irqchip/gicv3-its: Avoid cache flush beyond ITS_BASERn memory size

Function its_alloc_tables() maintains two local variables, "order" and
and "alloc_size", to hold memory size that has been allocated to
ITS_BASEn. We don't always refresh the variable alloc_size whenever
value of the variable order changes, causing the following two
problems.

  - Cache flush operation with size more than required.
  - Information reported by pr_info is not correct.

Use a helper macro that converts page order to size in bytes instead of
variable "alloc_size" to fix both the problems.
Signed-off-by: Shanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

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

@@ -78,6 +78,9 @@ struct its_node {
 
 #define ITS_ITT_ALIGN		SZ_256
 
+/* Convert page order to size in bytes */
+#define PAGE_ORDER_TO_SIZE(o)	(PAGE_SIZE << (o))
+
 struct event_lpi_map {
 	unsigned long		*lpi_map;
 	u16			*col_map;
@@ -841,7 +844,6 @@ static int its_alloc_tables(const char *node_name, struct its_node *its)
 		u64 type = GITS_BASER_TYPE(val);
 		u64 entry_size = GITS_BASER_ENTRY_SIZE(val);
 		int order = get_order(psz);
-		int alloc_size;
 		int alloc_pages;
 		u64 tmp;
 		void *base;
@@ -873,9 +875,8 @@ static int its_alloc_tables(const char *node_name, struct its_node *its)
 			}
 		}
 
-		alloc_size = (1 << order) * PAGE_SIZE;
 retry_alloc_baser:
-		alloc_pages = (alloc_size / psz);
+		alloc_pages = (PAGE_ORDER_TO_SIZE(order) / psz);
 		if (alloc_pages > GITS_BASER_PAGES_MAX) {
 			alloc_pages = GITS_BASER_PAGES_MAX;
 			order = get_order(GITS_BASER_PAGES_MAX * psz);
@@ -928,7 +929,7 @@ static int its_alloc_tables(const char *node_name, struct its_node *its)
 			shr = tmp & GITS_BASER_SHAREABILITY_MASK;
 			if (!shr) {
 				cache = GITS_BASER_nC;
-				__flush_dcache_area(base, alloc_size);
+				__flush_dcache_area(base, PAGE_ORDER_TO_SIZE(order));
 			}
 			goto retry_baser;
 		}
@@ -961,7 +962,7 @@ static int its_alloc_tables(const char *node_name, struct its_node *its)
 		}
 
 		pr_info("ITS: allocated %d %s @%lx (psz %dK, shr %d)\n",
-			(int)(alloc_size / entry_size),
+			(int)(PAGE_ORDER_TO_SIZE(order) / entry_size),
 			its_base_type_string[type],
 			(unsigned long)virt_to_phys(base),
 			psz / SZ_1K, (int)shr >> GITS_BASER_SHAREABILITY_SHIFT);