I bisected this down to the following commit, which suggests we need a
fix for ThunderX IOMMU config, but can consider disabling
ARM_SMMU_DISABLE_BYPASS_BY_DEFAULT until then. To confirm, I verified
that 5.3 boots fine with arm-smmu.disable_bypass=n on the cmdline.
commit 954a03be033c7cef80ddc232e7cbdb17df735663
Author: Douglas Anderson <REDACTED>
Date: Fri Mar 1 11:20:17 2019 -0800
iommu/arm-smmu: Break insecure users by disabling bypass by default
If you're bisecting why your peripherals stopped working, it's
probably this CL. Specifically if you see this in your dmesg:
Unexpected global fault, this could be serious
...then it's almost certainly this CL.
Running your IOMMU-enabled peripherals with the IOMMU in bypass mode
is insecure and effectively disables the protection they provide.
There are few reasons to allow unmatched stream bypass, and even fewer
good ones.
This patch starts the transition over to make it much harder to run
your system insecurely. Expected steps:
1. By default disable bypass (so anyone insecure will notice) but make
it easy for someone to re-enable bypass with just a KConfig change.
That's this patch.
2. After people have had a little time to come to grips with the fact
that they need to set their IOMMUs properly and have had time to
dig into how to do this, the KConfig will be eliminated and bypass
will simply be disabled. Folks who are truly upset and still
haven't fixed their system can either figure out how to add
'arm-smmu.disable_bypass=n' to their command line or revert the
patch in their own private kernel. Of course these folks will be
less secure.
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https://bugs.launchpad.net/bugs/1845820
Title:
arm64: loop on boot after installing linux-generic-hwe-18.04-edge
/bionic-proposed
Status in linux package in Ubuntu:
Confirmed
Status in linux-meta-hwe-edge package in Ubuntu:
Confirmed
Bug description:
Description:
system is stuck in a loop after installing
linux-generic-hwe-18.04-edge/bionic-proposed
System:
Cavium CN88XX
Board Model: crb-1s
SKU: CN8890-2000BG2601-AAP-PR-Y-G
1) Ubuntu 18.04.3 LTS (GNU/Linux 5.0.0-23-generic aarch64)
Description: Ubuntu 18.04.3 LTS
Release: 18.04
2) ((enable -proposed archive))
linux-generic-hwe-18.04-edge:
Installed: 5.0.0.23.79
Candidate: 5.3.0.12.83
Version table:
5.3.0.12.83 500
500 http://ports.ubuntu.com/ubuntu-ports bionic-proposed/main arm64
Packages
*** 5.0.0.23.79 500
500 http://ports.ubuntu.com/ubuntu-ports bionic-updates/main arm64
Packages
100 /var/lib/dpkg/status
5.0.0.20.76 500
500 http://ports.ubuntu.com/ubuntu-ports bionic-security/main arm64
Packages
3)
a. install linux-generic-hwe-18.04-edge/bionic-proposed 5.3.0.12.83 arm64
[upgradable from: 5.0.0.23.79]
b. reboot
c. ssh into the system
4)
a. installed linux-generic-hwe-18.04-edge/bionic-proposed
b. system is stuck in a boot loop
```
linux-generic-hwe-18.04-edge/bionic-proposed 5.3.0.12.83 arm64 [upgradable
from: 5.0.0.23.79]
Complete Generic Linux kernel and headers
```
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