[PATCH] KVM: vmx: expose more information for KVM_INTERNAL_ERROR_DELIVERY_EV exits

[PATCH] KVM: vmx: expose more information for KVM_INTERNAL_ERROR_DELIVERY_EV exits

[Paolo Bonzini]

This exit ended up being reported, but the currently exposed data does not provide
much of a starting point for debugging.  In the reported case, the vmexit was
an EPT misconfiguration (MMIO access).  Let userspace report ethe exit qualification
and, if relevant, the GPA.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/vmx.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 6dcc4873e435..4be80c3ac24d 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -8408,9 +8408,15 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu)
 			exit_reason != EXIT_REASON_TASK_SWITCH)) {
 		vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
 		vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_DELIVERY_EV;
-		vcpu->run->internal.ndata = 2;
+		vcpu->run->internal.ndata = 3;
 		vcpu->run->internal.data[0] = vectoring_info;
 		vcpu->run->internal.data[1] = exit_reason;
+		vcpu->run->internal.data[2] = vcpu->arch.exit_qualification;
+		if (exit_reason == EXIT_REASON_EPT_MISCONFIG) {
+			vcpu->run->internal.ndata++;
+			vcpu->run->internal.data[3] =
+				vmcs_read64(GUEST_PHYSICAL_ADDRESS);
+		}
 		return 0;
 	}
 
-- 
1.8.3.1

Re: [PATCH] KVM: vmx: expose more information for KVM_INTERNAL_ERROR_DELIVERY_EV exits

[David Hildenbrand]

On 05.07.2017 12:38, Paolo Bonzini wrote:
> This exit ended up being reported, but the currently exposed data does not provide
> much of a starting point for debugging.  In the reported case, the vmexit was
> an EPT misconfiguration (MMIO access).  Let userspace report ethe exit qualification
> and, if relevant, the GPA.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  arch/x86/kvm/vmx.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 6dcc4873e435..4be80c3ac24d 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -8408,9 +8408,15 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu)
>  			exit_reason != EXIT_REASON_TASK_SWITCH)) {
>  		vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
>  		vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_DELIVERY_EV;
> -		vcpu->run->internal.ndata = 2;
> +		vcpu->run->internal.ndata = 3;
>  		vcpu->run->internal.data[0] = vectoring_info;
>  		vcpu->run->internal.data[1] = exit_reason;
> +		vcpu->run->internal.data[2] = vcpu->arch.exit_qualification;
> +		if (exit_reason == EXIT_REASON_EPT_MISCONFIG) {
> +			vcpu->run->internal.ndata++;
> +			vcpu->run->internal.data[3] =
> +				vmcs_read64(GUEST_PHYSICAL_ADDRESS);

vcpu->run->internal.data[vcpu->run->internal.ndata++] = ...

So we don't have to name the position explicitly.

Whatever you prefer.

Reviewed-by: David Hildenbrand <david@redhat.com>

> +		}
>  		return 0;
>  	}
>  
> 


-- 

Thanks,

David

Re: [PATCH] KVM: vmx: expose more information for KVM_INTERNAL_ERROR_DELIVERY_EV exits

[Paolo Bonzini]

On 05/07/2017 14:25, David Hildenbrand wrote:
>>  		vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_DELIVERY_EV;
>> -		vcpu->run->internal.ndata = 2;
>> +		vcpu->run->internal.ndata = 3;
>>  		vcpu->run->internal.data[0] = vectoring_info;
>>  		vcpu->run->internal.data[1] = exit_reason;
>> +		vcpu->run->internal.data[2] = vcpu->arch.exit_qualification;
>> +		if (exit_reason == EXIT_REASON_EPT_MISCONFIG) {
>> +			vcpu->run->internal.ndata++;
>> +			vcpu->run->internal.data[3] =
>> +				vmcs_read64(GUEST_PHYSICAL_ADDRESS);
> vcpu->run->internal.data[vcpu->run->internal.ndata++] = ...

I considered that, but it's very long and the initializations above use
numbers.  Considering that this is not going to change very often, I
ended up with the hard coded 3.

Paolo

> So we don't have to name the position explicitly.
> 
> Whatever you prefer.
> 
> Reviewed-by: David Hildenbrand <david@redhat.com>
>