[PATCH] irqchip/gic-v3-its: Add workaround for ThunderX2 erratum #174

[Ganapatrao Kulkarni]

When an interrupt is moved across node collections on ThunderX2
multi Socket platform, an interrupt stops routed to new collection
and results in loss of interrupts.

Adding workaround to issue INV after MOVI for cross-node collection
move to flush out the cached entry.

Signed-off-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@xxxxxxxxxx>
---
 Documentation/arm64/silicon-errata.txt |  1 +
 arch/arm64/Kconfig                     | 11 +++++++++++
 drivers/irqchip/irq-gic-v3-its.c       | 24 ++++++++++++++++++++++++
 3 files changed, 36 insertions(+)

diff --git a/Documentation/arm64/silicon-errata.txt b/Documentation/arm64/silicon-errata.txt
index fc1c884..fb27cb5 100644
--- a/Documentation/arm64/silicon-errata.txt
+++ b/Documentation/arm64/silicon-errata.txt
@@ -63,6 +63,7 @@ stable kernels.
 | Cavium         | ThunderX Core   | #27456          | CAVIUM_ERRATUM_27456        |
 | Cavium         | ThunderX Core   | #30115          | CAVIUM_ERRATUM_30115        |
 | Cavium         | ThunderX SMMUv2 | #27704          | N/A                         |
+| Cavium         | ThunderX2 ITS   | #174            | CAVIUM_ERRATUM_174          |
 | Cavium         | ThunderX2 SMMUv3| #74             | N/A                         |
 | Cavium         | ThunderX2 SMMUv3| #126            | N/A                         |
 |                |                 |                 |                             |
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index c9a7e9e..71a7e30 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -461,6 +461,17 @@ config ARM64_ERRATUM_843419
 
 	  If unsure, say Y.
 
+config CAVIUM_ERRATUM_174
+	bool "Cavium ThunderX2 erratum 174"
+	depends on NUMA
+	default y
+	help
+	  LPI stops routed to redistributors after inter node collection
+	  move in ITS. Enable workaround to invalidate ITS entry after
+	  inter-node collection move.
+
+	  If unsure, say Y.
+
 config CAVIUM_ERRATUM_22375
 	bool "Cavium erratum 22375, 24313"
 	default y
diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 06f025f..d8b9c96 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -46,6 +46,7 @@
 #define ITS_FLAGS_CMDQ_NEEDS_FLUSHING		(1ULL << 0)
 #define ITS_FLAGS_WORKAROUND_CAVIUM_22375	(1ULL << 1)
 #define ITS_FLAGS_WORKAROUND_CAVIUM_23144	(1ULL << 2)
+#define ITS_FLAGS_WORKAROUND_CAVIUM_174		(1ULL << 3)
 
 #define RDIST_FLAGS_PROPBASE_NEEDS_FLUSHING	(1 << 0)
 
@@ -1119,6 +1120,12 @@ static int its_set_affinity(struct irq_data *d, const struct cpumask *mask_val,
 	if (cpu != its_dev->event_map.col_map[id]) {
 		target_col = &its_dev->its->collections[cpu];
 		its_send_movi(its_dev, target_col, id);
+		if (its_dev->its->flags & ITS_FLAGS_WORKAROUND_CAVIUM_174) {
+			/* Issue INV for cross node collection move. */
+			if (cpu_to_node(cpu) !=
+				cpu_to_node(its_dev->event_map.col_map[id]))
+				its_send_inv(its_dev, id);
+		}
 		its_dev->event_map.col_map[id] = cpu;
 		irq_data_update_effective_affinity(d, cpumask_of(cpu));
 	}
@@ -2904,6 +2911,15 @@ static int its_force_quiescent(void __iomem *base)
 	}
 }
 
+static bool __maybe_unused its_enable_quirk_cavium_174(void *data)
+{
+	struct its_node *its = data;
+
+	its->flags |= ITS_FLAGS_WORKAROUND_CAVIUM_174;
+
+	return true;
+}
+
 static bool __maybe_unused its_enable_quirk_cavium_22375(void *data)
 {
 	struct its_node *its = data;
@@ -3031,6 +3047,14 @@ static const struct gic_quirk its_quirks[] = {
 		.init	= its_enable_quirk_hip07_161600802,
 	},
 #endif
+#ifdef CONFIG_CAVIUM_ERRATUM_174
+	{
+		.desc	= "ITS: Cavium ThunderX2 erratum 174",
+		.iidr	= 0x13f,	/* ThunderX2 pass A1/A2/B0 */
+		.mask	= 0xffffffff,
+		.init	= its_enable_quirk_cavium_174,
+	},
+#endif
 	{
 	}
 };
-- 
2.9.4