Date: Wed, 4 Jul 2018 15:17:25 +0300 From: Vasily Averin <vvs@...tuozzo.com> To: Solar Designer <solar@...nwall.com> Cc: owl-dev@...ts.openwall.com Subject: Re: 32-bit syscall breakage in -431 kernel with KAISER I've reported about microcode_ctl to Red Hat https://bugzilla.redhat.com/show_bug.cgi?id=1598118 On 07/03/2018 09:16 PM, Solar Designer wrote: > On Tue, Jul 03, 2018 at 08:32:57PM +0300, Vasily Averin wrote: >> However then node was crashed on start of microcode_ctl service on host. >> >> I've found that on our kernel __cpuinit moves get_scattered_cpuid_extra() into init section, >> but this function can be called lagally called after initialization, >> from microcode_write() -> spec_ctrl_rescan_cpuid() >> >> Issue was caused by CONFIG_HOTPLUG_CPU enabled on Red Hat but disabled on our kernels. >> Therefore I afraid your kernel should be affected too. >> >> Could you please clarify this question? > > It's quite possible we never tested microcode_ctl on Owl. It isn't part > of Owl, even though there was intent to add it at some point. > > I enabled CONFIG_MICROCODE=m in our kernels in late 2016: > > * Sat Dec 10 2016 Solar Designer <solar-at-owl.openwall.com> 2.6.18-408.el5.028stab120.1.owl5 > - Merged in Red Hat's CVE-2016-5195 "Dirty COW" fix from -416 (slightly > different from the fix included in OpenVZ's 120.3 released earlier) while also > keeping the mitigation introduced in owl4. > - In the x86_64 config, enabled CONFIG_MICROCODE=m, CONFIG_NUMA=y and many > related options, CONFIG_HUGETLB_PAGE=y, CONFIG_HUGETLBFS=y, CONFIG_I2C=m and > many sensors (similar to RHEL's), bumped up CONFIG_NR_CPUS from 32 to 255. > Tested many of these on a Dell PowerEdge R720xd with 2x E5-2660 v2 (NUMA, huge > pages, some I2C sensors, 40 logical CPUs). > > IIRC, I intended to test it on that Dell machine mentioned in there, but > it was already at Intel's latest microcode revision for its CPUs, so I > did not. I think I did test loading of the kernel module, though. > > Alexander >
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