Messages in this thread | | | Date | Fri, 19 Jan 2018 17:22:23 +0800 | From | Baoquan He <> | Subject | Re: [RESEND PATCH 3/3] x86/apic: Clean up the names of legacy irq mode setting related functions |
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On 01/19/18 at 04:06pm, Dou Liyang wrote: > > > At 01/19/2018 03:21 PM, Baoquan He wrote: > > 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 > > Oops! Sorry to confuse you, here what I want to say is that the code > make me think that we set through IO-APIC first, then set through > Local-APIC then. But, we can be only in one mode of them. > > Just worry about this code seems ignore the irq remapping situation. > > We call switch_to_legacy_irq_mode() directly in machine_kexec(), > why we also set x86_io_apic_ops: > > .disable = switch_to_legacy_irq_mode
You are right, this is not very clear. Since we call switch_to_legacy_irq_mode() directly, nobody will call x86_io_apic_ops.disable() any more.
Should keep native_disable_io_apic() and let x86_io_apic_ops.disable() to point at it.
Thanks Baoquan > > > 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. > > > > Yes, Absolutely right! > > > 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. > > > > I think so. > > Thanks, > dou. > > 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) > > > > > > > > > > > > > > > > > >
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