From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757734Ab2EAD0F (ORCPT ); Mon, 30 Apr 2012 23:26:05 -0400 Received: from e23smtp04.au.ibm.com ([202.81.31.146]:51807 "EHLO e23smtp04.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753701Ab2EAD0C (ORCPT ); Mon, 30 Apr 2012 23:26:02 -0400 From: Nikunj A Dadhania To: Raghavendra K T Cc: peterz@infradead.org, mingo@elte.hu, jeremy@goop.org, mtosatti@redhat.com, kvm@vger.kernel.org, x86@kernel.org, vatsa@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, avi@redhat.com, hpa@zytor.com Subject: Re: [RFC PATCH v1 1/5] KVM Guest: Add VCPU running/pre-empted state for guest In-Reply-To: <4F9F367F.8090603@linux.vnet.ibm.com> References: <20120427161727.27082.43096.stgit@abhimanyu> <20120427162314.27082.13703.stgit@abhimanyu> <4F9F367F.8090603@linux.vnet.ibm.com> User-Agent: Notmuch/0.10.2+70~gf0e0053 (http://notmuchmail.org) Emacs/24.0.95.1 (x86_64-unknown-linux-gnu) Date: Tue, 01 May 2012 08:55:20 +0530 Message-ID: <87y5pch9b3.fsf@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain x-cbid: 12043017-9264-0000-0000-0000015DE2E1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 01 May 2012 06:33:59 +0530, Raghavendra K T wrote: > On 04/27/2012 09:53 PM, Nikunj A. Dadhania wrote: > > The patch adds guest code for msr between guest and hypervisor. The > > msr will export the vcpu running/pre-empted information to the guest > > from host. This will enable guest to intelligently send ipi to running > > vcpus and set flag for pre-empted vcpus. This will prevent waiting for > > vcpus that are not running. > > > > Suggested-by: Peter Zijlstra > > Signed-off-by: Nikunj A. Dadhania > > --- > > arch/x86/include/asm/kvm_para.h | 10 ++++++++++ > > arch/x86/kernel/kvm.c | 33 +++++++++++++++++++++++++++++++++ > > 2 files changed, 43 insertions(+), 0 deletions(-) > > > > diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h > > index 77266d3..f57b5cc 100644 > > --- a/arch/x86/include/asm/kvm_para.h > > +++ b/arch/x86/include/asm/kvm_para.h > > @@ -24,6 +24,7 @@ > > #define KVM_FEATURE_ASYNC_PF 4 > > #define KVM_FEATURE_STEAL_TIME 5 > > #define KVM_FEATURE_PV_UNHALT 6 > > +#define KVM_FEATURE_VCPU_STATE 7 > > I think you intended to use KVM_FEATURE_VCPU_STATE to address > guest/host compatibility issue so that host/guest does not break > when one of them run older kernel? > Yes, thats correct. Regards Nikunj