On Wed, May 18, 2011 at 08:52:36AM +0300, Nadav Har'El wrote:
> On Tue, May 17, 2011, Marcelo Tosatti wrote about "Re: [PATCH 08/31] nVMX: Fix local_vcpus_link handling":
> > On Tue, May 17, 2011 at 10:30:30PM +0300, Nadav Har'El wrote:
> > > So we'll have two fields, vmx.vcpu.cpu and vmx.vmcs.cpu, which are supposed
> > > to always contain the same value. Are you fine with that?
> >
> > Yes. Avi?
>
> Oops, it's even worse than I said, because if the new vmclear_local_vmcss
> clears the vmcs currently used on some vcpu, it will update vmcs.cpu on that
> vcpu to -1, but will *not* update vmx.vcpu.cpu, which remain its old value,
> and potentially cause problems when it is used (e.g., in x86.c) instead
> of vmx.vmcs.cpu.
Humpf, right. OK, you can handle the x86.c usage with
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 64edf57..b5fd9b4 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2118,7 +2118,7 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
if (need_emulate_wbinvd(vcpu)) {
if (kvm_x86_ops->has_wbinvd_exit())
cpumask_set_cpu(cpu, vcpu->arch.wbinvd_dirty_mask);
- else if (vcpu->cpu != -1 && vcpu->cpu != cpu)
+ else if (vcpu->cpu != -1 && vcpu->cpu != cpu && cpu_online(vcpu->cpu))
smp_call_function_single(vcpu->cpu,
wbinvd_ipi, NULL, 1);
}
Note this is not just about the code being nicer, but simplicity is
crucial, the code is tricky enough with one linked list.
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