linux-kernel - RE: [Issue]platform/x86: iommu: System can't shutdown because iommu driver keeps checking the status of DMA_GSTS_TES

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Message-ID: <DM6PR19MB2636E5A28FB655C2F657FDF8FA640@DM6PR19MB2636.namprd19.prod.outlook.com>
Date:   Thu, 9 Jul 2020 20:58:19 +0000
From:   "Limonciello, Mario" <Mario.Limonciello@...l.com>
To:     Koba Ko <koba.ko@...onical.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>
CC:     "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        Kai Heng Feng <kai.heng.feng@...onical.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Christian Kellner <ckellner@...hat.com>
Subject: RE: [Issue]platform/x86: iommu: System can't shutdown because iommu
 driver keeps checking the status of DMA_GSTS_TES

> -----Original Message-----
> From: iommu <iommu-bounces@...ts.linux-foundation.org> On Behalf Of Koba Ko
> Sent: Sunday, June 14, 2020 10:47 PM
> To: David Woodhouse; Lu Baolu; Joerg Roedel
> Cc: iommu@...ts.linux-foundation.org; Kai Heng Feng; Linux Kernel Mailing
> List
> Subject: [Issue]platform/x86: iommu: System can't shutdown because iommu
> driver keeps checking the status of DMA_GSTS_TES
> 
> hi All,
> I have a machine and there's only intel gpu.
> the secureboot and vt-d is enabled in BIOS.
> On the Ubuntu desktop, I do s2idle first and restart the machine.
> The machine can't restart successfully, so I need to press the power
> button to shutdown.
> I tried  each of the following and the issue can't be triggered.
> 1. disable secure boot in BIOS.

Just to explain why this happens, on many of Dell's systems VT-d is only enabled
when secure boot is enabled.

> 2. intel_iommu=off.
> 3. intel_iomm=igfx_off.
> 4. nomodeset
> 5. i915.modeset=0.
> 
> After I investigate further, find inte_iommu keeps checking the status
> of DMA_GSTS_TES.
> During the procedure of restart, the driver would disable iommu translation
> and
> check the status of DMA_GSTS_TES until status of DMA_GSTS_TES is 0.
> 
> If you need more information, I can provide it.
> 
> Thanks
> Koba Ko
> _______________________________________________
> iommu mailing list
> iommu@...ts.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu

This is reported on TGL pre-production system, but actually same symptom is also
happening in ICL production systems such as XPS 7390 2-in-1 and XPS 9300.

Details for the ICL issue are available here:
https://bugzilla.kernel.org/show_bug.cgi?id=206571

A user did bisect it back to commit 6c3a44ed3c553c324845744f30bcd1d3b07d61fd in
5.5.  Glancing through the code and comparing the suspend case, I would ask is it
just a case of missing a flush at shutdown (IE iommu_flush_all)?

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