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
