From: Maxim Levitsky Date: Mon, 6 Jun 2022 18:08:27 +0000 (+0300) Subject: KVM: x86: disable preemption while updating apicv inhibition X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=66c768d30e64e1280520f34dbef83419f55f3459;p=linux.git KVM: x86: disable preemption while updating apicv inhibition Currently nothing prevents preemption in kvm_vcpu_update_apicv. On SVM, If the preemption happens after we update the vcpu->arch.apicv_active, the preemption itself will 'update' the inhibition since the AVIC will be first disabled on vCPU unload and then enabled, when the current task is loaded again. Then we will try to update it again, which will lead to a warning in __avic_vcpu_load, that the AVIC is already enabled. Fix this by disabling preemption in this code. Signed-off-by: Maxim Levitsky Message-Id: <20220606180829.102503-6-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 03fbfbbec460f..158b2e135efce 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -9850,6 +9850,7 @@ void kvm_vcpu_update_apicv(struct kvm_vcpu *vcpu) return; down_read(&vcpu->kvm->arch.apicv_update_lock); + preempt_disable(); activate = kvm_vcpu_apicv_activated(vcpu); @@ -9870,6 +9871,7 @@ void kvm_vcpu_update_apicv(struct kvm_vcpu *vcpu) kvm_make_request(KVM_REQ_EVENT, vcpu); out: + preempt_enable(); up_read(&vcpu->kvm->arch.apicv_update_lock); } EXPORT_SYMBOL_GPL(kvm_vcpu_update_apicv);