From mboxrd@z Thu Jan 1 00:00:00 1970 From: Xiao Guangrong Subject: [PATCH 1/2] KVM: VMX: fix invalid cpu passed to smp_call_function_single Date: Wed, 28 Nov 2012 20:53:15 +0800 Message-ID: <50B6093B.7040404@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , Gleb Natapov , LKML , KVM To: Avi Kivity Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org In loaded_vmcs_clear, loaded_vmcs->cpu is the fist parameter passed to smp_call_function_single, if the target cpu is downing (doing cpu hot remove), loaded_vmcs->cpu can become -1 then -1 is passed to smp_call_function_single It can be triggered when vcpu is being destroyed, loaded_vmcs_clear is called in the preemptionable context Signed-off-by: Xiao Guangrong --- arch/x86/kvm/vmx.c | 8 +++++--- 1 files changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 6599e45..29e8f42 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -1007,9 +1007,11 @@ static void __loaded_vmcs_clear(void *arg) static void loaded_vmcs_clear(struct loaded_vmcs *loaded_vmcs) { - if (loaded_vmcs->cpu != -1) - smp_call_function_single( - loaded_vmcs->cpu, __loaded_vmcs_clear, loaded_vmcs, 1); + int cpu = loaded_vmcs->cpu; + + if (cpu != -1) + smp_call_function_single(cpu, + __loaded_vmcs_clear, loaded_vmcs, 1); } static inline void vpid_sync_vcpu_single(struct vcpu_vmx *vmx) -- 1.7.7.6