Commit 26ab12bb authored Dec 01, 2020 by Dexuan Cui Committed by Thomas Gleixner Dec 02, 2020

iommu/hyper-v: Remove I/O-APIC ID check from hyperv_irq_remapping_select()



commit a491bb19 ("iommu/hyper-v: Implement select() method on remapping
irqdomain") restricted the irq_domain_ops::select() callback to match on
I/O-APIC index 0, which was correct until the parameter was changed to
carry the I/O APIC ID in commit f36a74b9.

If the ID is not 0 then the match fails. Therefore I/O-APIC init fails to
retrieve the parent irqdomain for the I/O-APIC resulting in a boot panic:

    kernel BUG at arch/x86/kernel/apic/io_apic.c:2408!

Fix it by matching the I/O-APIC independent of the ID as there is only one
I/O APIC emulated by Hyper-V.

[ tglx: Amended changelog ]

Fixes: f36a74b9 ("x86/ioapic: Use I/O-APIC ID for finding irqdomain, not index")
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20201202004510.1818-1-decui@microsoft.com

parent d1adcfbb

drivers/iommu/hyperv-iommu.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -105,8 +105,8 @@ static int hyperv_irq_remapping_select(struct irq_domain *d,
		struct irq_fwspec *fwspec,
		enum irq_domain_bus_token bus_token)
		{
		/* Claim only the first (and only) I/OAPIC */
		return x86_fwspec_is_ioapic(fwspec) && fwspec->param[0] == 0;
		/* Claim the only I/O APIC emulated by Hyper-V */
		return x86_fwspec_is_ioapic(fwspec);
		}

		static const struct irq_domain_ops hyperv_ir_domain_ops = {

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