I noticed this in syslog while investigating an unrelated issue today. I have Focal installed on a Fujitsu RX2530 M5 server with two Xeon Gold 6240 18c/36t CPUs installed. Every reboot results in the following MSR stack trace: Dec 3 17:34:31 nabbit kernel: [ 0.358281] smp: Bringing up secondary CPUs ... Dec 3 17:34:31 nabbit kernel: [ 0.358417] x86: Booting SMP configuration: Dec 3 17:34:31 nabbit kernel: [ 0.358419] .... node #0, CPUs: #1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12 #13 #14 #15 #16 #17 Dec 3 17:34:31 nabbit kernel: [ 0.407645] .... node #1, CPUs: #18 Dec 3 17:34:31 nabbit kernel: [ 0.002463] microcode: microcode updated early to revision 0x4003003, date = 2020-06-18 Dec 3 17:34:31 nabbit kernel: [ 0.002463] smpboot: CPU 18 Converting physical 0 to logical die 1 Dec 3 17:34:31 nabbit kernel: [ 0.002463] unchecked MSR access error: WRMSR to 0x10f (tried to write 0x0000000000000000) at rIP: 0xffffffff81c78b04 (native_write_msr+0x4/0x30) Dec 3 17:34:31 nabbit kernel: [ 0.002463] Call Trace: Dec 3 17:34:31 nabbit kernel: [ 0.002463] ? intel_pmu_cpu_starting+0x87/0x270 Dec 3 17:34:31 nabbit kernel: [ 0.002463] ? x86_pmu_dead_cpu+0x30/0x30 Dec 3 17:34:31 nabbit kernel: [ 0.002463] x86_pmu_starting_cpu+0x1a/0x30 Dec 3 17:34:31 nabbit kernel: [ 0.002463] cpuhp_invoke_callback+0x9b/0x580 Dec 3 17:34:31 nabbit kernel: [ 0.002463] notify_cpu_starting+0x66/0x80 Dec 3 17:34:31 nabbit kernel: [ 0.002463] start_secondary+0xaa/0x1c0 Dec 3 17:34:31 nabbit kernel: [ 0.002463] secondary_startup_64+0xa4/0xb0 Dec 3 17:34:31 nabbit kernel: [ 0.498575] #19 #20 #21 #22 #23 #24 #25 #26 #27 #28 #29 #30 #31 #32 #33 #34 #35 Dec 3 17:34:31 nabbit kernel: [ 0.618576] .... node #0, CPUs: #36 Dec 3 17:34:31 nabbit kernel: [ 0.623308] MDS CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/mds.html for more details. Dec 3 17:34:31 nabbit kernel: [ 0.623308] TAA CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/tsx_async_abort.html for more details. Dec 3 17:34:31 nabbit kernel: [ 0.623308] #37 #38 #39 #40 #41 #42 #43 #44 #45 #46 #47 #48 #49 #50 #51 #52 #53 Dec 3 17:34:31 nabbit kernel: [ 0.672450] .... node #1, CPUs: #54 #55 #56 #57 #58 #59 #60 #61 #62 #63 #64 #65 #66 #67 #68 #69 #70 #71 Dec 3 17:34:31 nabbit kernel: [ 0.729432] smp: Brought up 2 nodes, 72 CPUs Dec 3 17:34:31 nabbit kernel: [ 0.729432] smpboot: Max logical packages: 2 Dec 3 17:34:31 nabbit kernel: [ 0.729432] smpboot: Total of 72 processors activated (374479.29 BogoMIPS) Dec 3 17:34:31 nabbit kernel: [ 0.358281] smp: Bringing up secondary CPUs ... Dec 3 17:34:31 nabbit kernel: [ 0.358417] x86: Booting SMP configuration: Dec 3 17:34:31 nabbit kernel: [ 0.358419] .... node #0, CPUs: #1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12 #13 #14 #15 #16 #17 Dec 3 17:34:31 nabbit kernel: [ 0.407645] .... node #1, CPUs: #18 Dec 3 17:34:31 nabbit kernel: [ 0.002463] microcode: microcode updated early to revision 0x4003003, date = 2020-06-18 Dec 3 17:34:31 nabbit kernel: [ 0.002463] smpboot: CPU 18 Converting physical 0 to logical die 1 Dec 3 17:34:31 nabbit kernel: [ 0.002463] unchecked MSR access error: WRMSR to 0x10f (tried to write 0x0000000000000000) at rIP: 0xffffffff81c78b04 (native_write_msr+0x4/0x30) Dec 3 17:34:31 nabbit kernel: [ 0.002463] Call Trace: Dec 3 17:34:31 nabbit kernel: [ 0.002463] ? intel_pmu_cpu_starting+0x87/0x270 Dec 3 17:34:31 nabbit