Messages in this thread | | | Subject | Re: [PATCH 2/4] iommu: Add PASID support for DMA mapping API users | From | Lu Baolu <> | Date | Wed, 8 Dec 2021 10:31:36 +0800 |
| |
Hi Jacob,
On 12/7/21 9:47 PM, 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 kernel PASID for work submission > 2. Enable the kernel PASID on the IOMMU > 3. Establish address space for the kernel PASID that matches the default > 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.
Can a device issue DMA requests with PASID even there's no system IOMMU or the system IOMMU is disabled?
Best regards, baolu
| |