From 71ba994c94a81c37185ef2fb5190844286ba9aca Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Wed, 29 Jul 2015 12:31:15 +0200 Subject: KVM: x86: clean/fix memory barriers in irqchip_in_kernel The memory barriers are trying to protect against concurrent RCU-based interrupt injection, but the IRQ routing table is not valid at the time kvm->arch.vpic is written. Fix this by writing kvm->arch.vpic last. kvm_destroy_pic then need not set kvm->arch.vpic to NULL; modify it to take a struct kvm_pic* and reuse it if the IOAPIC creation fails. Signed-off-by: Paolo Bonzini --- arch/x86/kvm/irq.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'arch/x86/kvm/irq.h') diff --git a/arch/x86/kvm/irq.h b/arch/x86/kvm/irq.h index ad68c73008c5..3d782a2c336a 100644 --- a/arch/x86/kvm/irq.h +++ b/arch/x86/kvm/irq.h @@ -74,7 +74,7 @@ struct kvm_pic { }; struct kvm_pic *kvm_create_pic(struct kvm *kvm); -void kvm_destroy_pic(struct kvm *kvm); +void kvm_destroy_pic(struct kvm_pic *vpic); int kvm_pic_read_irq(struct kvm *kvm); void kvm_pic_update_irq(struct kvm_pic *s); @@ -85,11 +85,11 @@ static inline struct kvm_pic *pic_irqchip(struct kvm *kvm) static inline int irqchip_in_kernel(struct kvm *kvm) { - int ret; + struct kvm_pic *vpic = pic_irqchip(kvm); - ret = (pic_irqchip(kvm) != NULL); + /* Read vpic before kvm->irq_routing. */ smp_rmb(); - return ret; + return vpic != NULL; } void kvm_pic_reset(struct kvm_kpic_state *s); -- cgit