kernel: [ 0.002463] ? x86_pmu_dead_cpu+0x30/0x30 Dec 3 17:34:31 nabbit kernel: [ 0.002463] x86_pmu_starting_cpu+0x1a/0x30 Dec 3 17:34:31 nabbit kernel: [ 0.002463] cpuhp_invoke_callback+0x9b/0x580 Dec 3 17:34:31 nabbit kernel: [ 0.002463] notify_cpu_starting+0x66/0x80 Dec 3 17:34:31 nabbit kernel: [ 0.002463] start_secondary+0xaa/0x1c0 Dec 3 17:34:31 nabbit kernel: [ 0.002463] secondary_startup_64+0xa4/0xb0 Dec 3 17:34:31 nabbit kernel: [ 0.498575] #19 #20 #21 #22 #23 #24 #25 #26 #27 #28 #29 #30 #31 #32 #33 #34 #35 Dec 3 17:34:31 nabbit kernel: [ 0.618576] .... node #0, CPUs: #36 Dec 3 17:34:31 nabbit kernel: [ 0.623308] MDS CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/mds.html for more details. Dec 3 17:34:31 nabbit kernel: [ 0.623308] TAA CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/tsx_async_abort.html for more details. Dec 3 17:34:31 nabbit kernel: [ 0.623308] #37 #38 #39 #40 #41 #42 #43 #44 #45 #46 #47 #48 #49 #50 #51 #52 #53 Dec 3 17:34:31 nabbit kernel: [ 0.672450] .... node #1, CPUs: #54 #55 #56 #57 #58 #59 #60 #61 #62 #63 #64 #65 #66 #67 #68 #69 #70 #71 Dec 3 17:34:31 nabbit kernel: [ 0.729432] smp: Brought up 2 nodes, 72 CPUs Dec 3 17:34:31 nabbit kernel: [ 0.729432] smpboot: Max logical packages: 2 Dec 3 17:34:31 nabbit kernel: [ 0.729432] smpboot: Total of 72 processors activated (374479.29 BogoMIPS) it doesn't seem to be catastrophic, but is troubling to find this in the logs. On a different FJ server (RX2540 M5) with 2x Xeon Gold 6242 cpus (16c/32T) This trace is not present, so this could indicate something with this particular machine, or this particular CPU model. Here is the smp boot from the non-failing machine: ec 2 16:02:56 polari kernel: [ 1.519306] Freeing SMP alternatives memory: 40K Dec 2 16:02:56 polari kernel: [ 1.522346] smpboot: CPU0: Intel(R) Xeon(R) Gold 6242 CPU @ 2.80GHz (family: 0x6, model: 0x55, stepping: 0x5) Dec 2 16:02:56 polari kernel: [ 1.522575] Performance Events: PEBS fmt3+, Skylake events, 32-deep LBR, full-width counters, Intel PMU driver. Dec 2 16:02:56 polari kernel: [ 1.522584] ... version: 4 Dec 2 16:02:56 polari kernel: [ 1.522585] ... bit width: 48 Dec 2 16:02:56 polari kernel: [ 1.522587] ... generic registers: 4 Dec 2 16:02:56 polari kernel: [ 1.522588] ... value mask: 0000ffffffffffff Dec 2 16:02:56 polari kernel: [ 1.522589] ... max period: 00007fffffffffff Dec 2 16:02:56 polari kernel: [ 1.522591] ... fixed-purpose events: 3 Dec 2 16:02:56 polari kernel: [ 1.522592] ... event mask: 000000070000000f Dec 2 16:02:56 polari kernel: [ 1.522665] rcu: Hierarchical SRCU implementation. Dec 2 16:02:56 polari kernel: [ 1.524965] NMI watchdog: Enabled. Permanently consumes one hw-PMU counter. Dec 2 16:02:56 polari kernel: [ 1.525875] smp: Bringing up secondary CPUs ... Dec 2 16:02:56 polari kernel: [ 1.525990] x86: Booting SMP configuration: Dec 2 16:02:56 polari kernel: [ 1.525992] .... node #0, CPUs: #1 #2 #3 Dec 2 16:02:56 polari kernel: [ 1.533485] .... node #1, CPUs: #4 #5 #6 #7 Dec 2 16:02:56 polari kernel: [ 1.543960] .... node #0, CPUs: #8 #9 #10 #11 Dec 2 16:02:56 polari kernel: [ 1.553544] .... node #1, CPUs: #12 #13 #14 #15 Dec 2 16:02:56 polari kernel: [ 1.564701] .... node #2, CPUs: #16 Dec 2 16:02:56 polari kernel: [ 0.002176] smpboot: CPU 16 Converting physical 0 to logical die 1 Dec 2 16:02:56 polari kernel: [ 1.651254] #17 #18 #19 Dec 2 16:02:56 