linux-kernel - [PATCH v2 0/7] Various tsc/clocksource fixes

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

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20180430100008.503783478@infradead.org>
Date:   Mon, 30 Apr 2018 12:00:08 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     tglx@...utronix.de
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        diego.viola@...il.com, len.brown@...el.com, rjw@...ysocki.net,
        rui.zhang@...el.com
Subject: [PATCH v2 0/7] Various tsc/clocksource fixes

These patches are the result of the regression Diego reported against commit:

  aa83c45762a2 ("x86/tsc: Introduce early tsc clocksource")

His Core2 triggers mark_tsc_unstable() while we're running with tsc-early,
which then results in us failing to unregister the clocksource.

Furthermore, since mark_tsc_unstable() only looks at the regular tsc
clocksource, we don't even mark tsc_early UNSTABLE or de-rate it, resulting in
it actually staying a desirable clocksource.

Fixing that is a little more tricky; albeit far less critical after we
guarantee to unregister tsc-early.

Please consider these for /urgent. I've used both Fixes and stable tags
on a bunch of them because the above commit is already in v4.16 and
would need stable help.

These patches have been tested on both a Core2 and an IVB. On IVB I've both
changed intel_idle to always report the TSC unstable and mucked about with the
TSC msr from userspace to tickle the watchdog paths.

---
Changes since v1

 - fix __clocksource_change_rating() locking
 - removed work->kthread->watchdog hoops
 - fixed up comment