[PATCH v2 2/5] KVM: ARM: on IO mem abort - route the call to KVM MMIO bus

[eric.auger@linaro.org (Eric Auger)]

On 01/12/2015 06:09 PM, Eric Auger wrote:
> Hi Nikolay,
> On 12/07/2014 10:37 AM, Nikolay Nikolaev wrote:
>> On IO memory abort, try to handle the MMIO access thorugh the KVM
>> registered read/write callbacks. This is done by invoking the relevant
>> kvm_io_bus_* API.
>>
>> Signed-off-by: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
>> ---
>>  arch/arm/kvm/mmio.c |   33 +++++++++++++++++++++++++++++++++
>>  1 file changed, 33 insertions(+)
>>
>> diff --git a/arch/arm/kvm/mmio.c b/arch/arm/kvm/mmio.c
>> index 4cb5a93..e42469f 100644
>> --- a/arch/arm/kvm/mmio.c
>> +++ b/arch/arm/kvm/mmio.c
>> @@ -162,6 +162,36 @@ static int decode_hsr(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>>  	return 0;
>>  }
>>  
>> +/**
>> + * handle_kernel_mmio - handle an in-kernel MMIO access
>> + * @vcpu:	pointer to the vcpu performing the access
>> + * @run:	pointer to the kvm_run structure
>> + * @mmio:	pointer to the data describing the access
>> + *
>> + * returns true if the MMIO access has been performed in kernel space,
>> + * and false if it needs to be emulated in user space.
>> + */
>> +static bool handle_kernel_mmio(struct kvm_vcpu *vcpu, struct kvm_run *run,
>> +		struct kvm_exit_mmio *mmio)
>> +{
>> +	int ret;
>> +
>> +	if (mmio->is_write) {
>> +		ret = kvm_io_bus_write(vcpu, KVM_MMIO_BUS, mmio->phys_addr,
>> +				mmio->len, &mmio->data);
>> +
>> +	} else {
>> +		ret = kvm_io_bus_read(vcpu, KVM_MMIO_BUS, mmio->phys_addr,
>> +				mmio->len, &mmio->data);
>> +	}
>> +	if (!ret) {
>> +		kvm_prepare_mmio(run, mmio);
>> +		kvm_handle_mmio_return(vcpu, run);
>> +	}
>> +
>> +	return !ret;
> in case ret < 0 (-EOPNOTSUPP = -95) aren't we returning true too? return
> (ret==0)?
Please forget that comment ;-)
Eric
> 
>> +}
>> +
>>  int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
>>  		 phys_addr_t fault_ipa)
>>  {
>> @@ -200,6 +230,9 @@ int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
>>  	if (vgic_handle_mmio(vcpu, run, &mmio))
>>  		return 1;
>>  
>> +	if (handle_kernel_mmio(vcpu, run, &mmio))
>> +		return 1;
>> +
>>  	kvm_prepare_mmio(run, &mmio);
>>  	return 0;
> currently the io_mem_abort returned value is not used by mmu.c code. I
> think this should be handed in kvm_handle_guest_abort. What do you think?
> 
> Best Regards
> 
> Eric
>>  }
>>
>