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    SubjectRe: [PATCH v2 0/8] Enable PASID for DMA API users
    Hi Kevin,

    On Tue, 15 Mar 2022 08:16:59 +0000, "Tian, Kevin" <kevin.tian@intel.com>
    wrote:

    > > From: Jacob Pan <jacob.jun.pan@linux.intel.com>
    > > Sent: Tuesday, March 15, 2022 1:07 PM
    > >
    > > Some modern accelerators such as Intel's Data Streaming Accelerator
    > > (DSA) require PASID in DMA requests to be operational. Specifically,
    > > the work submissions with ENQCMD on shared work queues require PASIDs.
    > > The use cases
    > > include both user DMA with shared virtual addressing (SVA) and in-kernel
    > > DMA similar to legacy DMA w/o PASID. Here we address the latter.
    > >
    > > DMA mapping API is the de facto standard for in-kernel DMA. However, it
    > > operates on a per device or Requester ID(RID) basis which is not
    > > PASID-aware. To leverage DMA API for devices relies on PASIDs, this
    > > patchset introduces the following APIs
    > >
    > > 1. A driver facing API that enables DMA API PASID usage:
    > > iommu_enable_pasid_dma(struct device *dev, ioasid_t &pasid);
    >
    > Should this be called dma_enable_pasid() since it's about DMA API? Doing
    > so also avoids the driver to include iommu.h.
    >
    PASID is still tied to IOMMU, drivers who wants to use this must explicitly
    put dependency on IOMMU. So I prefer not to give that illusion.

    > Thanks
    > Kevin


    Thanks,

    Jacob

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