linux-kernel - Re: [PATCH v4] x86/power: Fix 'nosmt' vs. hibernation triple fault during resume

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

Message-ID: <nycvar.YFH.7.76.1905311651450.1962@cbobk.fhfr.pm>
Date:   Fri, 31 May 2019 16:54:20 +0200 (CEST)
From:   Jiri Kosina <jikos@...nel.org>
To:     Andy Lutomirski <luto@...capital.net>
cc:     Andy Lutomirski <luto@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        the arch/x86 maintainers <x86@...nel.org>,
        Pavel Machek <pavel@....cz>, Ingo Molnar <mingo@...hat.com>,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4] x86/power: Fix 'nosmt' vs. hibernation triple fault
 during resume

On Fri, 31 May 2019, Andy Lutomirski wrote:

> For that matter, what actually happens if we get an SMI while halted?  
> Does RSM go directly to sleep or does it re-fetch the HLT?

Our mails just crossed, I replied to Josh's mwait() proposal patch a 
minute ago.

HLT is guaranteed to be re-entered if SMM interrupted it, while MWAIT is 
not.

So as a short-term fix for 5.2, I still believe in v4 of my patch that 
does the mwait->hlt->mwait transition across hibernate/resume, and for 5.3 
I can look into forcing it to wait-for-SIPI proper.

-- 
Jiri Kosina
SUSE Labs