linux-kernel - Re: [PATCH] KVM: VMX: Resume guest immediately when injecting #GP on ECREATE

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Date:   Mon, 3 Oct 2022 01:01:18 +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>
Subject: Re: [PATCH] KVM: VMX: Resume guest immediately when injecting #GP on
 ECREATE

On Fri, 2022-09-30 at 23:31 +0000, Sean Christopherson wrote:
> Resume the guest immediately when injecting a #GP on ECREATE due to an
> invalid enclave size, i.e. don't attempt ECREATE in the host.  The #GP is
> a terminal fault, e.g. skipping the instruction if ECREATE is successful
> would result in KVM injecting #GP on the instruction following ECREATE.
> 
> Fixes: 70210c044b4e ("KVM: VMX: Add SGX ENCLS[ECREATE] handler to enforce CPUID restrictions")
> Cc: stable@...r.kernel.org
> Cc: Kai Huang <kai.huang@...el.com>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
> 
> Effectively compile tested only, found by inspection when auditing use of
> kvm_skip_emulated_instruction().
> 
>  arch/x86/kvm/vmx/sgx.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/vmx/sgx.c b/arch/x86/kvm/vmx/sgx.c
> index 8f95c7c01433..b12da2a6dec9 100644
> --- a/arch/x86/kvm/vmx/sgx.c
> +++ b/arch/x86/kvm/vmx/sgx.c
> @@ -182,8 +182,10 @@ static int __handle_encls_ecreate(struct kvm_vcpu *vcpu,
>  	/* Enforce CPUID restriction on max enclave size. */
>  	max_size_log2 = (attributes & SGX_ATTR_MODE64BIT) ? sgx_12_0->edx >> 8 :
>  							    sgx_12_0->edx;
> -	if (size >= BIT_ULL(max_size_log2))
> +	if (size >= BIT_ULL(max_size_log2)) {
>  		kvm_inject_gp(vcpu, 0);
> +		return 1;
> +	}
>  
>  	/*
>  	 * sgx_virt_ecreate() returns:
> 
> base-commit: c59fb127583869350256656b7ed848c398bef879
> -- 
> 2.38.0.rc1.362.ged0d419d3c-goog
> 


Thanks Sean.

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

-- 
Thanks,
-Kai