KVM: Move IO APIC to its own lock

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>

7 files changed, 100 insertions, 51 deletions

diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index 0ad09f05efa9..4a983147f6eb 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 ccc941af4eaf..d057c0cbd245 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 23c217692ea9..df8bcb0f66d8 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 1687d12b122a..fdf989f17a61 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 9fe140bb38ec..38a2d20b89de 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 6e461ade6365..419c43b667ab 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 6c946141dbcc..fadf4408a820 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;
 }