Hi, On 2/12/19 3:28 AM, Matthew Wilcox wrote:
I'm looking at commit 562831747f6299abd481b5b00bd4fa19d5c8a259 which fails to adequately explain why we can't use PASID 0. Commit af39507305fb83a5d3c475c2851f4d59545d8a18 also doesn't explain why PASID 0 is no longer usable for the intel-svm driver.
Sorry that we didn't make it clear.
There are a load of simplifications that could be made to this, but I don't know which ones to suggest without a clear understanding of the problem you're actually trying to solve.
PASID 0 has been reserved by Intel IOMMU driver for RID_PASID purpose. VT-d scalable mode treats all address translation as PASID granularity. For DMA requests-with-PASID, the PASID value in the DMA request will be used. For DMA requests-without-PASID, VT-d will use a static PASID value specified in the RID_PASID field of the context entry. PASID 0 has been reserved for this usage for all devices. (Please refer to 9.4 of the spec 3.0 for more details.) Best regards, Lu Baolu _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
