genirq/msi: Add size info to struct msi_domain_info

To allow proper range checking especially for dynamic allocations add a
size field to struct msi_domain_info. If the field is 0 then the size is
unknown or unlimited (up to MSI_MAX_INDEX) to provide backwards
compability.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221124232325.501144862@linutronix.de

include/linux/msi.h

@@ -422,6 +422,10 @@ struct msi_domain_ops {
  * struct msi_domain_info - MSI interrupt domain data
  * @flags:		Flags to decribe features and capabilities
  * @bus_token:		The domain bus token
+ * @hwsize:		The hardware table size or the software index limit.
+ *			If 0 then the size is considered unlimited and
+ *			gets initialized to the maximum software index limit
+ *			by the domain creation code.
  * @ops:		The callback data structure
  * @chip:		Optional: associated interrupt chip
  * @chip_data:		Optional: associated interrupt chip data
@@ -433,6 +437,7 @@ struct msi_domain_ops {
 struct msi_domain_info {
 	u32				flags;
 	enum irq_domain_bus_token	bus_token;
+	unsigned int			hwsize;
 	struct msi_domain_ops		*ops;
 	struct irq_chip			*chip;
 	void				*chip_data;

kernel/irq/msi.c

@@ -772,6 +772,17 @@ struct irq_domain *msi_create_irq_domain(struct fwnode_handle *fwnode,
 {
 	struct irq_domain *domain;
 
+	if (info->hwsize > MSI_XA_DOMAIN_SIZE)
+		return NULL;
+
+	/*
+	 * Hardware size 0 is valid for backwards compatibility and for
+	 * domains which are not backed by a hardware table. Grant the
+	 * maximum index space.
+	 */
+	if (!info->hwsize)
+		info->hwsize = MSI_XA_DOMAIN_SIZE;
+
 	msi_domain_update_dom_ops(info);
 	if (info->flags & MSI_FLAG_USE_DEF_CHIP_OPS)
 		msi_domain_update_chip_ops(info);