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Subject[PATCH 15/42] KVM: Move IO APIC to its own lock
Date
From: Gleb Natapov <gleb@redhat.com>

The allows removal of irq_lock from the injection path.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
---
arch/ia64/kvm/kvm-ia64.c | 7 +---
arch/x86/kvm/i8259.c | 22 +++++++++---
arch/x86/kvm/lapic.c | 5 +--
arch/x86/kvm/x86.c | 10 +----
virt/kvm/ioapic.c | 80 +++++++++++++++++++++++++++++++++++-----------
virt/kvm/ioapic.h | 4 ++
virt/kvm/irq_comm.c | 23 ++++++++-----
7 files changed, 100 insertions(+), 51 deletions(-)
diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index 0ad09f0..4a98314 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -851,8 +851,7 @@ static int kvm_vm_ioctl_get_irqchip(struct kvm *kvm,
r = 0;
switch (chip->chip_id) {
case KVM_IRQCHIP_IOAPIC:
- memcpy(&chip->chip.ioapic, ioapic_irqchip(kvm),
- sizeof(struct kvm_ioapic_state));
+ r = kvm_get_ioapic(kvm, &chip->chip.ioapic);
break;
default:
r = -EINVAL;
@@ -868,9 +867,7 @@ static int kvm_vm_ioctl_set_irqchip(struct kvm *kvm, struct kvm_irqchip *chip)
r = 0;
switch (chip->chip_id) {
case KVM_IRQCHIP_IOAPIC:
- memcpy(ioapic_irqchip(kvm),
- &chip->chip.ioapic,
- sizeof(struct kvm_ioapic_state));
+ r = kvm_set_ioapic(kvm, &chip->chip.ioapic);
break;
default:
r = -EINVAL;
diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
index ccc941a..d057c0c 100644
--- a/arch/x86/kvm/i8259.c
+++ b/arch/x86/kvm/i8259.c
@@ -38,7 +38,15 @@ static void pic_clear_isr(struct kvm_kpic_state *s, int irq)
s->isr_ack |= (1 << irq);
if (s != &s->pics_state->pics[0])
irq += 8;
+ /*
+ * We are dropping lock while calling ack notifiers since ack
+ * notifier callbacks for assigned devices call into PIC recursively.
+ * Other interrupt may be delivered to PIC while lock is dropped but
+ * it should be safe since PIC state is already updated at this stage.
+ */
+ spin_unlock(&s->pics_state->lock);
kvm_notify_acked_irq(s->pics_state->kvm, SELECT_PIC(irq), irq);
+ spin_lock(&s->pics_state->lock);
}

void kvm_pic_clear_isr_ack(struct kvm *kvm)
@@ -176,16 +184,18 @@ int kvm_pic_set_irq(void *opaque, int irq, int level)
static inline void pic_intack(struct kvm_kpic_state *s, int irq)
{
s->isr |= 1 << irq;
- if (s->auto_eoi) {
- if (s->rotate_on_auto_eoi)
- s->priority_add = (irq + 1) & 7;
- pic_clear_isr(s, irq);
- }
/*
* We don't clear a level sensitive interrupt here
*/
if (!(s->elcr & (1 << irq)))
s->irr &= ~(1 << irq);
+
+ if (s->auto_eoi) {
+ if (s->rotate_on_auto_eoi)
+ s->priority_add = (irq + 1) & 7;
+ pic_clear_isr(s, irq);
+ }
+
}

int kvm_pic_read_irq(struct kvm *kvm)
@@ -294,9 +304,9 @@ static void pic_ioport_write(void *opaque, u32 addr, u32 val)
priority = get_priority(s, s->isr);
if (priority != 8) {
irq = (priority + s->priority_add) & 7;
- pic_clear_isr(s, irq);
if (cmd == 5)
s->priority_add = (irq + 1) & 7;
+ pic_clear_isr(s, irq);
pic_update_irq(s->pics_state);
}
break;
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 23c2176..df8bcb0 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -471,11 +471,8 @@ static void apic_set_eoi(struct kvm_lapic *apic)
trigger_mode = IOAPIC_LEVEL_TRIG;
else
trigger_mode = IOAPIC_EDGE_TRIG;
- if (!(apic_get_reg(apic, APIC_SPIV) & APIC_SPIV_DIRECTED_EOI)) {
- mutex_lock(&apic->vcpu->kvm->irq_lock);
+ if (!(apic_get_reg(apic, APIC_SPIV) & APIC_SPIV_DIRECTED_EOI))
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)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1687d12..fdf989f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2038,9 +2038,7 @@ static int kvm_vm_ioctl_get_irqchip(struct kvm *kvm, struct kvm_irqchip *chip)
sizeof(struct kvm_pic_state));
break;
case KVM_IRQCHIP_IOAPIC:
- memcpy(&chip->chip.ioapic,
- ioapic_irqchip(kvm),
- sizeof(struct kvm_ioapic_state));
+ r = kvm_get_ioapic(kvm, &chip->chip.ioapic);
break;
default:
r = -EINVAL;
@@ -2070,11 +2068,7 @@ static int kvm_vm_ioctl_set_irqchip(struct kvm *kvm, struct kvm_irqchip *chip)
spin_unlock(&pic_irqchip(kvm)->lock);
break;
case KVM_IRQCHIP_IOAPIC:
- mutex_lock(&kvm->irq_lock);
- memcpy(ioapic_irqchip(kvm),
- &chip->chip.ioapic,
- sizeof(struct kvm_ioapic_state));
- mutex_unlock(&kvm->irq_lock);
+ r = kvm_set_ioapic(kvm, &chip->chip.ioapic);
break;
default:
r = -EINVAL;
diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
index 9fe140b..38a2d20 100644
--- a/virt/kvm/ioapic.c
+++ b/virt/kvm/ioapic.c
@@ -182,6 +182,7 @@ int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int level)
union kvm_ioapic_redirect_entry entry;
int ret = 1;

