From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757581AbcJXOc3 (ORCPT ); Mon, 24 Oct 2016 10:32:29 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49982 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756256AbcJXOc1 (ORCPT ); Mon, 24 Oct 2016 10:32:27 -0400 Subject: Re: [PATCH] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt() To: Wanpeng Li References: <1476409733-5133-1-git-send-email-wanpeng.li@hotmail.com> <20161016133911.GI3142@twins.programming.kicks-ass.net> <20161017082250.GX3568@worktop.programming.kicks-ass.net> <938757058.3991379.1476698922290.JavaMail.zimbra@redhat.com> <2d1e0bd3-5e5b-4a06-9005-327cc6364050@redhat.com> Cc: Peter Zijlstra , "linux-kernel@vger.kernel.org" , Wanpeng Li , Ingo Molnar , Mike Galbraith , Thomas Gleixner , Radim Krcmar From: Paolo Bonzini Message-ID: Date: Mon, 24 Oct 2016 16:32:19 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Mon, 24 Oct 2016 14:32:27 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 19/10/2016 16:30, Wanpeng Li wrote: > Cc Radim, > 2016-10-19 22:10 GMT+08:00 Paolo Bonzini : >> >> >> On 19/10/2016 16:01, Wanpeng Li wrote: >>> 2016-10-18 8:01 GMT+08:00 Wanpeng Li : >>>> 2016-10-17 18:08 GMT+08:00 Paolo Bonzini : >>>> [...] >>>>>>> Something like the below avoids all that. Paravirt will still need fixing. >>>>>> >>>>>> kvm_guest_apic_eoi_write >>>>>> -> native_apic_msr_write >>>>> >>>>> kvm_guest_apic_eoi_write can use native_apic_msr_eoi_write too: >>>>> >>>>> diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h >>>>> index f5aaf6c83222..9769d76a62c4 100644 >>>>> --- a/arch/x86/include/asm/apic.h >>>>> +++ b/arch/x86/include/asm/apic.h >>>>> @@ -174,7 +174,7 @@ static inline void disable_local_APIC(void) { } >>>>> static inline void lapic_update_tsc_freq(void) { } >>>>> #endif /* !CONFIG_X86_LOCAL_APIC */ >>>>> >>>>> -#ifdef CONFIG_X86_X2APIC >>>>> +#if defined CONFIG_X86_X2APIC || defined CONFIG_KVM_GUEST >>>> >>>> If CONFIG_X86_X2APIC is undefined and CONFIG_KVM_GUEST is defined, >>>> there are undefined reference warning for x2apic_mode and check_x2apic >>>> etc since they are extern variables and just define under >>>> CONFIG_X86_X2APIC. >>> > > This results in undefined reference warning. > >>> >>>> >>>> If -cpu host,-x2apic we should go through mmio when writes xapic EOI. >>> >>> Any ideas? :) >> >> Make apic_set_eoi_write return the old pointer? > > Could you elaborate? :) No, that won't work due to how struct apic works and how apic_set_eoi_write patches it. One possibility then is to add a void (*native_eoi_write)(u32 reg, u32 v); field to struct apic, and make apic_set_eoi_write set (*drv)->native_eoi_write = (*drv)->eoi_write; (*drv)->eoi_write = eoi_write; Then kvm.c can call apic->native_eoi_write(reg, v); Thanks, Paolo