Re: [PATCH 3/3] KVM: Cache pdptrs

[Avi Kivity <avi@redhat.com>]

Joerg Roedel wrote:
> On Mon, Jun 01, 2009 at 04:22:03PM +0300, Avi Kivity wrote:
>   
>> +static void svm_cache_reg(struct kvm_vcpu *vcpu, enum kvm_reg reg)
>> +{
>> +	switch (reg) {
>> +	case VCPU_EXREG_PDPTR:
>> +		BUG_ON(!npt_enabled);
>> +		load_pdptrs(vcpu, vcpu->arch.cr3);
>> +		break;
>> +	default:
>> +		BUG();
>> +	}
>> +}
>>     
>
> Don't we need to check for the return value of load_pdptrs() here and inject
> a #GP it it fails?
>   

We're after some random exit, the guest won't be expecting a #GP in some 
random instruction.

The only options are ignore and triple fault.

>> +
>>  static void svm_set_vintr(struct vcpu_svm *svm)
>>  {
>>  	svm->vmcb->control.intercept |= 1ULL << INTERCEPT_VINTR;
>> @@ -2286,12 +2298,6 @@ static int handle_exit(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
>>  		}
>>  		vcpu->arch.cr0 = svm->vmcb->save.cr0;
>>  		vcpu->arch.cr3 = svm->vmcb->save.cr3;
>> -		if (is_paging(vcpu) && is_pae(vcpu) && !is_long_mode(vcpu)) {
>> -			if (!load_pdptrs(vcpu, vcpu->arch.cr3)) {
>> -				kvm_inject_gp(vcpu, 0);
>> -				return 1;
>> -			}
>> -		}
>>     
>
> ... as done here.

That's a bug... luckily no guests trash their PDPTs after loading CR3.

I guess I should fix in a separate patch to avoid mixing a bugfix with a 
feature.

-- 
error compiling committee.c: too many arguments to function