> -----Original Message----- > From: Tian, Kevin [mailto:[email protected]] > Sent: Thursday, March 18, 2021 4:56 PM > To: Longpeng (Mike, Cloud Infrastructure Service Product Dept.) > <[email protected]>; Nadav Amit <[email protected]> > Cc: chenjiashang <[email protected]>; David Woodhouse > <[email protected]>; [email protected]; LKML > <[email protected]>; [email protected]; Gonglei (Arei) > <[email protected]>; [email protected] > Subject: RE: A problem of Intel IOMMU hardware ？ > > > From: Longpeng (Mike, Cloud Infrastructure Service Product Dept.) > > <[email protected]> > > > > > -----Original Message----- > > > From: Tian, Kevin [mailto:[email protected]] > > > Sent: Thursday, March 18, 2021 4:27 PM > > > To: Longpeng (Mike, Cloud Infrastructure Service Product Dept.) > > > <[email protected]>; Nadav Amit <[email protected]> > > > Cc: chenjiashang <[email protected]>; David Woodhouse > > > <[email protected]>; [email protected]; LKML > > > <[email protected]>; [email protected]; Gonglei > > (Arei) > > > <[email protected]>; [email protected] > > > Subject: RE: A problem of Intel IOMMU hardware ？ > > > > > > > From: iommu <[email protected]> On Behalf > > > > Of Longpeng (Mike, Cloud Infrastructure Service Product Dept.) > > > > > > > > > 2. Consider ensuring that the problem is not somehow related to > > > > > queued invalidations. Try to use __iommu_flush_iotlb() instead > > > > > of > > > qi_flush_iotlb(). > > > > > > > > > > > > > I tried to force to use __iommu_flush_iotlb(), but maybe something > > > > wrong, the system crashed, so I prefer to lower the priority of > > > > this > > operation. > > > > > > > > > > The VT-d spec clearly says that register-based invalidation can be > > > used only > > when > > > queued-invalidations are not enabled. Intel-IOMMU driver doesn't > > > provide > > an > > > option to disable queued-invalidation though, when the hardware is > > capable. If you > > > really want to try, tweak the code in intel_iommu_init_qi. > > > > > > > Hi Kevin, > > > > Thanks to point out this. Do you have any ideas about this problem ? I > > tried to descript the problem much clear in my reply to Alex, hope you > > could have a look if you're interested. > > > > btw I saw you used 4.18 kernel in this test. What about latest kernel? >
Not test yet. It's hard to upgrade kernel in our environment. > Also one way to separate sw/hw bug is to trace the low level interface (e.g., > qi_flush_iotlb) which actually sends invalidation descriptors to the IOMMU > hardware. Check the window between b) and c) and see whether the software does > the right thing as expected there. > We add some log in iommu driver these days, the software seems fine. But we didn't look inside the qi_submit_sync yet, I'll try it tonight. > Thanks > Kevin
