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DescriptionEugene Syromiatnikov
2020-05-07 17:14:51 UTC
Currently, due to [1], all microcode updates past revision 0x2000064 are disabled on SKX (1st generation Xeon Skalable Platform, Skylake Scalable Platform, SKL-SP, SKL-X, SKL-W, SKL-D; FF-MM-SS 06-55-04, CPUID 0x50654) by default. This, in fact, too broad blacklist, as the issue affects only Workstation (SKL-W, SKX-W) and HEDT (SKL-X, SKX-X, Basin Falls) segments. As it was suggested quite some time ago, these can be differentiated by referring to bits 5..3 of CAPID0 field of PCU registers device (Bus 1, Device 30, Function 3, VID:DID 8086:2083)[2] (there's some information regarding the device's fields available for BDX[3], but not for SKX[4], and they are indeed different). By implementing a more precise filter, it is possible to avoid issues with the latest CPU errata/CVEs not being mitigated by default in a more common SKL-SP server segment CPU case.
Steps to Reproduce:
1. Install microcode_ctl package, version 20191115-2.el8 or higher on a system with SKL-SP Server segment CPU (Intel Xeon 81xx).
2. Check the dmesg/syslog for disclaimers
3. Check the microcode version populated in /lib/firmware/KERNEL_VERSION/inte-ucode and the early initramfs
Actual results:
Disclaimer is present, older (0x2000064) microcode revision is used.
Expected results:
No disclaimer present, newer (0x2000065) microcode revision is used.
[1] https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files/issues/21
[2] https://www.intel.com/content/dam/www/public/us/en/documents/specification-updates/xeon-scalable-spec-update.pdf#page
[3] xeon-e5-v4-datasheet-vol-2.pdf, page 82
[4] xeon-scalable-mem-ds-vol2-336062-r003.pdf, page 57
microcode revision 0x2006906 for 06-55-04 fixed the hanging problem so the changes for this bug were undone and microcode updates happen by default again on this CPU model. Moving to Verified.
[root@hpe-xl170gen10-01 ~]# rpm -q microcode_ctl
microcode_ctl-20200609-2.el8.x86_64
[root@hpe-xl170gen10-01 ~]# lscpu | grep -i -e family -e model -e stepping
CPU family: 6
Model: 85
Model name: Intel(R) Xeon(R) Gold 6152 CPU @ 2.10GHz
Stepping: 4
[root@hpe-xl170gen10-01 ~]# journalctl --dmesg --no-hostname --output short-monotonic --grep=microcode | cat
-- Logs begin at Wed 2020-07-01 15:56:03 EDT, end at Wed 2020-07-01 19:56:21 EDT. --
[ 0.000000] kernel: microcode: microcode updated early to revision 0x2006906, date = 2020-04-24
[ 7.618030] kernel: microcode: sig=0x50654, pf=0x80, revision=0x2006906
[ 7.629203] kernel: microcode: Microcode Update Driver: v2.2.
[root@hpe-xl170gen10-01 ~]# ls /etc/microcode_ctl/ucode_with_caveats/force*
ls: cannot access '/etc/microcode_ctl/ucode_with_caveats/force*': No such file or directory
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory (microcode_ctl bug fix and enhancement update), and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHEA-2020:4489