linux-kernel - Re: [PATCH v5 09/12] x86/kvm/nVMX: allow bare VMXON state migration

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Date:   Mon, 15 Oct 2018 19:09:35 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>, kvm@...r.kernel.org
Cc:     Radim Krčmář <rkrcmar@...hat.com>,
        Roman Kagan <rkagan@...tuozzo.com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        "Michael Kelley (EOSG)" <Michael.H.Kelley@...rosoft.com>,
        Jim Mattson <jmattson@...gle.com>,
        Liran Alon <liran.alon@...cle.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 09/12] x86/kvm/nVMX: allow bare VMXON state migration

On 13/09/2018 19:05, Vitaly Kuznetsov wrote:
> It is perfectly valid for a guest to do VMXON and not do VMPTRLD. This
> state needs to be preserved on migration.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>

Please cover this in state-test.c too.

Paolo

> ---
>  arch/x86/kvm/vmx.c | 15 ++++++++-------
>  1 file changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index d3297fadf7ed..25a25fff8dd9 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -14482,13 +14482,6 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
>  	if (!page_address_valid(vcpu, kvm_state->vmx.vmxon_pa))
>  		return -EINVAL;
>  
> -	if (kvm_state->size < sizeof(kvm_state) + sizeof(*vmcs12))
> -		return -EINVAL;
> -
> -	if (kvm_state->vmx.vmcs_pa == kvm_state->vmx.vmxon_pa ||
> -	    !page_address_valid(vcpu, kvm_state->vmx.vmcs_pa))
> -		return -EINVAL;
> -
>  	if ((kvm_state->vmx.smm.flags & KVM_STATE_NESTED_SMM_GUEST_MODE) &&
>  	    (kvm_state->flags & KVM_STATE_NESTED_GUEST_MODE))
>  		return -EINVAL;
> @@ -14510,6 +14503,14 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
>  	if (ret)
>  		return ret;
>  
> +	/* Empty 'VMXON' state is permitted */
> +	if (kvm_state->size < sizeof(kvm_state) + sizeof(*vmcs12))
> +		return 0;
> +
> +	if (kvm_state->vmx.vmcs_pa == kvm_state->vmx.vmxon_pa ||
> +	    !page_address_valid(vcpu, kvm_state->vmx.vmcs_pa))
> +		return -EINVAL;
> +
>  	set_current_vmptr(vmx, kvm_state->vmx.vmcs_pa);
>  
>  	if (kvm_state->vmx.smm.flags & KVM_STATE_NESTED_SMM_VMXON) {
>