Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752714Ab2FRPCO (ORCPT ); Mon, 18 Jun 2012 11:02:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34818 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752441Ab2FRPCN (ORCPT ); Mon, 18 Jun 2012 11:02:13 -0400 Message-ID: <4FDF42E7.8050902@redhat.com> Date: Mon, 18 Jun 2012 18:01:59 +0300 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120605 Thunderbird/13.0 MIME-Version: 1.0 To: "Michael S. Tsirkin" CC: x86@kernel.org, kvm@vger.kernel.org, Ingo Molnar , "H. Peter Anvin" , Marcelo Tosatti , gleb@redhat.com, Linus Torvalds , linux-kernel@vger.kernel.org, Thomas Gleixner Subject: Re: [PATCHv7 3/8] kvm_para: guest side for eoi avoidance References: <4c5bedc5cb55dcea1676b913a0f6da3f04b03145.1339681762.git.mst@redhat.com> <4FDF3874.2050208@redhat.com> <20120618145041.GE26540@redhat.com> In-Reply-To: <20120618145041.GE26540@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1742 Lines: 59 On 06/18/2012 05:50 PM, Michael S. Tsirkin wrote: > >> > >> > +/* size alignment is implied but just to make it explicit. */ >> > +static DEFINE_PER_CPU(unsigned long, kvm_apic_eoi) __aligned(2) = >> > + KVM_PV_EOI_DISABLED; >> >> You're actually breaking the alignment. ulong has 8 byte alignment >> sometimes and you can make it cross cache boundary this way. > > No, if you look at the definition of __aligned > you will see that it limits the alignment from below. > Compiler still applies the natural size alignment. > You are not the first to get confused. So I wonder: is it better > to add a comment or simply remove __aligned here. Both. >> > >> > + if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) { >> > + __get_cpu_var(kvm_apic_eoi) = 0; >> > + wrmsrl(MSR_KVM_PV_EOI_EN, __pa(&__get_cpu_var(kvm_apic_eoi)) | >> > + KVM_MSR_ENABLED); >> >> Bad formatting. > > I guess temporary will make it prettier. > unsigned long pa; > __get_cpu_var(kvm_apic_eoi) = 0; > pa = __pa(&__get_cpu_var(kvm_apic_eoi)) | KVM_MSR_ENABLED; > wrmsrl(MSR_KVM_PV_EOI_EN, pa); That, or + wrmsrl(MSR_KVM_PV_EOI_EN, + __pa(&__get_cpu_var(kvm_apic_eoi)) | _ENABLED); You have an argument split over two lines with no helpful indentation to show this. >> >> >> Please check that the kexec path also disables pveoi. > > The chunk in kvm_pv_guest_cpu_reboot does this, doesn't it? Dunno, does it? -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/