[patch 3/4] KVM: introduce irq_lock, use it to protect ioapic

[Marcelo Tosatti]

Introduce irq_lock, and use to protect ioapic data structures.

Signed-off-by: Marcelo Tosatti <mtosa...@redhat.com>

Index: kvm-irqlock/include/linux/kvm_host.h
===================================================================
--- kvm-irqlock.orig/include/linux/kvm_host.h
+++ kvm-irqlock/include/linux/kvm_host.h
@@ -123,7 +123,6 @@ struct kvm_kernel_irq_routing_entry {
 };
 
 struct kvm {
-       struct mutex lock; /* protects the vcpus array and APIC accesses */
        spinlock_t mmu_lock;
        struct rw_semaphore slots_lock;
        struct mm_struct *mm; /* userspace tied to this vm */
@@ -132,6 +131,7 @@ struct kvm {
                                        KVM_PRIVATE_MEM_SLOTS];
        struct kvm_vcpu *vcpus[KVM_MAX_VCPUS];
        struct list_head vm_list;
+       struct mutex lock;
        struct kvm_io_bus mmio_bus;
        struct kvm_io_bus pio_bus;
 #ifdef CONFIG_HAVE_KVM_EVENTFD
@@ -145,6 +145,7 @@ struct kvm {
        struct kvm_coalesced_mmio_ring *coalesced_mmio_ring;
 #endif
 
+       struct mutex irq_lock;
 #ifdef CONFIG_HAVE_KVM_IRQCHIP
        struct list_head irq_routing; /* of kvm_kernel_irq_routing_entry */
        struct hlist_head mask_notifier_list;
Index: kvm-irqlock/virt/kvm/ioapic.c
===================================================================
--- kvm-irqlock.orig/virt/kvm/ioapic.c
+++ kvm-irqlock/virt/kvm/ioapic.c
@@ -238,6 +238,7 @@ static void ioapic_mmio_read(struct kvm_
        ioapic_debug("addr %lx\n", (unsigned long)addr);
        ASSERT(!(addr & 0xf));  /* check alignment */
 
+       mutex_lock(&ioapic->kvm->irq_lock);
        addr &= 0xff;
        switch (addr) {
        case IOAPIC_REG_SELECT:
@@ -264,6 +265,7 @@ static void ioapic_mmio_read(struct kvm_
        default:
                printk(KERN_WARNING "ioapic: wrong length %d\n", len);
        }
+       mutex_unlock(&ioapic->kvm->irq_lock);
 }
 
 static void ioapic_mmio_write(struct kvm_io_device *this, gpa_t addr, int len,
@@ -275,6 +277,8 @@ static void ioapic_mmio_write(struct kvm
        ioapic_debug("ioapic_mmio_write addr=%p len=%d val=%p\n",
                     (void*)addr, len, val);
        ASSERT(!(addr & 0xf));  /* check alignment */
+
+       mutex_lock(&ioapic->kvm->irq_lock);
        if (len == 4 || len == 8)
                data = *(u32 *) val;
        else {
@@ -300,6 +304,7 @@ static void ioapic_mmio_write(struct kvm
        default:
                break;
        }
+       mutex_unlock(&ioapic->kvm->irq_lock);
 }
 
 void kvm_ioapic_reset(struct kvm_ioapic *ioapic)
Index: kvm-irqlock/virt/kvm/kvm_main.c
===================================================================
--- kvm-irqlock.orig/virt/kvm/kvm_main.c
+++ kvm-irqlock/virt/kvm/kvm_main.c
@@ -985,6 +985,7 @@ static struct kvm *kvm_create_vm(void)
        kvm_io_bus_init(&kvm->pio_bus);
        kvm_irqfd_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);

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