[tip: irq/urgent] irqchip/gic-v3-its: Flush ITS tables correctly in non-coherent GIC designs

["tip-bot2 for Fang Xiang" <tip-bot2@linutronix.de>]

The following commit has been merged into the irq/urgent branch of tip:

Commit-ID:     d3badb15613c14dd35d3495b1dde5c90fcd616dd
Gitweb:        https://git.kernel.org/tip/d3badb15613c14dd35d3495b1dde5c90fcd616dd
Author:        Fang Xiang <fangxiang3@xiaomi.com>
AuthorDate:    Mon, 30 Oct 2023 16:32:56 +08:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Mon, 06 Nov 2023 01:16:33 +01:00

irqchip/gic-v3-its: Flush ITS tables correctly in non-coherent GIC designs

In non-coherent GIC designs, the ITS tables must be flushed before writing
to the GITS_BASER<n> registers, otherwise the ITS could read dirty tables,
which results in unpredictable behavior.

Flush the tables right at the begin of its_setup_baser() to prevent that.

[ tglx: Massage changelog ]

Fixes: a8707f553884 ("irqchip/gic-v3: Add Rockchip 3588001 erratum workaround")
Suggested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Fang Xiang <fangxiang3@xiaomi.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20231030083256.4345-1-fangxiang3@xiaomi.com
---
 drivers/irqchip/irq-gic-v3-its.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index a8c89df..9a7a742 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -2379,12 +2379,12 @@ retry_baser:
 		break;
 	}
 
+	if (!shr)
+		gic_flush_dcache_to_poc(base, PAGE_ORDER_TO_SIZE(order));
+
 	its_write_baser(its, baser, val);
 	tmp = baser->val;
 
-	if (its->flags & ITS_FLAGS_FORCE_NON_SHAREABLE)
-		tmp &= ~GITS_BASER_SHAREABILITY_MASK;
-
 	if ((val ^ tmp) & GITS_BASER_SHAREABILITY_MASK) {
 		/*
 		 * Shareability didn't stick. Just use
@@ -2394,10 +2394,9 @@ retry_baser:
 		 * non-cacheable as well.
 		 */
 		shr = tmp & GITS_BASER_SHAREABILITY_MASK;
-		if (!shr) {
+		if (!shr)
 			cache = GITS_BASER_nC;
-			gic_flush_dcache_to_poc(base, PAGE_ORDER_TO_SIZE(order));
-		}
+
 		goto retry_baser;
 	}
 
@@ -2609,6 +2608,11 @@ static int its_alloc_tables(struct its_node *its)
 		/* erratum 24313: ignore memory access type */
 		cache = GITS_BASER_nCnB;
 
+	if (its->flags & ITS_FLAGS_FORCE_NON_SHAREABLE) {
+		cache = GITS_BASER_nC;
+		shr = 0;
+	}
+
 	for (i = 0; i < GITS_BASER_NR_REGS; i++) {
 		struct its_baser *baser = its->tables + i;
 		u64 val = its_read_baser(its, baser);