polari kernel: [ 1.659278] .... node #3, CPUs: #20 #21 #22 #23 Dec 2 16:02:56 polari kernel: [ 1.669669] .... node #2, CPUs: #24 #25 #26 #27 Dec 2 16:02:56 polari kernel: [ 1.680637] .... node #3, CPUs: #28 #29 #30 #31 Dec 2 16:02:56 polari kernel: [ 1.691394] .... node #0, CPUs: #32 Dec 2 16:02:56 polari kernel: [ 1.693845] MDS CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/mds.html for more details. Dec 2 16:02:56 polari kernel: [ 1.693845] TAA CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/tsx_async_abort.html for more details. Dec 2 16:02:56 polari kernel: [ 1.693845] #33 #34 #35 Dec 2 16:02:56 polari kernel: [ 1.701504] .... node #1, CPUs: #36 #37 #38 #39 Dec 2 16:02:56 polari kernel: [ 1.712687] .... node #0, CPUs: #40 #41 #42 #43 Dec 2 16:02:56 polari kernel: [ 1.723263] .... node #1, CPUs: #44 #45 #46 #47 Dec 2 16:02:56 polari kernel: [ 1.733658] .... node #2, CPUs: #48 #49 #50 #51 Dec 2 16:02:56 polari kernel: [ 1.744372] .... node #3, CPUs: #52 #53 #54 #55 Dec 2 16:02:56 polari kernel: [ 1.755243] .... node #2, CPUs: #56 #57 #58 #59 Dec 2 16:02:56 polari kernel: [ 1.765640] .... node #3, CPUs: #60 #61 #62 #63 Dec 2 16:02:56 polari kernel: [ 1.776965] smp: Brought up 4 nodes, 64 CPUs Dec 2 16:02:56 polari kernel: [ 1.776965] smpboot: Max logical packages: 2 Dec 2 16:02:56 polari kernel: [ 1.776965] smpboot: Total of 64 processors activated (358464.56 BogoMIPS) ec 2 16:02:56 polari kernel: [ 1.519306] Freeing SMP alternatives memory: 40K Dec 2 16:02:56 polari kernel: [ 1.522346] smpboot: CPU0: Intel(R) Xeon(R) Gold 6242 CPU @ 2.80GHz (family: 0x6, model: 0x55, stepping: 0x5) Dec 2 16:02:56 polari kernel: [ 1.522575] Performance Events: PEBS fmt3+, Skylake events, 32-deep LBR, full-width counters, Intel PMU driver. Dec 2 16:02:56 polari kernel: [ 1.522584] ... version: 4 Dec 2 16:02:56 polari kernel: [ 1.522585] ... bit width: 48 Dec 2 16:02:56 polari kernel: [ 1.522587] ... generic registers: 4 Dec 2 16:02:56 polari kernel: [ 1.522588] ... value mask: 0000ffffffffffff Dec 2 16:02:56 polari kernel: [ 1.522589] ... max period: 00007fffffffffff Dec 2 16:02:56 polari kernel: [ 1.522591] ... fixed-purpose events: 3 Dec 2 16:02:56 polari kernel: [ 1.522592] ... event mask: 000000070000000f Dec 2 16:02:56 polari kernel: [ 1.522665] rcu: Hierarchical SRCU implementation. Dec 2 16:02:56 polari kernel: [ 1.524965] NMI watchdog: Enabled. Permanently consumes one hw-PMU counter. Dec 2 16:02:56 polari kernel: [ 1.525875] smp: Bringing up secondary CPUs ... Dec 2 16:02:56 polari kernel: [ 1.525990] x86: Booting SMP configuration: Dec 2 16:02:56 polari kernel: [ 1.525992] .... node #0, CPUs: #1 #2 #3 Dec 2 16:02:56 polari kernel: [ 1.533485] .... node #1, CPUs: #4 #5 #6 #7 Dec 2 16:02:56 polari kernel: [ 1.543960] .... node #0, CPUs: #8 #9 #10 #11 Dec 2 16:02:56 polari kernel: [ 1.553544] .... node #1, CPUs: #12 #13 #14 #15 Dec 2 16:02:56 polari kernel: [ 1.564701] .... node #2, CPUs: #16 Dec 2 16:02:56 polari kernel: [ 0.002176] smpboot: CPU 16 Converting physical 0 to logical die 1 Dec 2 16:02:56 polari kernel: [ 1.651254] #17 #18 #19 Dec 2 16:02:56 polari kernel: [ 1.659278] .... node #3, CPUs: #20 #21 #22 #23 Dec 2 16:02:56 polari kernel: [ 1.669669] .... node #2, CPUs: #24 #25 #26 #27 Dec 2 16:02:56 polari kernel: [ 1.680637] .... node #3, CPUs: #28 #29 #30 #31 Dec 2 16:02:56 polari kernel: [ 1.691394] .... node #0, CPUs: #32 Dec 2 16:02:56 polari kernel: [ 1.693845] MDS CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/mds.html for more details. Dec 2 16:02:56 polari kernel: [ 1.693845] TAA CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/tsx_async_abort.html for more details. Dec 2 16:02:56 polari kernel: [ 1.693845] #33 #34 #35 Dec 2 16:02:56 polari kernel: [ 1.701504] .... node #1, CPUs: #36 #37 #38 #39 Dec 2 16:02:56 polari kernel: [ 1.712687] .... node #0, CPUs: #40 #41 #42 #43 Dec 2 16:02:56 polari kernel: [ 1.723263] .... node #1, CPUs: #44 #45 #46 #47 Dec 2 16:02:56 polari kernel: [ 1.733658] .... node #2, CPUs: #48 #49 #50 #51 Dec 2 16:02:56 polari kernel: [ 1.744372] .... node #3, CPUs: #52 #53 #54 #55 Dec 2 16:02:56 polari kernel: [ 1.755243] .... node #2, CPUs: #56 #57 #58 #59 Dec 2 16:02:56 polari kernel: [ 1.765640] .... node #3, CPUs: #60 #61 #62 #63 Dec 2 16:02:56 polari kernel: [ 1.776965] smp: Brought up 4 nodes, 64 CPUs Dec 2 16:02:56 polari kernel: [ 1.776965] smpboot: Max logical packages: 2 Dec 2 16:02:56 polari kernel: [ 1.776965] smpboot: Total of 64 processors activated (358464.56 BogoMIPS) ProblemType: Bug DistroRelease: Ubuntu 20.04 Package: linux-image-5.4.0-56-generic 5.4.0-56.62 ProcVersionSignature: Ubuntu 5.4.0-56.62-generic 5.4.73 Uname: Linux 5.4.0-56-generic x86_64 NonfreeKernelModules: nvidia_modeset nvidia AlsaDevices: total 0 crw-rw---- 1 root audio 116, 1 Dec 3 20:02 seq crw-rw---- 1 root audio 116, 33 Dec 3 20:02 timer AplayDevices: Error: [Errno 2] No such file or directory: 'aplay' ApportVersion: 2.20.11-0ubuntu27.10 Architecture: amd64 ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord' AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1: CasperMD5CheckResult: skip Date: Thu Dec 3 20:15:56 2020 IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig' Lsusb: Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 001 Device 002: ID 0424:2533 Microchip Technology, Inc. (formerly SMSC) Bus 001 Device 004: ID 046b:ff10 American Megatrends, Inc. Virtual Keyboard and Mouse Bus 001 Device 003: ID 046b:ff01 American Megatrends, Inc. Virtual Hub Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub MachineType: FUJITSU PRIMERGY RX2530 M5 PciMultimedia: ProcEnviron: TERM=screen-256color PATH=(custom, no user) LANG=C.UTF-8 SHELL=/bin/bash ProcFB: 0 mgag200drmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.4.0-56-generic root=UUID=0e82de6f-eac2-426d-b89e-e52b1acaa792 ro console=tty0 RelatedPackageVersions: linux-restricted-modules-5.4.0-56-generic N/A linux-backports-modules-5.4.0-56-generic N/A linux-firmware 1.187.4 RfKill: Error: [Errno 2] No such file or directory: 'rfkill' SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 10/17/2019 dmi.bios.vendor: FUJITSU // American Megatrends Inc. dmi.bios.version: V5.0.0.14 R1.15.0 for D3383-B1x dmi.board.name: D3383-B1 dmi.board.vendor: FUJITSU dmi.board.version: S26361-D3383-B13 WGS04 GS01 dmi.chassis.asset.tag: nabbit dmi.chassis.type: 23 dmi.chassis.vendor: FUJITSU dmi.chassis.version: RX2530M5R3 dmi.modalias: dmi:bvnFUJITSU//AmericanMegatrendsInc.:bvrV5.0.0.14R1.15.0forD3383-B1x:bd10/17/2019:svnFUJITSU:pnPRIMERGYRX2530M5:pvr:rvnFUJITSU:rnD3383-B1:rvrS26361-D3383-B13WGS04GS01:cvnFUJITSU:ct23:cvrRX2530M5R3: dmi.product.family: SERVER dmi.product.name: PRIMERGY RX2530 M5 dmi.product.sku: S26361-K1659-Vxxx dmi.sys.vendor: FUJITSU