Re: [PATCH 4/4] vfio: Allow type-1 IOMMU instantiation with a virtio-iommu

[Jean-Philippe Brucker <jean-philippe.brucker@arm.com>]

On 14/02/18 15:35, Robin Murphy wrote:
> On 14/02/18 15:26, Alex Williamson wrote:
>> On Wed, 14 Feb 2018 14:53:40 +0000
>> Jean-Philippe Brucker <jean-philippe.brucker@arm.com> wrote:
>>
>>> When enabling both VFIO and VIRTIO_IOMMU modules, automatically select
>>> VFIO_IOMMU_TYPE1 as well.
>>>
>>> Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
>>> ---
>>>   drivers/vfio/Kconfig | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/vfio/Kconfig b/drivers/vfio/Kconfig
>>> index c84333eb5eb5..65a1e691110c 100644
>>> --- a/drivers/vfio/Kconfig
>>> +++ b/drivers/vfio/Kconfig
>>> @@ -21,7 +21,7 @@ config VFIO_VIRQFD
>>>   menuconfig VFIO
>>>   	tristate "VFIO Non-Privileged userspace driver framework"
>>>   	depends on IOMMU_API
>>> -	select VFIO_IOMMU_TYPE1 if (X86 || S390 || ARM_SMMU || ARM_SMMU_V3)
>>> +	select VFIO_IOMMU_TYPE1 if (X86 || S390 || ARM_SMMU || ARM_SMMU_V3 || VIRTIO_IOMMU)
>>>   	select ANON_INODES
>>>   	help
>>>   	  VFIO provides a framework for secure userspace device drivers.
>>
>> Why are we basing this on specific IOMMU drivers in the first place?
>> Only ARM is doing that.  Shouldn't IOMMU_API only be enabled for ARM
>> targets that support it and therefore we can forget about the specific
>> IOMMU drivers?  Thanks,
> 
> Makes sense - the majority of ARM systems (and mobile/embedded ARM64 
> ones) making use of IOMMU_API won't actually support VFIO, but it can't 
> hurt to allow them to select the type 1 driver regardless. Especially as 
> multiplatform configs are liable to be pulling in the SMMU driver(s) anyway.

Cool, then I'll change that line to:

+	select VFIO_IOMMU_TYPE1 if (X86 || S390 || ARM || ARM64)

Thanks,
Jean