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

[Vitaly Kuznetsov]

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