Re: [PATCH] target/i386/kvm: call kvm_put_vcpu_events() before kvm_put_nested_state()

[Eiichi Tsukata]

Hi all, appreciate any comments or feedbacks on the patch.

Thanks,
Eiichi

> On Nov 1, 2023, at 23:04, Vitaly Kuznetsov <vkuznets@redhat.com> wrote:
> 
> Eiichi Tsukata <eiichi.tsukata@nutanix.com> writes:
> 
>> FYI: The EINVAL in vmx_set_nested_state() is caused by the following 
>> condition:
>> * vcpu->arch.hflags == 0
>> * kvm_state->hdr.vmx.smm.flags == KVM_STATE_NESTED_SMM_VMXON
> 
> This is a weird state indeed,
> 
> 'vcpu->arch.hflags == 0' means we're not in SMM and not in guest mode
> but kvm_state->hdr.vmx.smm.flags == KVM_STATE_NESTED_SMM_VMXON is a
> reflection of vmx->nested.smm.vmxon (see
> vmx_get_nested_state()). vmx->nested.smm.vmxon gets set (conditioally)
> in vmx_enter_smm() and gets cleared in vmx_leave_smm() which means the
> vCPU must be in SMM to have it set.
> 
> In case the vCPU is in SMM upon migration, HF_SMM_MASK must be set from
> kvm_vcpu_ioctl_x86_set_vcpu_events() -> kvm_smm_changed() but QEMU's
> kvm_put_vcpu_events() calls kvm_put_nested_state() _before_
> kvm_put_vcpu_events(). This can explain "vcpu->arch.hflags == 0".
> 
> Paolo, Max, any idea how this is supposed to work?
> 
> -- 
> Vitaly
>