linux-kernel - Re: [Xen-devel] [PATCH 1/4] xen: disable non-boot VCPUs during suspend

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]

Date:	Thu, 20 Jun 2013 11:38:25 +0100
From:	"Jan Beulich" <JBeulich@...e.com>
To:	"David Vrabel" <david.vrabel@...rix.com>
Cc:	"John Stultz" <john.stultz@...aro.org>,
	"Thomas Gleixner" <tglx@...utronix.de>, <xen-devel@...ts.xen.org>,
	"Konrad Rzeszutek Wilk" <konrad.wilk@...cle.com>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [Xen-devel] [PATCH 1/4] xen: disable non-boot VCPUs during
 suspend

>>> On 19.06.13 at 17:25, David Vrabel <david.vrabel@...rix.com> wrote:
> syscore_suspend() and syscore_resume() expect there to be only one
> online CPU.  e.g., hrtimers_resume() only triggers events for the
> current CPU.  Xen's suspend path was leaving all VCPUs online and then
> attempting to fixup problems afterwards (e.g., with an explicit call
> to clock_was_set() to trigger pending high resolution timers).
> 
> Instead, disable non-boot CPUs before calling stop_machine() and
> reenable them afterwards.

In XenoLinux the so called "fast suspend" mode was specifically
added for performance reasons, and it looks like to date pv-ops
only ever supported that mode. So one question is whether
there's going to be any bad performance effect from this.

The other question is that about retaining the use of
stop_machine() then - it seems pretty pointless if you already
bring down all other CPUs.

Jan

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/