linux-kernel - Re: [PATCH 1/2] KVM: VMX: Inject #GP on ENCLS if vCPU has paging disabled (CR0.PG==0)

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Date:   Thu, 6 Apr 2023 08:54:52 +0000
From:   "Huang, Kai" <kai.huang@...el.com>
To:     "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "Christopherson,, Sean" <seanjc@...gle.com>
CC:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "binbin.wu@...ux.intel.com" <binbin.wu@...ux.intel.com>
Subject: Re: [PATCH 1/2] KVM: VMX: Inject #GP on ENCLS if vCPU has paging
 disabled (CR0.PG==0)

On Wed, 2023-04-05 at 16:45 -0700, Sean Christopherson wrote:
> Inject a #GP when emulating/forwarding a valid ENCLS leaf if the vCPU has
> paging disabled, e.g. if KVM is intercepting ECREATE to enforce additional
> restrictions.  The pseudocode in the SDM lists all #GP triggers, including
> CR0.PG=0, as being checked after the ENLCS-exiting checks, i.e. the
> VM-Exit will occur before the CPU performs the CR0.PG check.
> 
> Fixes: 70210c044b4e ("KVM: VMX: Add SGX ENCLS[ECREATE] handler to enforce CPUID restrictions")
> Cc: Binbin Wu <binbin.wu@...ux.intel.com>
> Cc: Kai Huang <kai.huang@...el.com>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>

Reviewed-by: Kai Huang <kai.huang@...el.com>

> ---
>  arch/x86/kvm/vmx/sgx.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/vmx/sgx.c b/arch/x86/kvm/vmx/sgx.c
> index aa53c98034bf..f881f6ff6408 100644
> --- a/arch/x86/kvm/vmx/sgx.c
> +++ b/arch/x86/kvm/vmx/sgx.c
> @@ -375,7 +375,7 @@ int handle_encls(struct kvm_vcpu *vcpu)
>  
>  	if (!encls_leaf_enabled_in_guest(vcpu, leaf)) {
>  		kvm_queue_exception(vcpu, UD_VECTOR);
> -	} else if (!sgx_enabled_in_guest_bios(vcpu)) {
> +	} else if (!sgx_enabled_in_guest_bios(vcpu) || !is_paging(vcpu)) {
>  		kvm_inject_gp(vcpu, 0);
>  	} else {
>  		if (leaf == ECREATE)
> -- 
> 2.40.0.348.gf938b09366-goog
>