Messages in this thread |  | | Subject | Re: [PATCH v3 4/6] iommu/vt-d: Setup pasid entries for iova over first level | From | Lu Baolu <> | Date | Tue, 17 Dec 2019 10:03:41 +0800 |
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Hi Yi,
On 12/15/19 5:37 PM, Liu, Yi L wrote: >> XD (bit 63) is only for the first level, and SNP (bit 11) is only for second level, right? I >> think we need to always set XD bit for IOVA over FL case. thoughts? > Oops, I made a mistake here. Please forget SNP bit, there is no way to control SNP > with first level page table.:-) > > Actually, it is execute (bit 1) of second level page table which I wanted to say. > If software sets R/W/X permission to an IOVA, with IOVA over second level > page table, it will set bit 1. However, if IOVA is over first level page table, it > may need to clear XD bit. This is what I want to say here. If IOVA doesn’t allow > execute permission, it's ok to always set XD bit for IOVA over FL case. But I > would like to do it just as what we did for R/W permission. R/W permission > relies on the permission configured by the page map caller. right?
Got your point.
Current driver always cleard X (bit 2) in the second level page table. So we will always set XD bit (bit 63) in the first level page table. If we decide to use the X permission, we need a separated patch, right?
Best regards, baolu
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