Messages in this thread Patch in this message | | | From | "Srivatsa S. Bhat" <> | Subject | [RFC PATCH v4 8/9] kvm, vmx: Add atomic synchronization with CPU Hotplug | Date | Tue, 11 Dec 2012 19:35:32 +0530 |
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preempt_disable() will no longer help prevent CPUs from going offline, once stop_machine() gets removed from the CPU offline path. So use get/put_online_cpus_atomic() in vmx_vcpu_load() to prevent CPUs from going offline while clearing vmcs.
Reported-by: Michael Wang <wangyun@linux.vnet.ibm.com> Debugged-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, 6 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index f858159..d8a4cf1 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -1519,10 +1519,14 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu) struct vcpu_vmx *vmx = to_vmx(vcpu); u64 phys_addr = __pa(per_cpu(vmxarea, cpu)); - if (!vmm_exclusive) + if (!vmm_exclusive) { kvm_cpu_vmxon(phys_addr); - else if (vmx->loaded_vmcs->cpu != cpu) + } else if (vmx->loaded_vmcs->cpu != cpu) { + /* Prevent any CPU from going offline */ + get_online_cpus_atomic(); loaded_vmcs_clear(vmx->loaded_vmcs); + put_online_cpus_atomic(); + } if (per_cpu(current_vmcs, cpu) != vmx->loaded_vmcs->vmcs) { per_cpu(current_vmcs, cpu) = vmx->loaded_vmcs->vmcs;
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