linux-kernel - Re: [KVM timekeeping 05/35] Move TSC reset out of vmcb

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: <20100820170849.GC2937@mothafucka.localdomain>
Date:	Fri, 20 Aug 2010 14:08:49 -0300
From:	Glauber Costa <glommer@...hat.com>
To:	Zachary Amsden <zamsden@...hat.com>
Cc:	kvm@...r.kernel.org, Avi Kivity <avi@...hat.com>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	John Stultz <johnstul@...ibm.com>, linux-kernel@...r.kernel.org
Subject: Re: [KVM timekeeping 05/35] Move TSC reset out of vmcb_init

On Thu, Aug 19, 2010 at 10:07:19PM -1000, Zachary Amsden wrote:
> The VMCB is reset whenever we receive a startup IPI, so Linux is setting
> TSC back to zero happens very late in the boot process and destabilizing
> the TSC.  Instead, just set TSC to zero once at VCPU creation time.
> 
> Why the separate patch?  So git-bisect is your friend.
> 
> Signed-off-by: Zachary Amsden <zamsden@...hat.com>
Shouldn't we set for whatever value the BSP already has, and then the BSP to
zero? Since vcpus are initialized at different times, this pretty much
guarantees that the guest will have desynchronized tsc at all cases
(not that if it was better before...)
--
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/