From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [patch 3/3] kvm-s390: provide general purpose registers via kvm_run Date: Thu, 22 Dec 2011 14:46:08 +0200 Message-ID: <4EF32690.6050605@redhat.com> References: <20111222115646.248800653@de.ibm.com> <20111222120054.367076904@de.ibm.com> <4EF323DB.5000203@redhat.com> <4EF32509.80200@de.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Marcelo Tossati , Carsten Otte , Alexander Graf , Jens Freimann , Cornelia Huck , Heiko Carstens , Martin Schwidefsky , KVM To: Christian Borntraeger Return-path: Received: from mx1.redhat.com ([209.132.183.28]:61550 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752616Ab1LVMqT (ORCPT ); Thu, 22 Dec 2011 07:46:19 -0500 In-Reply-To: <4EF32509.80200@de.ibm.com> Sender: kvm-owner@vger.kernel.org List-ID: On 12/22/2011 02:39 PM, Christian Borntraeger wrote: > On 22/12/11 13:34, Avi Kivity wrote: > >> The general purpose registers are often necessary to handle SIE exits. > >> Avoid additional ioctls by providing the guest registers in the r/w > >> section of the kvm_run structure. > >> > > > > This is only needed for S390_UCONTROL? > > No for the standard path. It was more like a "we copy the regs around > anyway inside the kernel, so why not use kvm_run as a place to store > the guest regs". So I will probably also have a look at floating point > regs and access registers. Sure, for side effect free registers that's a good approach. I'd copy it for x86, except vmx keeps %rsp cached in the cpu and won't let it out except via an expensive instruction, and also because it's very rarely used (mostly by "info registers" in qemu and live migration). -- error compiling committee.c: too many arguments to function