linux-kernel - Re: [PATCH 15/18] KVM: MMU: Propagate the right fault back to the guest after gva_to

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Message-ID: <20100315125240.GD13108@8bytes.org>
Date:	Mon, 15 Mar 2010 13:52:40 +0100
From:	Joerg Roedel <joro@...tes.org>
To:	"Daniel K." <dk@...no>
Cc:	Joerg Roedel <joerg.roedel@....com>, Avi Kivity <avi@...hat.com>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	Alexander Graf <agraf@...e.de>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 15/18] KVM: MMU: Propagate the right fault back to the
	guest after gva_to_gpa

On Mon, Mar 15, 2010 at 04:30:47AM +0000, Daniel K. wrote:
> Joerg Roedel wrote:
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index 2883ce8..9f8b02d 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -314,6 +314,19 @@ void kvm_inject_page_fault(struct kvm_vcpu *vcpu, unsigned long addr,
>>  	kvm_queue_exception_e(vcpu, PF_VECTOR, error_code)
>>  }
>>  +void kvm_propagate_fault(struct kvm_vcpu *vcpu, unsigned long addr, 
>> u32 error_code)
>> +{
>> +	u32 nested, error;
>> +
>> +	nested = error_code &  PFERR_NESTED_MASK;
>> +	error  = error_code & ~PFERR_NESTED_MASK;
>> +
>> +	if (vcpu->arch.mmu.nested && !(error_code && PFERR_NESTED_MASK))
>
> This looks incorrect, nested is unused.
>
> At the very least it should be a binary & operation
>
> 	if (vcpu->arch.mmu.nested && !(error_code & PFERR_NESTED_MASK))
>
> which can be simplified to
>
> 	if (vcpu->arch.mmu.nested && !nested)
>
> but it seems wrong that the condition is that it is nested and not nested 
> at the same time.

Yes, this is already fixed in my local patch-stack. I found it during
further testing (while fixing another bug). But thanks for your feedback
:-)

	Joerg

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