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x86/idt: Keep spurious entries unset in system_vectors

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With commit dc20b2d526 ("x86/idt: Move interrupt gate initialization to
IDT code") non assigned system vectors are also marked as used in
'used_vectors' (now 'system_vectors') bitmap. This makes checks in
arch_show_interrupts() whether a particular system vector is allocated to
always pass and e.g. 'Hyper-V reenlightenment interrupts' entry always
shows up in /proc/interrupts.

Another side effect of having all unassigned system vectors marked as used
is that irq_matrix_debug_show() will wrongly count them among 'System'
vectors.

As it is now ensured that alloc_intr_gate() is not called after init, it is
possible to leave unused entries in 'system_vectors' unset to fix these
issues.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200428093824.1451532-4-vkuznets@redhat.com
This commit is contained in:
Vitaly Kuznetsov 2020-04-28 11:38:24 +02:00 committed by Thomas Gleixner
parent 06184325a1
commit 1f1fbc70c1
1 changed files with 5 additions and 1 deletions
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6
arch/x86/kernel/idt.c
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@ -321,7 +321,11 @@ void __init idt_setup_apic_and_irq_gates(void)
#ifdef CONFIG_X86_LOCAL_APIC
for_each_clear_bit_from(i, system_vectors, NR_VECTORS) {
set_bit(i, system_vectors);
/*
* Don't set the non assigned system vectors in the
* system_vectors bitmap. Otherwise they show up in
* /proc/interrupts.
*/
entry = spurious_entries_start + 8 * (i - FIRST_SYSTEM_VECTOR);
set_intr_gate(i, entry);
}