+ mutex_lock(&ioapic->lock);
if (irq >= 0 && irq < IOAPIC_NUM_PINS) {
entry = ioapic->redirtbl[irq];
level ^= entry.fields.polarity;
@@ -198,34 +199,51 @@ int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int level)
}
trace_kvm_ioapic_set_irq(entry.bits, irq, ret == 0);
}
+ mutex_unlock(&ioapic->lock);
+
return ret;
}

-static void __kvm_ioapic_update_eoi(struct kvm_ioapic *ioapic, int pin,
- int trigger_mode)
+static void __kvm_ioapic_update_eoi(struct kvm_ioapic *ioapic, int vector,
+ int trigger_mode)
{
- union kvm_ioapic_redirect_entry *ent;
+ int i;
+
+ for (i = 0; i < IOAPIC_NUM_PINS; i++) {
+ union kvm_ioapic_redirect_entry *ent = &ioapic->redirtbl[i];

- ent = &ioapic->redirtbl[pin];
+ if (ent->fields.vector != vector)
+ continue;

- kvm_notify_acked_irq(ioapic->kvm, KVM_IRQCHIP_IOAPIC, pin);
+ /*
+ * We are dropping lock while calling ack notifiers because ack
+ * notifier callbacks for assigned devices call into IOAPIC
+ * recursively. Since remote_irr is cleared only after call
+ * to notifiers if the same vector will be delivered while lock
+ * is dropped it will be put into irr and will be delivered
+ * after ack notifier returns.
+ */
+ mutex_unlock(&ioapic->lock);
+ kvm_notify_acked_irq(ioapic->kvm, KVM_IRQCHIP_IOAPIC, i);
+ mutex_lock(&ioapic->lock);
+
+ if (trigger_mode != IOAPIC_LEVEL_TRIG)
+ continue;

- if (trigger_mode == IOAPIC_LEVEL_TRIG) {
ASSERT(ent->fields.trig_mode == IOAPIC_LEVEL_TRIG);
ent->fields.remote_irr = 0;
- if (!ent->fields.mask && (ioapic->irr & (1 << pin)))
- ioapic_service(ioapic, pin);
+ if (!ent->fields.mask && (ioapic->irr & (1 << i)))
+ ioapic_service(ioapic, i);
}
}

void kvm_ioapic_update_eoi(struct kvm *kvm, int vector, int trigger_mode)
{
struct kvm_ioapic *ioapic = kvm->arch.vioapic;
- int i;

- for (i = 0; i < IOAPIC_NUM_PINS; i++)
- if (ioapic->redirtbl[i].fields.vector == vector)
- __kvm_ioapic_update_eoi(ioapic, i, trigger_mode);
+ mutex_lock(&ioapic->lock);
+ __kvm_ioapic_update_eoi(ioapic, vector, trigger_mode);
+ mutex_unlock(&ioapic->lock);
}

static inline struct kvm_ioapic *to_ioapic(struct kvm_io_device *dev)
@@ -250,8 +268,8 @@ static int ioapic_mmio_read(struct kvm_io_device *this, gpa_t addr, int len,
ioapic_debug("addr %lx\n", (unsigned long)addr);
ASSERT(!(addr & 0xf)); /* check alignment */

- mutex_lock(&ioapic->kvm->irq_lock);
addr &= 0xff;
+ mutex_lock(&ioapic->lock);
switch (addr) {
case IOAPIC_REG_SELECT:
result = ioapic->ioregsel;
@@ -265,6 +283,8 @@ static int ioapic_mmio_read(struct kvm_io_device *this, gpa_t addr, int len,
result = 0;
break;
}
+ mutex_unlock(&ioapic->lock);
+
switch (len) {
case 8:
*(u64 *) val = result;
@@ -277,7 +297,6 @@ static int ioapic_mmio_read(struct kvm_io_device *this, gpa_t addr, int len,
default:
printk(KERN_WARNING "ioapic: wrong length %d\n", len);
}
- mutex_unlock(&ioapic->kvm->irq_lock);
return 0;
}

