Re: [PATCH] KVM: x86: fix access memslots w/o hold srcu read lock

[Wanpeng Li]

Hi Paolo,
On 14/10/31 äå6:36, Paolo Bonzini wrote:
> On 31/10/2014 06:30, Chen, Tiejun wrote:
> > @@ -4442,6 +4442,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu)
> >   {
> >          struct vcpu_vmx *vmx = to_vmx(vcpu);
> >          struct msr_data apic_base_msr;
> > +       int idx;
> >
> >          vmx->rmode.vm86_active = 0;
> >
> > @@ -4509,7 +4510,9 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu)
> >                  vmcs_write32(TPR_THRESHOLD, 0);
> >          }
> >
> > +       idx = srcu_read_lock(&vcpu->kvm->srcu);
> >          kvm_vcpu_reload_apic_access_page(vcpu);
> > +       srcu_read_unlock(&vcpu->kvm->srcu, idx);
> >
> >          if (vmx_vm_has_apicv(vcpu->kvm))
> >                  memset(&vmx->pi_desc, 0, sizeof(struct pi_desc));
> Not enough; you can call vcpu_enter_guest -> kvm_apic_accept_events ->
> kvm_vcpu_reset -> vmx_vcpu_reset while under the SRCU lock.  The right
> place to add the lock is kvm_arch_vcpu_setup.

This is also not enough. I see the warning in the below path during the 
test:

kvm_arch_vcpu_ioctl_run
-> kvm_apic_accept_events
-> kvm_vcpu_reset

I just send out the version 3 and hope it can take care all the 
situations. ;-)

Regards,
Wanpeng Li

> Thanks,
>
> Paolo
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