[Bug 177791] New: screen flickering with intel_iommu=on

[Bug 177791] New: screen flickering with intel_iommu=on

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=177791

            Bug ID: 177791
           Summary: screen flickering with intel_iommu=on
           Product: Virtualization
           Version: unspecified
    Kernel Version: 4.8
          Hardware: Intel
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: kvm
          Assignee: virtualization_kvm@kernel-bugs.osdl.org
          Reporter: v@robolab.it
        Regression: No

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

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[Bug 177791] screen flickering with intel_iommu=on

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=177791

--- Comment #1 from v@robolab.it ---
Created attachment 241861
  --> https://bugzilla.kernel.org/attachment.cgi?id=241861&action=edit
kernel config

Forgot to mention that nothing new appears in dmesg when the screen flickers.

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[Bug 177791] screen flickering with intel_iommu=on

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=177791

--- Comment #2 from v@robolab.it ---
Update: booting with "intel_iommu=on,igfx_off" removes screen flickering with
mouse cursor on 885th and 1019th pixels height.

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[Bug 177791] screen flickering with intel_iommu=on

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=177791

kolAflash <kolAflash@kolahilft.de> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |kolAflash@kolahilft.de

--- Comment #3 from kolAflash <kolAflash@kolahilft.de> ---
Maybe related: https://bugs.freedesktop.org/show_bug.cgi?id=97450

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[Bug 177791] screen flickering with intel_iommu=on

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=177791

--- Comment #4 from v@robolab.it ---
I have installed the kernel 4.8.7 because I saw many improvements with i915 in
the changelog, but the problem still persists.

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[Bug 177791] screen flickering with intel_iommu=on

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=177791

v@robolab.it changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Kernel Version|4.8                         |4.8,4.9
           Severity|normal                      |low

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[Bug 177791] screen flickering with intel_iommu=on

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=177791

v@robolab.it changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |INSUFFICIENT_DATA

--- Comment #5 from v@robolab.it ---
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.

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[Bug 177791] screen flickering with intel_iommu=on

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=177791

Adrian (A.Fiergolski+kernelBugzilla@gmail.com) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |A.Fiergolski+kernelBugzilla
                   |                            |@gmail.com

--- Comment #6 from Adrian (A.Fiergolski+kernelBugzilla@gmail.com) ---
Hello,
Could you point a parch which fixes this issue ?
Current Ubuntu kernel seems to suffer this bug.

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[Bug 177791] screen flickering with intel_iommu=on

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https://bugzilla.kernel.org/show_bug.cgi?id=177791

--- Comment #7 from Adrian (A.Fiergolski+kernelBugzilla@gmail.com) ---
I am sorry for last comment. I chose wrong tab in the browser.

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