&kvm->irq_lock);
}

-/* The caller must hold kvm->lock mutex */
int kvm_request_irq_source_id(struct kvm *kvm)
{
unsigned long *bitmap = &kvm->arch.irq_sources_bitmap;
- int irq_source_id = find_first_zero_bit(bitmap,
+ int irq_source_id;
+
+ mutex_lock(&kvm->irq_lock);
+ irq_source_id = find_first_zero_bit(bitmap,
sizeof(kvm->arch.irq_sources_bitmap));

if (irq_source_id >= sizeof(kvm->arch.irq_sources_bitmap)) {
@@ -197,6 +208,7 @@ int kvm_request_irq_source_id(struct kvm *kvm)

ASSERT(irq_source_id != KVM_USERSPACE_IRQ_SOURCE_ID);
set_bit(irq_source_id, bitmap);
+ mutex_unlock(&kvm->irq_lock);

return irq_source_id;
}
@@ -207,6 +219,7 @@ void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id)

ASSERT(irq_source_id != KVM_USERSPACE_IRQ_SOURCE_ID);

+ mutex_lock(&kvm->irq_lock);
if (irq_source_id < 0 ||
irq_source_id >= sizeof(kvm->arch.irq_sources_bitmap)) {
printk(KERN_ERR "kvm: IRQ source ID out of range!\n");
@@ -215,19 +228,24 @@ void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id)
for (i = 0; i < KVM_IOAPIC_NUM_PINS; i++)
clear_bit(irq_source_id, &kvm->arch.irq_states[i]);
clear_bit(irq_source_id, &kvm->arch.irq_sources_bitmap);
+ mutex_unlock(&kvm->irq_lock);
}

void kvm_register_irq_mask_notifier(struct kvm *kvm, int irq,
struct kvm_irq_mask_notifier *kimn)
{
+ mutex_lock(&kvm->irq_lock);
kimn->irq = irq;
hlist_add_head(&kimn->link, &kvm->mask_notifier_list);
+ mutex_unlock(&kvm->irq_lock);
}

void kvm_unregister_irq_mask_notifier(struct kvm *kvm, int irq,
struct kvm_irq_mask_notifier *kimn)
{
+ mutex_lock(&kvm->irq_lock);
hlist_del(&kimn->link);
+ mutex_unlock(&kvm->irq_lock);
}

void kvm_fire_mask_notifiers(struct kvm *kvm, int irq, bool mask)
@@ -235,6 +253,8 @@ void kvm_fire_mask_notifiers(struct kvm *kvm, int irq, bool mask)
struct kvm_irq_mask_notifier *kimn;
struct hlist_node *n;

+ WARN_ON(!mutex_is_locked(&kvm->irq_lock));
+
hlist_for_each_entry(kimn, n, &kvm->mask_notifier_list, link)
if (kimn->irq == irq)
kimn->func(kimn, mask);
@@ -250,7 +270,9 @@ static void __kvm_free_irq_routing(struct list_head *irq_routing)

void kvm_free_irq_routing(struct kvm *kvm)
{
+ mutex_lock(&kvm->irq_lock);
__kvm_free_irq_routing(&kvm->irq_routing);
+ mutex_unlock(&kvm->irq_lock);
}

static int setup_routing_entry(struct kvm_kernel_irq_routing_entry *e,
@@ -325,13 +347,13 @@ int kvm_set_irq_routing(struct kvm *kvm,
e = NULL;
}

- mutex_lock(&kvm->lock);
+ mutex_lock(&kvm->irq_lock);
list_splice(&kvm->irq_routing, &tmp);
INIT_LIST_HEAD(&kvm->irq_routing);
list_splice(&irq_list, &kvm->irq_routing);
INIT_LIST_HEAD(&irq_list);
list_splice(&tmp, &irq_list);
- mutex_unlock(&kvm->lock);
+ mutex_unlock(&kvm->irq_lock);

r = 0;

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d47e660..0d481b2 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -62,6 +62,12 @@
MODULE_AUTHOR("Qumranet");
MODULE_LICENSE("GPL");

+/*
+ * Ordering of locks:
+ *
+ * kvm->lock --> kvm->irq_lock
+ */
+
DEFINE_SPINLOCK(kvm_lock);
LIST_HEAD(vm_list);

@@ -126,11 +132,7 @@ static void kvm_assigned_dev_interrupt_work_handler(struct work_struct *work)
interrupt_work);
kvm = assigned_dev->kvm;

- /* This is taken to safely inject irq inside the guest. When
- * the interrupt injection (or the ioapic code) uses a
- * finer-grained lock, update this
- */
- mutex_lock(&kvm->lock);
+ mutex_lock(&kvm->irq_lock);
spin_lock_irq(&assigned_dev->assigned_dev_lock);
if (assigned_dev->irq_requested_type & KVM_DEV_IRQ_HOST_MSIX) {
struct kvm_guest_msix_entry *guest_entries =
@@ -149,7 +151,7 @@ static void kvm_assigned_dev_interrupt_work_handler(struct work_struct *work)
assigned_dev->guest_irq, 1);

spin_unlock_irq(&assigned_dev->assigned_dev_lock);
- mutex_unlock(&assigned_dev->kvm->lock);
+ mutex_unlock(&assigned_dev->kvm->irq_lock);
}

static irqreturn_t kvm_assigned_dev_intr(int irq, void *dev_id)
@@ -207,7 +209,7 @@ static void kvm_assigned_dev_ack_irq(struct kvm_irq_ack_notifier *kian)
static void deassign_guest_irq(struct kvm *kvm,
struct kvm_assigned_dev_kernel *assigned_dev)
{
- kvm_unregister_irq_ack_notifier(&assigned_dev->ack_notifier);
+ kvm_unregister_irq_ack_notifier(kvm, &assigned_dev->ack_notifier);
assigned_dev->ack_notifier.gsi = -1;

if (assigned_dev->irq_source_id != -1)
--
1.6.3.3


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