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

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index a8c89df1a997866c31238d94bb5cd26c5acf8dcb..9a7a74239eabb7cd3d2a3a077316d54833ec18cb 100644 (file)
--- 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);