Commit 1f1fbc70 authored Apr 28, 2020 by Vitaly Kuznetsov Committed by Thomas Gleixner Jun 11, 2020

x86/idt: Keep spurious entries unset in system_vectors



With commit dc20b2d5 ("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

parent 06184325

arch/x86/kernel/idt.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -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);
		}

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