x86/ioapic: Mark legacy vectors at reallocation time

When the legacy PIC vectors are taken over by the IO APIC the current
vector assignement code is tricked to reuse the vector by allocating the
apic data in the early boot process. This can be avoided by marking the
allocation as legacy PIC take over. Preparatory patch for further cleanups.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Yu Chen <yu.c.chen@intel.com>
Acked-by: Juergen Gross <jgross@suse.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Alok Kataria <akataria@vmware.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rui Zhang <rui.zhang@intel.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Len Brown <lenb@kernel.org>
Link: https://lkml.kernel.org/r/20170913213154.700501979@linutronix.de

arch/x86/include/asm/irqdomain.h

@@ -8,6 +8,7 @@
 enum {
 	/* Allocate contiguous CPU vectors */
 	X86_IRQ_ALLOC_CONTIGUOUS_VECTORS		= 0x1,
+	X86_IRQ_ALLOC_LEGACY				= 0x2,
 };
 
 extern struct irq_domain *x86_vector_domain;

arch/x86/kernel/apic/io_apic.c

@@ -1013,6 +1013,7 @@ static int alloc_isa_irq_from_domain(struct irq_domain *domain,
 					  info->ioapic_pin))
 			return -ENOMEM;
 	} else {
+		info->flags |= X86_IRQ_ALLOC_LEGACY;
 		irq = __irq_domain_alloc_irqs(domain, irq, 1, node, info, true,
 					      NULL);
 		if (irq >= 0) {