From 42720138b06301cc8a7ee8a495a6d021c4b6a9bc Mon Sep 17 00:00:00 2001 From: Radim Krčmář Date: Wed, 1 Jul 2015 15:31:49 +0200 Subject: KVM: x86: make vapics_in_nmi_mode atomic Writes were a bit racy, but hard to turn into a bug at the same time. (Particularly because modern Linux doesn't use this feature anymore.) Signed-off-by: Radim Krčmář [Actually the next patch makes it much, much easier to trigger the race so I'm including this one for stable@ as well. - Paolo] Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini --- arch/x86/kvm/i8254.c | 2 +- arch/x86/kvm/lapic.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) (limited to 'arch/x86/kvm') diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c index 4dce6f8b6129..f90952f64e79 100644 --- a/arch/x86/kvm/i8254.c +++ b/arch/x86/kvm/i8254.c @@ -305,7 +305,7 @@ static void pit_do_work(struct kthread_work *work) * LVT0 to NMI delivery. Other PIC interrupts are just sent to * VCPU0, and only if its LVT0 is in EXTINT mode. */ - if (kvm->arch.vapics_in_nmi_mode > 0) + if (atomic_read(&kvm->arch.vapics_in_nmi_mode) > 0) kvm_for_each_vcpu(i, vcpu, kvm) kvm_apic_nmi_wd_deliver(vcpu); } diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 36e9de1b4127..607a56b35327 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -1263,10 +1263,10 @@ static void apic_manage_nmi_watchdog(struct kvm_lapic *apic, u32 lvt0_val) if (!nmi_wd_enabled) { apic_debug("Receive NMI setting on APIC_LVT0 " "for cpu %d\n", apic->vcpu->vcpu_id); - apic->vcpu->kvm->arch.vapics_in_nmi_mode++; + atomic_inc(&apic->vcpu->kvm->arch.vapics_in_nmi_mode); } } else if (nmi_wd_enabled) - apic->vcpu->kvm->arch.vapics_in_nmi_mode--; + atomic_dec(&apic->vcpu->kvm->arch.vapics_in_nmi_mode); } static int apic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val) -- cgit v1.2.3-55-g7522