lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Wed, 9 Nov 2022 09:48:33 -0600 From: Eric DeVolder <eric.devolder@...cle.com> To: Borislav Petkov <bp@...en8.de> Cc: linux-kernel@...r.kernel.org, x86@...nel.org, kexec@...ts.infradead.org, ebiederm@...ssion.com, dyoung@...hat.com, bhe@...hat.com, vgoyal@...hat.com, tglx@...utronix.de, mingo@...hat.com, dave.hansen@...ux.intel.com, hpa@...or.com, nramas@...ux.microsoft.com, thomas.lendacky@....com, robh@...nel.org, efault@....de, rppt@...nel.org, david@...hat.com, sourabhjain@...ux.ibm.com, konrad.wilk@...cle.com, boris.ostrovsky@...cle.com Subject: Re: [PATCH v13 7/7] x86/crash: add x86 crash hotplug support On 11/2/22 04:26, Borislav Petkov wrote: > On Tue, Nov 01, 2022 at 10:45:00AM -0500, Eric DeVolder wrote: >> As I'm re-reading that message, I suspect now the preference is to just to >> strike this ifdiffery line in this file and have the code always present? >> >> If the preference is actually for CRASH_HOTPLUG, then let me know. > > Well, it is this part: > > "But on a plain simple laptop or workstation which has CPU hotplug, > would it make sense for the crash ranges to get updated too when CPUs > are offlined? > > If so, I think you want this code present there too, without a Kconfig > item." > > IOW, if this thing doesn't make sense to have on the majority of > machines out there - and memory hotplug machines are not the majority - > then it should be behind a Kconfig item which is default off and gets > enabled only when the user selects crash and memory hotplug... > > I'd say. > Boris, I apologize for the delay in responding, I've been away for the past week. I'm re-reading the thread on this topic, and I apologize for backing up a bit, but as I read the last paragraph again, your contention is that the bit of code in this file *should* be behind a Kconfig item, and default to off, as "memory hotplug machines are not the majority". Does this mean then that I need to introduce CRASH_HOTPLUG again, so it can be default off? Examining arch/x86/configs/x86_64_defconfig, neither HOTPLUG_CPU or MEMORY_HOTPLUG are present, but CONFIG_SMP=y. And in examining arch/x86/Kconfig, I see: config HOTPLUG_CPU def_bool y depends on SMP which then defaults HOTPLUG_CPU to on and thus this code/ifdef in question. And as a reminder, the '#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_MEMORY_HOTPLUG)' shows up in only three locations: include/linux/kexec.h, kernel/crash_core.c and arch/x86/kernel/crash.c. And we resolved in this thread last week that this patch series is useful for cpu and/or memory hotplug. So at this point, I'm still not sure if you want the ifdef line: - removed altogether - transitioned to CRASH_HOTPLUG - leave as is If I could get clarity on that, that would be much appreciated! Thanks! eric
Powered by blists - more mailing lists