** Changed in: linux (Ubuntu Trusty)
Status: In Progress => Fix Committed
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https://bugs.launchpad.net/bugs/1774082
Title:
Trusty cannot load microcode for family 17h AMD processors
Status in linux package in Ubuntu:
Invalid
Status in linux source package in Trusty:
Fix Committed
Bug description:
[Impact]
AMD has recently updated the microcode in the linux-firmware tree for
family 17h processors to address Spectre variant 2. The Trusty 3.13
kernel cannot load the microcode because it is missing a backport of
upstream patch f4e9b7af0cd58dd039a0fb2cd67d57cea4889abf which leaves
AMD machines vulnerable.
[Test Case (option 1)]
Test must be done on a 17h family processor:
1) Take note of the microcode version before applying updated
microcode:
$ sudo cat /sys/devices/system/cpu/cpu0/microcode/version
0x8001227
2) Get updated amd64-microcode package from the Ubuntu Security Team.
Install it and reboot machine.
3) Verify that the microcode version has changed.
[Test Case (option 2)]
Alternate test case (useful in the situation that the test system is
already running the latest microcode revision due to a BIOS update):
1) Fetch the latest 17h family microcode revision from here (you may
want to verify the signature):
https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-
firmware.git/tree/amd-ucode/microcode_amd_fam17h.bin
2) Move it into /lib/firmware/amd-ucode/
3) Force a microcode reload:
$ echo 1 | sudo tee /sys/devices/system/cpu/microcode/reload
4) Verify that the following error message is *not* in your syslog:
May 30 04:22:55 lodygin kernel: [ 388.290105] microcode: patch size mismatch
May 30 04:22:55 lodygin kernel: [ 388.290149] microcode: Patch-ID
0x08001227: size mismatch.
[Regression Potential]
The regression potential to the kernel revolves around the fact that
the IBRS/IBPB implementation in the 3.13 kernel may not have been put
through its paces yet due to a lack of available microcode updates.
There could be a latent bug present that is uncovered.
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