disable Intel DMA remapping by default

[Andrea Righi]

[Impact]

It seems that enabling Intel IOMMU can cause some weird gfx problems, see for example:

 https://bugs.launchpad.net/bugs/1971146
 https://bugs.launchpad.net/bugs/1965882

[Test case]

We don't have any specific test case, only other bug reports that tracked down the origin of the issue as being introduced when CONFIG_INTEL_IOMMU_DEFAULT_ON has been enabled by default.

[Fix]

Revert "UBUNTU: [Config] enable Intel DMA remapping options by default"

[Regression potential]

DMA remapping device not present at boot by default, users that require this feature will need to specifically add intel_iommu=on to the kernel boot parameters to enable it.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1971699

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Matthew Ruffell (mruffell)]

A user has ran into a storage performance issue, and it has been traced back to CONFIG_INTEL_IOMMU_DEFAULT_ON being enabled.

They have a Dell XtremIO FC storage server, running VMWare ESXi 7.0U3, with 4x pvscsi controllers (2 LUNs per controller), running a single large LV with 8-way 1MB stripe.

There are Ubuntu 20.04 and 22.04 VMs running on the same server. The VMs are attached to the storage unit through iSCSI.

When running the following FIO script:

[write1]
filename=/dev/xio2data/prd01
readwrite=randwrite
random_generator=tausworthe64
blocksize=8K
ioengine=libaio
iodepth=32
direct=1
runtime=30
numjobs=8
group_reporting
invalidate=0

On 20.04 with 5.4.0-109-generic they see:

WRITE: bw=1010MiB/s (1059MB/s), 1010MiB/s-1010MiB/s (1059MB/s-1059MB/s), io=29.6GiB (31.8GB), run=30007-30007msec

They note a 2%-3% %SYS load.

On 22.04 with 5.15.0-27-generic they see:

WRITE: bw=568MiB/s (595MB/s), 568MiB/s-568MiB/s (595MB/s-595MB/s), io=16.6GiB (17.9GB), run=30007-30007msec

They note a consistent 18%-19% %SYS load, and poor performance.

It seems VMWare emulates a IOMMU, and their VMs were configuring 8 IOMMU groups for their PCI devices, and it was significantly impacting iSCSI performance.

When intel_iommu=off was supplied on the kernel command line, the performance issue is no longer present. This is a suitable workaround for the time being.

This user is in agreement with and asking for CONFIG_INTEL_IOMMU_DEFAULT_ON to be disabled.

[Matthew Ruffell (mruffell)]

A user has reported extensive performance issues with a Lenovo Thinkpad X1 Extreme Gen 2 laptop computer, in bug 1973434. The user reports video playback hangs, browser hangs and virtual machines hanging.

Their dmesg indicates the system has 2x IOMMUs and there are 25 groups being configured. They tested "intel_iommu=off", and the performance issues are no longer seen.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux/5.15.0-36.37 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-jammy' to 'verification-done-jammy'. If the problem still exists, change the tag 'verification-needed-jammy' to 'verification-failed-jammy'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 5.15.0-40.43

---------------
linux (5.15.0-40.43) jammy; urgency=medium

  * jammy/linux: 5.15.0-40.43 -proposed tracker (LP: #1978610)

  * Packaging resync (LP: #1786013)
    - debian/dkms-versions -- update from kernel-versions (main/2022.05.30)

  * [SRU][OEM-5.14/OEM-5.17/J][PATCH 0/2] Fix system hangs after s2idle on AMD
    A+A GPU (LP: #1975804)
    - Revert "drm/amd/pm: keep the BACO feature enabled for suspend"
    - drm/amd: Don't reset dGPUs if the system is going to s2idle

  * [SRU][OEM-5.14/OEM-5.17/J][PATCH 0/1] Read the discovery registers for
    AMD_SFH (LP: #1975798)
    - HID: amd_sfh: Add support for sensor discovery

  * [UBUNTU 20.04] CPU-MF: add extended counter set definitions for new IBM z16
    (LP: #1974433)
    - s390/cpumf: add new extended counter set for IBM z16

  * [UBUNTU 20.04] KVM nesting support leaks too much memory, might result in
    stalls during cleanup (LP: #1974017)
    - KVM: s390: vsie/gmap: reduce gmap_rmap overhead

  * [UBUNTU 20.04] Null Pointer issue in nfs code running Ubuntu on IBM Z
    (LP: #1968096)
    - NFS: Fix up nfs_ctx_key_to_expire()

  * Fix REG_WAIT timeout for Yellow Carp (LP: #1971417)
    - drm/amd/display: Clear encoder assignments when state cleared.
    - drm/amd/display: fix stale info in link encoder assignment
    - drm/amd/display: Query all entries in assignment table during updates.
    - drm/amd/display: Initialise encoder assignment when initialising dc_state

  * Enable hotspot feature for Realtek 8821CE (LP: #1969326)
    - rtw88: Add update beacon flow for AP mode
    - rtw88: 8821c: Enable TX report for management frames
    - rtw88: do PHY calibration while starting AP
    - rtw88: 8821c: fix debugfs rssi value
    - rtw88: add ieee80211:sta_rc_update ops

  * prevent kernel panic with overlayfs + shiftfs (LP: #1973620)
    - SAUCE: overlayfs: prevent dereferencing struct file in ovl_vm_prfile_set()

  * disable Intel DMA remapping by default (LP: #1971699)
    - Revert "UBUNTU: [Config] enable Intel DMA remapping options by default"

  * Mute/mic LEDs no function on Elitebook 630 (LP: #1974111)
    - ALSA: hda/realtek: fix right sounds and mute/micmute LEDs for HP machine

  * [Regression] Real-time Kernel Build Failure (LP: #1972899)
    - x86/mm: Include spinlock_t definition in pgtable.

