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SubjectRe: [RFC PATCH 1/5] iommu: Add APIs for IOMMU PASID management
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Hi,

On 12/16/18 6:38 AM, Liu, Yi L wrote:
>> From: Lu Baolu [mailto:baolu.lu@linux.intel.com]
>> Sent: Sunday, November 11, 2018 10:45 PM
>> Subject: [RFC PATCH 1/5] iommu: Add APIs for IOMMU PASID management
>>
>> This adds APIs for IOMMU drivers and device drivers to manage the PASIDs used for
>> DMA transfer and translation. It bases on I/O ASID allocator for PASID namespace
>> management and relies on vendor specific IOMMU drivers for paravirtual PASIDs.
>>
>> Below APIs are added:
>>
>> * iommu_pasid_init(pasid)
>> - Initialize a PASID consumer. The vendor specific IOMMU
>> drivers are able to set the PASID range imposed by IOMMU
>> hardware through a callback in iommu_ops.
>>
>> * iommu_pasid_exit(pasid)
>> - The PASID consumer stops consuming any PASID.
>>
>> * iommu_pasid_alloc(pasid, min, max, private, *ioasid)
>> - Allocate a PASID and associate a @private data with this
>> PASID. The PASID value is stored in @ioaisd if returning
>> success.
>>
>> * iommu_pasid_free(pasid, ioasid)
>> - Free a PASID to the pool so that it could be consumed by
>> others.
>>
>> This also adds below helpers to lookup or iterate PASID items associated with a
>> consumer.
>>
>> * iommu_pasid_for_each(pasid, func, data)
>> - Iterate PASID items of the consumer identified by @pasid,
>> and call @func() against each item. An error returned from
>> @func() will break the iteration.
>>
>> * iommu_pasid_find(pasid, ioasid)
>> - Retrieve the private data associated with @ioasid.
>>
>> Cc: Ashok Raj <ashok.raj@intel.com>
>> Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
>> Cc: Kevin Tian <kevin.tian@intel.com>
>> Cc: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
>> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
>> ---
>> drivers/iommu/Kconfig | 1 +
>> drivers/iommu/iommu.c | 89 +++++++++++++++++++++++++++++++++++++++++++
>> include/linux/iommu.h | 73 +++++++++++++++++++++++++++++++++++
>> 3 files changed, 163 insertions(+)
>>
>> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig index
>> d9a25715650e..39f2bb76c7b8 100644
>> --- a/drivers/iommu/Kconfig
>> +++ b/drivers/iommu/Kconfig
>> @@ -1,6 +1,7 @@
>> # IOMMU_API always gets selected by whoever wants it.
>> config IOMMU_API
>> bool
>> + select IOASID
>>
>> menuconfig IOMMU_SUPPORT
>> bool "IOMMU Hardware Support"
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index
>> 0b7c96d1425e..570b244897bb 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -2082,3 +2082,92 @@ void iommu_detach_device_aux(struct iommu_domain
>> *domain, struct device *dev)
>> }
>> }
>> EXPORT_SYMBOL_GPL(iommu_detach_device_aux);
>> +
>> +/*
>> + * APIs for PASID used by IOMMU and the device drivers which depend
>> + * on IOMMU.
>> + */
>> +struct iommu_pasid *iommu_pasid_init(struct bus_type *bus) {
>
> I'm thinking about if using struct iommu_domain here is better
> than struct bus_type. The major purpose is to pass iommu_ops
> in it and route into iommu-sublayer. iommu_domain may be
> better since some modules like vfio_iommu_type1 would use
> iommu_domain more than bus type.

But drivers might call this during initialization when it doesn't has
any domain yet.

Best regards,
Lu Baolu

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