linux-kernel - Re: [PATCH][KVM][retry 3] Add support for Pause Filtering to AMD SVM

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: <1242809657.26820.559.camel@twins>
Date:	Wed, 20 May 2009 10:54:17 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Avi Kivity <avi@...hat.com>
Cc:	Mark Langsdorf <mark.langsdorf@....com>,
	Joerg Roedel <joerg.roedel@....com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH][KVM][retry 3] Add support for Pause Filtering to AMD
 SVM

On Wed, 2009-05-20 at 11:49 +0300, Avi Kivity wrote:
> Peter Zijlstra wrote:
> >>> That said, I still thoroughly dislike this whole approach.
> >>>   
> >>>       
> >> Can you explain why?  We have a thread that has detected that it's 
> >> spinning.  Keeping on spinning is a waste of cpu time.  Why not let 
> >> something else use the cpu?
> >>     
> >
> > Because its a polling interface. I much prefer it if we were to get a
> > wakeup notification when the vcpu holding the lock releases it.
> >   
> 
> It's a fully virtualized guest.  There's no way to get this without 
> patching the guest kernel.

Yes there is.. virtualized monitor-wait stuff coupled with a
monitor-wait based spinlock implementation.

Once we go change silicon, you might as well do it right.
--
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/