Messages in this thread | | | Date | Tue, 15 Mar 2022 11:35:35 -0300 | From | Jason Gunthorpe <> | Subject | Re: [PATCH v2 5/8] iommu: Add PASID support for DMA mapping API users |
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On Mon, Mar 14, 2022 at 10:07:09PM -0700, Jacob Pan wrote: > DMA mapping API is the de facto standard for in-kernel DMA. It operates > on a per device/RID basis which is not PASID-aware. > > Some modern devices such as Intel Data Streaming Accelerator, PASID is > required for certain work submissions. To allow such devices use DMA > mapping API, we need the following functionalities: > 1. Provide device a way to retrieve a PASID for work submission within > the kernel > 2. Enable the kernel PASID on the IOMMU for the device > 3. Attach the kernel PASID to the device's default DMA domain, let it > be IOVA or physical address in case of pass-through. > > This patch introduces a driver facing API that enables DMA API > PASID usage. Once enabled, device drivers can continue to use DMA APIs as > is. There is no difference in dma_handle between without PASID and with > PASID. > > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> > drivers/iommu/dma-iommu.c | 65 +++++++++++++++++++++++++++++++++++++++ > include/linux/dma-iommu.h | 7 +++++ > include/linux/iommu.h | 9 ++++++ > 3 files changed, 81 insertions(+) > > diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c > index b22034975301..d0ff1a34b1b6 100644 > +++ b/drivers/iommu/dma-iommu.c > @@ -39,6 +39,8 @@ enum iommu_dma_cookie_type { > IOMMU_DMA_MSI_COOKIE, > }; > > +static DECLARE_IOASID_SET(iommu_dma_pasid); > + > struct iommu_dma_cookie { > enum iommu_dma_cookie_type type; > union { > @@ -370,6 +372,69 @@ void iommu_put_dma_cookie(struct iommu_domain *domain) > domain->iova_cookie = NULL; > } > > +/** > + * iommu_enable_pasid_dma --Enable in-kernel DMA request with PASID > + * @dev: Device to be enabled > + * > + * DMA request with PASID will be mapped the same way as the legacy DMA. > + * If the device is in pass-through, PASID will also pass-through. If the > + * device is in IOVA map, the supervisor PASID will point to the same IOVA > + * page table. > + * > + * @return the kernel PASID to be used for DMA or INVALID_IOASID on failure > + */ > +int iommu_enable_pasid_dma(struct device *dev, ioasid_t *pasid) > +{ > + struct iommu_domain *dom; > + ioasid_t id, max; > + int ret; > + > + dom = iommu_get_domain_for_dev(dev); > + if (!dom || !dom->ops || !dom->ops->attach_dev_pasid) > + return -ENODEV;
Given the purpose of this API I think it should assert that the device has the DMA API in-use using the machinery from the other series.
ie this should not be used to clone non-DMA API iommu_domains..
> diff --git a/include/linux/dma-iommu.h b/include/linux/dma-iommu.h > index 24607dc3c2ac..e6cb9b52a420 100644 > +++ b/include/linux/dma-iommu.h > @@ -18,6 +18,13 @@ int iommu_get_dma_cookie(struct iommu_domain *domain); > int iommu_get_msi_cookie(struct iommu_domain *domain, dma_addr_t base); > void iommu_put_dma_cookie(struct iommu_domain *domain); > > +/* > + * For devices that can do DMA request with PASID, setup a system PASID. > + * Address modes (IOVA, PA) are selected by the platform code. > + */ > +int iommu_enable_pasid_dma(struct device *dev, ioasid_t *pasid); > +void iommu_disable_pasid_dma(struct device *dev, ioasid_t pasid);
The functions already have a kdoc, don't need two..
Jason
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