On Wednesday, 17 July 2019 04:21:07 BST Corbin wrote: > On 7/14/19 8:26 AM, Mick wrote: > > Then I came across this old message regarding Piledriver CPUs: > > https://lists.debian.org/debian-security/2016/03/msg00084.html The > > post refers to model 2 of cpu family 21. Not all models in the same > > family, only model 2. So I am thinking although patch files are named > > per CPU family, whether they are applicable and applied as an update > > to the CPU is probably determined by the particular CPU *model*. > > Logically, errata in previous CPU revisions may have been fixed in > > later models of the same family and therefore such microcode updates > > would not be needed. When offered by the OS the CPU won't select to > > have them applied. This explains why my AMD models, which are later > > revisions of the same 15h family do not apply any microcode updates - > > they don't need them. Please share if you know differently and thank > > you all for your responses. > > Remember a while back when I mentioned that "lwp" had disappeared from > my /proc/cpuinfo? > > They restored "lwp" with this commit : > > https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.gi > > t/commit/?id=7518922bd5b98b137af7aaf3c836f5a498e91609 > So it stands to reason that the microcode only applies specific patches > to specific problems per CPU. > > Reference : > > Darkstar ~ # cat /proc/cpuinfo > > processor : 0 > > vendor_id : AuthenticAMD > > cpu family : 21 > > model : 2 > > model name : AMD FX(tm)-9590 Eight-Core Processor > > stepping : 0 > > microcode : 0x6000852 > > cpu MHz : 4685.390 > > cache size : 2048 KB > > Output of /sys/devices/system/cpu/vulnerabilities : > > Darkstar ~ # cat /sys/devices/system/cpu/vulnerabilities/l1tf > > Not affected > > Darkstar ~ # cat /sys/devices/system/cpu/vulnerabilities/mds > > Not affected > > Darkstar ~ # cat /sys/devices/system/cpu/vulnerabilities/meltdown > > Not affected > > Darkstar ~ # cat > > /sys/devices/system/cpu/vulnerabilities/spec_store_bypass > > Mitigation: Speculative Store Bypass disabled > > Darkstar ~ # cat /sys/devices/system/cpu/vulnerabilities/spectre_v1 > > Mitigation: __user pointer sanitization > > Darkstar ~ # cat /sys/devices/system/cpu/vulnerabilities/spectre_v2 > > Mitigation: Full AMD retpoline, IBPB: always-on, STIBP: disabled, RSB > > filling > > Corbin
Hmm ... My last line looks the same like Rich's, but different to yours: # cat /sys/devices/system/cpu/vulnerabilities/spectre_v2 Mitigation: Full AMD retpoline, STIBP: disabled, RSB filling I don't have IBPB mentioned in there at all. I'm on gentoo-sources-4.19.57. Are you running a later kernel? According to this article a microcode update seems to be necessary, but I'm not sure if this statement only applies to Intel CPUs: https://access.redhat.com/articles/3311301#indirect-branch-prediction-barriers-ibpb-10 -- Regards, Mick
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