[PATCH 28/35] KVM: x86: disallow multiple KVM_CREATE_IRQCHIP

[Avi Kivity]

From: Marcelo Tosatti <mtosa...@redhat.com>

Otherwise kvm will leak memory on multiple KVM_CREATE_IRQCHIP.
Also serialize multiple accesses with kvm->lock.

Signed-off-by: Marcelo Tosatti <mtosa...@redhat.com>
Signed-off-by: Avi Kivity <a...@redhat.com>
---
 arch/x86/kvm/irq.h |    6 +++++-
 arch/x86/kvm/x86.c |   30 ++++++++++++++++++++++--------
 2 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/irq.h b/arch/x86/kvm/irq.h
index c025a23..be399e2 100644
--- a/arch/x86/kvm/irq.h
+++ b/arch/x86/kvm/irq.h
@@ -86,7 +86,11 @@ static inline struct kvm_pic *pic_irqchip(struct kvm *kvm)
 
 static inline int irqchip_in_kernel(struct kvm *kvm)
 {
-       return pic_irqchip(kvm) != NULL;
+       int ret;
+
+       ret = (pic_irqchip(kvm) != NULL);
+       smp_rmb();
+       return ret;
 }
 
 void kvm_pic_reset(struct kvm_kpic_state *s);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 719f31e..97f6f95 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2362,25 +2362,39 @@ long kvm_arch_vm_ioctl(struct file *filp,
                if (r)
                        goto out;
                break;
-       case KVM_CREATE_IRQCHIP:
+       case KVM_CREATE_IRQCHIP: {
+               struct kvm_pic *vpic;
+
+               mutex_lock(&kvm->lock);
+               r = -EEXIST;
+               if (kvm->arch.vpic)
+                       goto create_irqchip_unlock;
                r = -ENOMEM;
-               kvm->arch.vpic = kvm_create_pic(kvm);
-               if (kvm->arch.vpic) {
+               vpic = kvm_create_pic(kvm);
+               if (vpic) {
                        r = kvm_ioapic_init(kvm);
                        if (r) {
-                               kfree(kvm->arch.vpic);
-                               kvm->arch.vpic = NULL;
-                               goto out;
+                               kfree(vpic);
+                               goto create_irqchip_unlock;
                        }
                } else
-                       goto out;
+                       goto create_irqchip_unlock;
+               smp_wmb();
+               kvm->arch.vpic = vpic;
+               smp_wmb();
                r = kvm_setup_default_irq_routing(kvm);
                if (r) {
+                       mutex_lock(&kvm->irq_lock);
                        kfree(kvm->arch.vpic);
                        kfree(kvm->arch.vioapic);
-                       goto out;
+                       kvm->arch.vpic = NULL;
+                       kvm->arch.vioapic = NULL;
+                       mutex_unlock(&kvm->irq_lock);
                }
+       create_irqchip_unlock:
+               mutex_unlock(&kvm->lock);
                break;
+       }
        case KVM_CREATE_PIT:
                u.pit_config.flags = KVM_PIT_SPEAKER_DUMMY;
                goto create_pit;
-- 
1.6.5.2

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