  * build backport-iwlwifi-dkms as linux-modules-iwlwifi-ABI (LP: #1969434)
    - [Packaging] support standalone dkms module builds
    - [Packaging] drop do_<mod> arch specific configs

  * IPU6 camera has no function on Andrews MLK (LP: #1964983)
    - SAUCE: IPU6: 2022-03-11 alpha release for Andrews MLK
    - [Config] IPU6: enable OV02C10 sensor
    - SAUCE: IPU6: 2022-04-01 Andrews MLK PV release
    - SAUCE: spi: ljca: return when a sub-transaction first failed
    - SACUE: ljca: disable parallelly stub write
    - SAUCE: ljca: fix race condition issue in runtime PM
    - SAUCE: i2c-ljca: fix a null pointer access issue on tgl
    - SAUCE: ljca: fix a typo issue
    - SAUCE: ljca: assume stub enum failed as a warning
    - SAUCE: mei: cleanup header file including
    - SAUCE: intel_ulpss: Replaced by LJCA and remove
    ...

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-hwe-5.15/5.15.0-41.44~20.04.1 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-focal' to 'verification-done-focal'. If the problem still exists, change the tag 'verification-needed-focal' to 'verification-failed-focal'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Richard Hughes (richard-hughes)]

> * disable Intel DMA remapping by default (LP: #1971699)

Doesn't this add a massive security issue, in that you can plug a malicious thunderbolt peripheral into any Ubuntu laptop and read the entire unencrypted RAM space? The IOMMU is there for a reason...

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 5.19.0-15.15

---------------
linux (5.19.0-15.15) kinetic; urgency=medium

  * kinetic/linux: 5.19.0-15.15 -proposed tracker (LP: #1983335)

  * Miscellaneous Ubuntu changes
    - [Config] update annotations to support both gcc-11 and gcc-12

 -- Andrea Righi <email address hidden> Tue, 02 Aug 2022 09:23:01 +0200

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux/5.15.0-102.112 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-jammy-linux' to 'verification-done-jammy-linux'. If the problem still exists, change the tag 'verification-needed-jammy-linux' to 'verification-failed-jammy-linux'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-aws-fips/5.15.0-1057.63+fips1 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-jammy-linux-aws-fips' to 'verification-done-jammy-linux-aws-fips'. If the problem still exists, change the tag 'verification-needed-jammy-linux-aws-fips' to 'verification-failed-jammy-linux-aws-fips'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-aws-5.15/5.15.0-1057.63~20.04.1 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-focal-linux-aws-5.15' to 'verification-done-focal-linux-aws-5.15'. If the problem still exists, change the tag 'verification-needed-focal-linux-aws-5.15' to 'verification-failed-focal-linux-aws-5.15'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-nvidia-tegra/5.15.0-1023.23 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-jammy-linux-nvidia-tegra' to 'verification-done-jammy-linux-nvidia-tegra'. If the problem still exists, change the tag 'verification-needed-jammy-linux-nvidia-tegra' to 'verification-failed-jammy-linux-nvidia-tegra'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-nvidia-tegra-5.15/5.15.0-1023.23~20.04.1 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-focal-linux-nvidia-tegra-5.15' to 'verification-done-focal-linux-nvidia-tegra-5.15'. If the problem still exists, change the tag 'verification-needed-focal-linux-nvidia-tegra-5.15' to 'verification-failed-focal-linux-nvidia-tegra-5.15'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Roxana Nicolescu (roxanan)]

With no test case, I'll mark this as verified

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-intel-iotg/5.15.0-1052.58 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-jammy-linux-intel-iotg' to 'verification-done-jammy-linux-intel-iotg'. If the problem still exists, change the tag 'verification-needed-jammy-linux-intel-iotg' to 'verification-failed-jammy-linux-intel-iotg'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-bluefield/5.15.0-1040.42 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-jammy-linux-bluefield' to 'verification-done-jammy-linux-bluefield'. If the problem still exists, change the tag 'verification-needed-jammy-linux-bluefield' to 'verification-failed-jammy-linux-bluefield'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-oracle-5.15/5.15.0-1055.61~20.04.1 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-focal-linux-oracle-5.15' to 'verification-done-focal-linux-oracle-5.15'. If the problem still exists, change the tag 'verification-needed-focal-linux-oracle-5.15' to 'verification-failed-focal-linux-oracle-5.15'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-nvidia-tegra-igx/5.15.0-1010.10 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-jammy-linux-nvidia-tegra-igx' to 'verification-done-jammy-linux-nvidia-tegra-igx'. If the problem still exists, change the tag 'verification-needed-jammy-linux-nvidia-tegra-igx' to 'verification-failed-jammy-linux-nvidia-tegra-igx'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-xilinx-zynqmp/5.15.0-1029.33 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-jammy-linux-xilinx-zynqmp' to 'verification-done-jammy-linux-xilinx-zynqmp'. If the problem still exists, change the tag 'verification-needed-jammy-linux-xilinx-zynqmp' to 'verification-failed-jammy-linux-xilinx-zynqmp'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!