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) > > > >