Once stop_machine() is gone from the CPU offline path, we won't be able to depend on preempt_disable() or local_irq_disable() to prevent CPUs from going offline from under us.
Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going offline, while invoking from atomic context (in vmx_vcpu_load() to prevent CPUs from going offline while clearing vmcs). Reported-by: Michael Wang <[email protected]> Debugged-by: Xiao Guangrong <[email protected]> Cc: Marcelo Tosatti <[email protected]> Cc: Gleb Natapov <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: [email protected] Cc: [email protected] Signed-off-by: Srivatsa S. Bhat <[email protected]> --- 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 9120ae1..2886ff0 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -1557,10 +1557,14 @@ 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; _______________________________________________ Linuxppc-dev mailing list [email protected] https://lists.ozlabs.org/listinfo/linuxppc-dev
