[MODERATED] Re: ***UNCHECKED*** Re: Re: [PATCH v7 3/5] NX 3

[Paolo Bonzini <pbonzini@redhat.com>]

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On 25/10/19 11:45, speck for Joerg Roedel wrote:
> On Fri, Oct 25, 2019 at 11:08:25AM +0200, speck for Paolo Bonzini wrote:
>> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
>> index e7970a2e8eae..8979d5e7b6f5 100644
>> --- a/arch/x86/kvm/vmx/vmx.c
>> +++ b/arch/x86/kvm/vmx/vmx.c
>> @@ -969,17 +969,9 @@ static bool update_transition_efer(struct vcpu_vmx *vmx, int efer_offset)
>>  	u64 guest_efer = vmx->vcpu.arch.efer;
>>  	u64 ignore_bits = 0;
>>  
>> -	if (!enable_ept) {
>> -		/*
>> -		 * NX is needed to handle CR0.WP=1, CR4.SMEP=1.  Testing
>> -		 * host CPUID is more efficient than testing guest CPUID
>> -		 * or CR4.  Host SMEP is anyway a requirement for guest SMEP.
>> -		 */
>> -		if (boot_cpu_has(X86_FEATURE_SMEP))
>> -			guest_efer |= EFER_NX;
>> -		else if (!(guest_efer & EFER_NX))
>> -			ignore_bits |= EFER_NX;
>> -	}
>> +	/* Shadow paging assumes the NX bit to be available.  */
>> +	if (!enable_ept)
>> +		guest_efer |= EFER_NX;
>>  
>>  	/*
>>  	 * LMA and LME handled by hardware; SCE meaningless outside long mode.
> 
> Works with ept on and off, thanks.

Thanks, I'll include also the AMD version in a new patch and send it out as v8:

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 4153ca8cddb7..29feb3ecc91c 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -739,8 +739,12 @@ static int get_npt_level(struct kvm_vcpu *vcpu)
 static void svm_set_efer(struct kvm_vcpu *vcpu, u64 efer)
 {
 	vcpu->arch.efer = efer;
-	if (!npt_enabled && !(efer & EFER_LMA))
-		efer &= ~EFER_LME;
+	if (!npt_enabled) {
+		/* Shadow paging assumes the NX bit to be available.  */
+		efer |= EFER_NXE;
+		if (!(efer & EFER_LMA))
+			efer &= ~EFER_LME;
+	}
 
 	to_svm(vcpu)->vmcb->save.efer = efer | EFER_SVME;
 	mark_dirty(to_svm(vcpu)->vmcb, VMCB_CR);

Paolo