From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753195AbeASHVm (ORCPT ); Fri, 19 Jan 2018 02:21:42 -0500 Received: from mx1.redhat.com ([209.132.183.28]:34490 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750785AbeASHVd (ORCPT ); Fri, 19 Jan 2018 02:21:33 -0500 Date: Fri, 19 Jan 2018 15:21:30 +0800 From: Baoquan He To: Dou Liyang Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, tglx@linutronix.de, hpa@zytor.com, x86@kernel.org, rostedt@goodmis.org, jgross@suse.com, peterz@infradead.org, uobergfe@redhat.com, joro@8bytes.org Subject: Re: [RESEND PATCH 3/3] x86/apic: Clean up the names of legacy irq mode setting related functions Message-ID: <20180119072130.GG1753@localhost.localdomain> References: <1515123732-28908-1-git-send-email-bhe@redhat.com> <20180105043929.GL7235@x1> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/19/18 at 02:42pm, Dou Liyang wrote: > Hi Baoquan, > > At 01/05/2018 12:39 PM, Baoquan He wrote: > [...] > > /* > > - * Not an __init, needed by kexec/kdump code. > > - * For safety IO-APIC and Local APIC need be cleared before this. > > + * In legacy irq mode, full DOS compatibility with the uniprocessor PC/AT is > > + * provided by using the APICs in conjunction with standard 8259A-equivalent > > + * programmable interrupt controllers (PICs). It's necessary to deliver legacy > > + * interrupts even when APIC mode is not enabled. This is required by kexec/ > > + * kdump before enter into the 2nd kernel. > > */ > > void switch_to_legacy_irq_mode(void) > > { > > if (!nr_legacy_irqs()) > > return; > > - x86_io_apic_ops.disable(); > > + ioapic_set_virtual_wire_mode(); > > + > > + if (boot_cpu_has(X86_FEATURE_APIC) || apic_from_smp_config()) > > + lapic_set_legacy_irq_mode(ioapic_i8259.pin != -1); > > Seems these two function, ioapic/lapic_set_legacy_irq_mode should be > exclusive. Thanks for looking into this, dou! It might be not exclusive. You can see mp_spec 3.6.2.2 Virtual Wire Mode subsection, there are two kinds of virtual wire mode, one is 8259A-Equivalent pics is connected to lint0 of boot cpu LAPIC, the other is 8259A-Equivalent pics go through IO-APIC, then is connected to lint0 of LAPIC. Whatever it is, LAPIC need be set as through-lapic. Above is what I got from mp_spec. But from function native_disable_io_apic() and disconnect_bsp_APIC(), the code seems to be telling that if io-apic is connected to 8259A-Equivalent pics, we need mask lvt0 of LAPIC. This conflicts with mp_spec 3.6.2.2. Thanks Baoquan > > But We do that because both the through-lapic and through-ioapic virtual > wire mode need setup the APIC_SPIV_APIC_ENABLED which is only located in > the lapic_set_legacy_irq_mode(). So we need call them both. > > IMO, this cleanup may not make it clear. we can separate these two mode > totally or just keep it like before. > > Thanks, > dou. > > } > > #ifdef CONFIG_X86_32 > > diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c > > index 1151ccd72ce9..c30f0f273dbd 100644 > > --- a/arch/x86/kernel/x86_init.c > > +++ b/arch/x86/kernel/x86_init.c > > @@ -148,5 +148,5 @@ void arch_restore_msi_irqs(struct pci_dev *dev) > > struct x86_io_apic_ops x86_io_apic_ops __ro_after_init = { > > .read = native_io_apic_read, > > - .disable = native_disable_io_apic, > > + .disable = switch_to_legacy_irq_mode, > > }; > > diff --git a/drivers/iommu/irq_remapping.c b/drivers/iommu/irq_remapping.c > > index 49721b4e1975..751472ddf536 100644 > > --- a/drivers/iommu/irq_remapping.c > > +++ b/drivers/iommu/irq_remapping.c > > @@ -37,7 +37,7 @@ static void irq_remapping_disable_io_apic(void) > > * now. > > */ > > if (boot_cpu_has(X86_FEATURE_APIC) || apic_from_smp_config()) > > - disconnect_bsp_APIC(0); > > + lapic_set_legacy_irq_mode(0); > > } > > static void __init irq_remapping_modify_x86_ops(void) > > > >