[PATCH] x86/ioapic: Use I/OAPIC ID for finding irqdomain, not index

[David Woodhouse]

From: David Woodhouse <d...@amazon.co.uk>

In commit b643128b917 ("x86/ioapic: Use irq_find_matching_fwspec() to
find remapping irqdomain") the I/OAPIC code was changed to find its
parent irqdomain using irq_find_matching_fwspec(), but the key used
for the lookup was wrong. It shouldn't use 'ioapic' which is the index
into its own ioapics[] array. It should use the actual arbitration
ID of the I/OAPIC in question, which is mpc_ioapic_id(ioapic).

Fixes: b643128b917 ("x86/ioapic: Use irq_find_matching_fwspec() to find 
remapping irqdomain")
Reported-by: lkp <oliver.s...@intel.com>
Signed-off-by: David Woodhouse <d...@amazon.co.uk>
---

The X2APIC_OPT_OUT bit was a red herring. Once I spotted and set up a
repro case such that mpc_ioapic_id(N) != N I can see it here. 


 arch/x86/kernel/apic/io_apic.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 443d2c9086b9..0d68e7c286e2 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2335,14 +2335,14 @@ static int mp_irqdomain_create(int ioapic)
        if (cfg->dev) {
                fn = of_node_to_fwnode(cfg->dev);
        } else {
-               fn = irq_domain_alloc_named_id_fwnode("IO-APIC", ioapic);
+               fn = irq_domain_alloc_named_id_fwnode("IO-APIC", 
mpc_ioapic_id(ioapic));
                if (!fn)
                        return -ENOMEM;
        }
 
        fwspec.fwnode = fn;
        fwspec.param_count = 1;
-       fwspec.param[0] = ioapic;
+       fwspec.param[0] = mpc_ioapic_id(ioapic);
 
        parent = irq_find_matching_fwspec(&fwspec, DOMAIN_BUS_ANY);
        if (!parent) {
-- 
2.17.1

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