genirq/irqdomain: Add force reactivation flag to irq domains

Allow irqdomains to tell the core code, that after early activation the
interrupt needs to be reactivated at request_irq() time.

This allows reservation of vectors at early activation time and actual
vector assignment at request_irq() time.
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/20170913213153.106242536@linutronix.de

include/linux/msi.h

@@ -283,6 +283,11 @@ enum {
 	MSI_FLAG_PCI_MSIX		= (1 << 3),
 	/* Needs early activate, required for PCI */
 	MSI_FLAG_ACTIVATE_EARLY		= (1 << 4),
+	/*
+	 * Must reactivate when irq is started even when
+	 * MSI_FLAG_ACTIVATE_EARLY has been set.
+	 */
+	MSI_FLAG_MUST_REACTIVATE	= (1 << 5),
 };
 
 int msi_domain_set_affinity(struct irq_data *data, const struct cpumask *mask,

kernel/irq/msi.c

@@ -404,6 +404,8 @@ int msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev,
 			ret = irq_domain_activate_irq(irq_data, true);
 			if (ret)
 				goto cleanup;
+			if (info->flags & MSI_FLAG_MUST_REACTIVATE)
+				irqd_clr_activated(irq_data);
 		}
 	}
 	return 0;