Re: [PATCH v3 5/7] KVM: x86: VMX: Intercept #GP to support access to VMware backdoor ports

[Paolo Bonzini <pbonzini@xxxxxxxxxx>]

On 16/03/2018 16:51, Radim Krčmář wrote:
>> +	if (!vmx->rmode.vm86_active && is_gp_fault(intr_info)) {
> Do we have some guarantees that the backdoor ports are never going to be
> used while vmx->rmode.vm86_active?

While vmx->rmode.vm86_active, handle_rmode_exception simply runs the
emulator whenever it sees a #GP, so that works too (except for not
having EMULTYPE_NO_UD_ON_FAIL).

Paolo

> Thanks.
> 
>> +		WARN_ON_ONCE(!enable_vmware_backdoor);
>> +		er = emulate_instruction(vcpu,
>> +			EMULTYPE_VMWARE | EMULTYPE_NO_UD_ON_FAIL);
>> +		if (er == EMULATE_USER_EXIT)
>> +			return 0;
>> +		else if (er != EMULATE_DONE)
>> +			kvm_queue_exception_e(vcpu, GP_VECTOR, error_code);
>> +		return 1;
>> +	}