Bug 177791 - screen flickering with intel_iommu=on
Summary: screen flickering with intel_iommu=on
Status: RESOLVED INSUFFICIENT_DATA
Alias: None
Product: Virtualization
Classification: Unclassified
Component: kvm (show other bugs)
Hardware: Intel Linux
: P1 low
Assignee: virtualization_kvm
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2016-10-17 04:14 UTC by v
Modified: 2017-11-06 10:24 UTC (History)
3 users (show)

See Also:
Kernel Version: 4.8,4.9
Subsystem:
Regression: No
Bisected commit-id:

Attachments
kernel config (178.47 KB, application/x-config)
2016-10-17 04:39 UTC, v 		Details
Add an attachment (proposed patch, testcase, etc.)

Description v 2016-10-17 04:14:08 UTC 
Hello,

I have found a strange bug with IOMMU: when I enable the IOMMU and put the mouse cursor at any width on 885'th or 1019'th pixel from the top, the screen glitches appear, like flickering or tearing. 
It's difficult to explain, please see the videos: 
IOMMU enabled: http://robolab.it/iommu/iommu_on.mp4 (28M)
IOMMU disabled: http://robolab.it/iommu/iommu_off.mp4 (3.7M)

The bug appears with Linux 4.7.6, 4.7.7, 4.8.0 and 4.8.1. 
I have not tried the current releases (4.8.2 and 4.7.8) yet.

System: Clevo P640RE laptop with Intel Core i7-6700HQ CPU
OS: openSuSE 13.2 x86_64
Comment 1 v 2016-10-17 04:39:41 UTC 
Created attachment 241861 [details]
kernel config

Forgot to mention that nothing new appears in dmesg when the screen flickers.
Comment 2 v 2016-10-18 11:39:03 UTC 
Update: booting with "intel_iommu=on,igfx_off" removes screen flickering with mouse cursor on 885th and 1019th pixels height.
Comment 3 kolAflash 2016-10-21 15:54:28 UTC 
Maybe related: https://bugs.freedesktop.org/show_bug.cgi?id=97450
Comment 4 v 2016-11-17 09:29:25 UTC 
I have installed the kernel 4.8.7 because I saw many improvements with i915 in the changelog, but the problem still persists.
Comment 5 v 2017-02-20 08:26:33 UTC 
The problem still persists in kernel version 4.9.11. 

However I've changed the Importance field to "Low" and Status to RESOLVED because I can live with the workaround "intel_iommu=on,igfx_off" and seems that this bug does not affect other people.
Comment 6 Adrian 2017-11-06 10:23:29 UTC 
Hello,
Could you point a parch which fixes this issue ?
Current Ubuntu kernel seems to suffer this bug.
Comment 7 Adrian 2017-11-06 10:24:41 UTC 
I am sorry for last comment. I chose wrong tab in the browser.
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