Messages in this thread Patch in this message | | | Date | Tue, 12 Apr 2016 11:06:37 -0700 (PDT) | From | Stefano Stabellini <> | Subject | Re: Xen regression, Was: [PATCH] x86/irq: Probe for PIC presence before allocating descs for legacy IRQs |
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On Tue, 12 Apr 2016, Boris Ostrovsky wrote: > On 04/11/2016 10:08 PM, Stefano Stabellini wrote: > > Hi all, > > > > Unfortunately this patch (now commit > > 8c058b0b9c34d8c8d7912880956543769323e2d8) causes a regression on Xen > > when running on top of QEMU: the number of PIT irqs get set to 0 by > > probe_8259A but actually there are 16. > > > > Any suggestions on how to fix this? > > > > 1) we could revert 8c058b0b9c34d8c8d7912880956543769323e2d8 > > 2) we could introduce an 'if (!xen_domain())' in probe_8259A > > 3) suggestions welcome > > Stefano, do you have b4ff8389ed14b849354b59ce9b360bdefcdbf99c ? > > It was supposed to fix this problem for Xen. However, I just noticed that > arch/arm64/include/asm/irq.h makes nr_legacy_irqs() return 0 (unlike > arch/arm/include/asm/irq.h). Could that be the problem?
I have b4ff8389ed14b849354b59ce9b360bdefcdbf99c but it doesn't fix the issue for me.
Is the idea of your patch that xen_allocate_irq_gsi will allocate the descriptor dynamically instead? If so, it doesn't work because it doesn't get called for irq 14:
piix_init_one -> ata_pci_sff_activate_host -> devm_request_irq -> devm_request_threaded_irq-> request_threaded_irq -> irq_to_desc(14) -> -EVAIL
If you look at pci_xen_initial_domain, the loop:
for (irq = 0; irq < nr_legacy_irqs(); irq++) {
won't work anymore because by the time is called, nr_legacy_irqs() already returns 0, because it has been changed by probe_8259A().
We also need the following patch:
---
xen/x86: actually allocate legacy interrupts on PV guests
b4ff8389ed14 is incomplete: relies on nr_legacy_irqs() to get the number of legacy interrupts when actually nr_legacy_irqs() returns 0 after probe_8259A(). Use NR_IRQS_LEGACY instead.
Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c index beac4df..6db0060 100644 --- a/arch/x86/pci/xen.c +++ b/arch/x86/pci/xen.c @@ -492,7 +492,7 @@ int __init pci_xen_initial_domain(void) __acpi_register_gsi = acpi_register_gsi_xen; __acpi_unregister_gsi = NULL; /* Pre-allocate legacy irqs */ - for (irq = 0; irq < nr_legacy_irqs(); irq++) { + for (irq = 0; irq < NR_IRQS_LEGACY; irq++) { int trigger, polarity; if (acpi_get_override_irq(irq, &trigger, &polarity) == -1)
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