irqchip/gic-v3-its: Give the percpu rdist struct its own flags field

Later patches will require tracking some per-rdist status. Reuse the bytes
"lost" to padding within the __percpu rdist struct as a flags field, and
re-encode ->lpi_enabled within said flags.

No change in functionality intended.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211027151506.2085066-2-valentin.schneider@arm.com

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

@@ -46,6 +46,8 @@
 #define RDIST_FLAGS_PROPBASE_NEEDS_FLUSHING	(1 << 0)
 #define RDIST_FLAGS_RD_TABLES_PREALLOCATED	(1 << 1)
 
+#define RD_LOCAL_LPI_ENABLED                    BIT(0)
+
 static u32 lpi_id_bits;
 
 /*
@@ -3044,7 +3046,7 @@ static void its_cpu_init_lpis(void)
 	phys_addr_t paddr;
 	u64 val, tmp;
 
-	if (gic_data_rdist()->lpi_enabled)
+	if (gic_data_rdist()->flags & RD_LOCAL_LPI_ENABLED)
 		return;
 
 	val = readl_relaxed(rbase + GICR_CTLR);
@@ -3158,7 +3160,7 @@ static void its_cpu_init_lpis(void)
 	/* Make sure the GIC has seen the above */
 	dsb(sy);
 out:
-	gic_data_rdist()->lpi_enabled = true;
+	gic_data_rdist()->flags |= RD_LOCAL_LPI_ENABLED;
 	pr_info("GICv3: CPU%d: using %s LPI pending table @%pa\n",
 		smp_processor_id(),
 		gic_data_rdist()->pend_page ? "allocated" : "reserved",
@@ -5138,7 +5140,7 @@ static int redist_disable_lpis(void)
 	 *
 	 * If running with preallocated tables, there is nothing to do.
 	 */
-	if (gic_data_rdist()->lpi_enabled ||
+	if ((gic_data_rdist()->flags & RD_LOCAL_LPI_ENABLED) ||
 	    (gic_rdists->flags & RDIST_FLAGS_RD_TABLES_PREALLOCATED))
 		return 0;
 

include/linux/irqchip/arm-gic-v3.h

@@ -615,7 +615,7 @@ struct rdists {
 		void __iomem	*rd_base;
 		struct page	*pend_page;
 		phys_addr_t	phys_base;
-		bool		lpi_enabled;
+		u64             flags;
 		cpumask_t	*vpe_table_mask;
 		void		*vpe_l1_base;
 	} __percpu		*rdist;