@@ -293,15 +312,15 @@ static int ioapic_mmio_write(struct kvm_io_device *this, gpa_t addr, int len,
(void*)addr, len, val);
ASSERT(!(addr & 0xf)); /* check alignment */

- mutex_lock(&ioapic->kvm->irq_lock);
if (len == 4 || len == 8)
data = *(u32 *) val;
else {
printk(KERN_WARNING "ioapic: Unsupported size %d\n", len);
- goto unlock;
+ return 0;
}

addr &= 0xff;
+ mutex_lock(&ioapic->lock);
switch (addr) {
case IOAPIC_REG_SELECT:
ioapic->ioregsel = data;
@@ -312,15 +331,14 @@ static int ioapic_mmio_write(struct kvm_io_device *this, gpa_t addr, int len,
break;
#ifdef CONFIG_IA64
case IOAPIC_REG_EOI:
- kvm_ioapic_update_eoi(ioapic->kvm, data, IOAPIC_LEVEL_TRIG);
+ __kvm_ioapic_update_eoi(ioapic, data, IOAPIC_LEVEL_TRIG);
break;
#endif

default:
break;
}
-unlock:
- mutex_unlock(&ioapic->kvm->irq_lock);
+ mutex_unlock(&ioapic->lock);
return 0;
}

@@ -349,6 +367,7 @@ int kvm_ioapic_init(struct kvm *kvm)
ioapic = kzalloc(sizeof(struct kvm_ioapic), GFP_KERNEL);
if (!ioapic)
return -ENOMEM;
+ mutex_init(&ioapic->lock);
kvm->arch.vioapic = ioapic;
kvm_ioapic_reset(ioapic);
kvm_iodevice_init(&ioapic->dev, &ioapic_mmio_ops);
@@ -360,3 +379,26 @@ int kvm_ioapic_init(struct kvm *kvm)
return ret;
}

+int kvm_get_ioapic(struct kvm *kvm, struct kvm_ioapic_state *state)
+{
+ struct kvm_ioapic *ioapic = ioapic_irqchip(kvm);
+ if (!ioapic)
+ return -EINVAL;
+
+ mutex_lock(&ioapic->lock);
+ memcpy(state, ioapic, sizeof(struct kvm_ioapic_state));
+ mutex_unlock(&ioapic->lock);
+ return 0;
+}
+
+int kvm_set_ioapic(struct kvm *kvm, struct kvm_ioapic_state *state)
+{
+ struct kvm_ioapic *ioapic = ioapic_irqchip(kvm);
+ if (!ioapic)
+ return -EINVAL;
+
+ mutex_lock(&ioapic->lock);
+ memcpy(ioapic, state, sizeof(struct kvm_ioapic_state));
+ mutex_unlock(&ioapic->lock);
+ return 0;
+}
diff --git a/virt/kvm/ioapic.h b/virt/kvm/ioapic.h
index 6e461ad..419c43b 100644
--- a/virt/kvm/ioapic.h
+++ b/virt/kvm/ioapic.h
@@ -45,6 +45,7 @@ struct kvm_ioapic {
struct kvm_io_device dev;
struct kvm *kvm;
void (*ack_notifier)(void *opaque, int irq);
+ struct mutex lock;
};

#ifdef DEBUG
@@ -74,4 +75,7 @@ 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,
struct kvm_lapic_irq *irq);
+int kvm_get_ioapic(struct kvm *kvm, struct kvm_ioapic_state *state);
+int kvm_set_ioapic(struct kvm *kvm, struct kvm_ioapic_state *state);
+
#endif
diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index 6c94614..fadf440 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -146,8 +146,8 @@ static int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
*/
int kvm_set_irq(struct kvm *kvm, int irq_source_id, u32 irq, int level)
{
- struct kvm_kernel_irq_routing_entry *e;
- int ret = -1;
+ struct kvm_kernel_irq_routing_entry *e, irq_set[KVM_NR_IRQCHIPS];
+ int ret = -1, i = 0;
struct kvm_irq_routing_table *irq_rt;
struct hlist_node *n;

@@ -162,14 +162,19 @@ int kvm_set_irq(struct kvm *kvm, int irq_source_id, u32 irq, int level)
rcu_read_lock();
irq_rt = rcu_dereference(kvm->irq_routing);
if (irq < irq_rt->nr_rt_entries)
- hlist_for_each_entry(e, n, &irq_rt->map[irq], link) {
- int r = e->set(e, kvm, irq_source_id, level);
- if (r < 0)
- continue;
-
- ret = r + ((ret < 0) ? 0 : ret);
- }
+ hlist_for_each_entry(e, n, &irq_rt->map[irq], link)
+ irq_set[i++] = *e;
rcu_read_unlock();
+
+ while(i--) {
+ int r;
+ r = irq_set[i].set(&irq_set[i], kvm, irq_source_id, level);
+ if (r < 0)
+ continue;
+
+ ret = r + ((ret < 0) ? 0 : ret);
+ }
+
return ret;
}

--
1.6.5.2


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