Re: [PATCH] KVM: nVMX: Allow restore nested-state to enable eVMCS when vCPU in SMM

[Vitaly Kuznetsov <vkuznets@redhat.com>]

Liran Alon <liran.alon@oracle.com> writes:

> As comment in code specifies, SMM temporarily disables VMX so we cannot
> be in guest mode, nor can VMLAUNCH/VMRESUME be pending.
>
> However, code currently assumes that these are the only flags that can be
> set on kvm_state->flags. This is not true as KVM_STATE_NESTED_EVMCS
> can also be set on this field to signal that eVMCS should be enabled.
>
> Therefore, fix code to check for guest-mode and pending VMLAUNCH/VMRESUME
> explicitly.
>
> Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
> Signed-off-by: Liran Alon <liran.alon@oracle.com>
> ---
>  arch/x86/kvm/vmx/nested.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index 5c470db311f7..27ff04874f67 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -5373,7 +5373,10 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
>  	 * nor can VMLAUNCH/VMRESUME be pending.  Outside SMM, SMM flags
>  	 * must be zero.
>  	 */
> -	if (is_smm(vcpu) ? kvm_state->flags : kvm_state->hdr.vmx.smm.flags)
> +	if (is_smm(vcpu) ?
> +		(kvm_state->flags &
> +		 (KVM_STATE_NESTED_GUEST_MODE | KVM_STATE_NESTED_RUN_PENDING))
> +		: kvm_state->hdr.vmx.smm.flags)
>  		return -EINVAL;
>  
>  	if ((kvm_state->hdr.vmx.smm.flags & KVM_STATE_NESTED_SMM_GUEST_MODE) &&

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>

-- 
Vitaly