linux-kernel - Re: [Xen-devel] [PATCH v3 4/4] xen/arm: account for stolen ticks

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: <1368087121.17285.86.camel@zakaz.uk.xensource.com>
Date:	Thu, 9 May 2013 09:12:01 +0100
From:	Ian Campbell <Ian.Campbell@...rix.com>
To:	Stefano Stabellini <stefano.stabellini@...citrix.com>
CC:	Marc Zyngier <marc.zyngier@....com>,
	"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>,
	"konrad.wilk@...cle.com" <konrad.wilk@...cle.com>,
	Will Deacon <Will.Deacon@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [Xen-devel] [PATCH v3 4/4] xen/arm: account for stolen ticks

On Wed, 2013-05-08 at 18:03 +0100, Stefano Stabellini wrote:
> > What if we have Xen support enabled but don't run as a Xen guest?
> 
> That's fine as long as the Xen runstate_memory_area interface is
> available.
> Usually I am a great fun of feature flags, so that every feature can be
> dynamically enabled or disabled and an hypervisor interface can be only
> partially implemented.
> 
> However the runstate_memory_area is very old and I would consider it
> one of the core interfaces that need to be available in order to claim
> "Xen compatibility".

I think Marc meant "what if CONFIG_XEN=y but we are running on KVM?". In
that case we wont have set either of the paravirt_steal*_enabled static
keys and so the hook won't be called.

> > > +	static_key_slow_inc(&paravirt_steal_enabled);
> > > +	static_key_slow_inc(&paravirt_steal_rq_enabled);
> > > +


Ian.

--
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/