linux-kernel - RE: A problem of Intel IOMMU hardware ？

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Date:   Thu, 18 Mar 2021 08:27:12 +0000
From:   "Tian, Kevin" <kevin.tian@...el.com>
To:     "Longpeng (Mike, Cloud Infrastructure Service Product Dept.)" 
        <longpeng2@...wei.com>, Nadav Amit <nadav.amit@...il.com>
CC:     chenjiashang <chenjiashang@...wei.com>,
        David Woodhouse <dwmw2@...radead.org>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        "Gonglei (Arei)" <arei.gonglei@...wei.com>,
        "will@...nel.org" <will@...nel.org>
Subject: RE: A problem of Intel IOMMU hardware ？

> From: iommu <iommu-bounces@...ts.linux-foundation.org> 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.

Thanks
Kevin