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Subject[RFC PATCH 07/10] KVM: VMX: fix invalid cpu passed to smp_call_function_single
Date
From: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>

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 <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
---

arch/x86/kvm/vmx.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index f858159..9dc562a 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)


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