x86/apic: Mark _all_ legacy interrupts when IO/APIC is missing
PIC interrupts do not support affinity setting and they can end up on any online CPU. Therefore, it's required to mark the associated vectors as system-wide reserved. Otherwise, the corresponding irq descriptors are copied to the secondary CPUs but the vectors are not marked as assigned or reserved. This works correctly for the IO/APIC case. When the IO/APIC is disabled via config, kernel command line or lack of enumeration then all legacy interrupts are routed through the PIC, but nothing marks them as system-wide reserved vectors. As a consequence, a subsequent allocation on a secondary CPU can result in allocating one of these vectors, which triggers the BUG() in apic_update_vector() because the interrupt descriptor slot is not empty. Imran tried to work around that by marking those interrupts as allocated when a CPU comes online. But that's wrong in case that the IO/APIC is available and one of the legacy interrupts, e.g. IRQ0, has been switched to PIC mode because then marking them as allocated will fail as they are already marked as system vectors. Stay consistent and update the legacy vectors after attempting IO/APIC initialization and mark them as system vectors in case that no IO/APIC is available. Fixes: 69cde000 ("x86/vector: Use matrix allocator for vector assignment") Reported-by:Imran Khan <imran.f.khan@oracle.com> Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> Signed-off-by:
Borislav Petkov <bp@suse.de> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20210519233928.2157496-1-imran.f.khan@oracle.com
parent
c4681547
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