irqchip/gic-v3-its: Split out property table allocation

Move the LPI property table allocation into its own function, as
this is going to be required for those associated with VMs in
the future.
Reviewed-by: NEric Auger <eric.auger@redhat.com>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

drivers/irqchip/irq-gic-v3-its.c

@@ -905,13 +905,32 @@ static void its_lpi_free(struct event_lpi_map *map)
 	kfree(map->col_map);
 }
 
+static struct page *its_allocate_prop_table(gfp_t gfp_flags)
+{
+	struct page *prop_page;
+
+	prop_page = alloc_pages(gfp_flags, get_order(LPI_PROPBASE_SZ));
+	if (!prop_page)
+		return NULL;
+
+	/* Priority 0xa0, Group-1, disabled */
+	memset(page_address(prop_page),
+	       LPI_PROP_DEFAULT_PRIO | LPI_PROP_GROUP1,
+	       LPI_PROPBASE_SZ);
+
+	/* Make sure the GIC will observe the written configuration */
+	gic_flush_dcache_to_poc(page_address(prop_page), LPI_PROPBASE_SZ);
+
+	return prop_page;
+}
+
+
 static int __init its_alloc_lpi_tables(void)
 {
 	phys_addr_t paddr;
 
 	lpi_id_bits = min_t(u32, gic_rdists->id_bits, ITS_MAX_LPI_NRBITS);
-	gic_rdists->prop_page = alloc_pages(GFP_NOWAIT,
-					   get_order(LPI_PROPBASE_SZ));
+	gic_rdists->prop_page = its_allocate_prop_table(GFP_NOWAIT);
 	if (!gic_rdists->prop_page) {
 		pr_err("Failed to allocate PROPBASE\n");
 		return -ENOMEM;
@@ -920,14 +939,6 @@ static int __init its_alloc_lpi_tables(void)
 	paddr = page_to_phys(gic_rdists->prop_page);
 	pr_info("GIC: using LPI property table @%pa\n", &paddr);
 
-	/* Priority 0xa0, Group-1, disabled */
-	memset(page_address(gic_rdists->prop_page),
-	       LPI_PROP_DEFAULT_PRIO | LPI_PROP_GROUP1,
-	       LPI_PROPBASE_SZ);
-
-	/* Make sure the GIC will observe the written configuration */
-	gic_flush_dcache_to_poc(page_address(gic_rdists->prop_page), LPI_PROPBASE_SZ);
-
 	return its_lpi_init(lpi_id_bits);
 }