[RFC PATCH v2 08/10] riscv: Introduce HEST SSE notification handlers

[Himanshu Chauhan <hchauhan@ventanamicro.com>]

Add config option to enable SSE in APEI. When it is enabled, functions
to register/unregister a ghes entry with SSE are avilable along with
low and high priority event handers. If a SSE notification type is
determined, a ghes common handler to handle an error event is registered.

Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.com>
---
 drivers/acpi/apei/Kconfig |   5 ++
 drivers/acpi/apei/ghes.c  | 101 +++++++++++++++++++++++++++++++++-----
 2 files changed, 95 insertions(+), 11 deletions(-)

diff --git a/drivers/acpi/apei/Kconfig b/drivers/acpi/apei/Kconfig
index 070c07d68dfb..ada95a50805f 100644
--- a/drivers/acpi/apei/Kconfig
+++ b/drivers/acpi/apei/Kconfig
@@ -46,6 +46,11 @@ config ACPI_APEI_SEA
 	depends on ARM64 && ACPI_APEI_GHES
 	default y
 
+config ACPI_APEI_SSE
+	bool
+	depends on RISCV && RISCV_SBI_SSE && ACPI_APEI_GHES
+	default y
+
 config ACPI_APEI_MEMORY_FAILURE
 	bool "APEI memory error recovering support"
 	depends on ACPI_APEI && MEMORY_FAILURE
diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index f2cbd7414faf..3c47249245d1 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -17,6 +17,8 @@
  *   Author: Huang Ying <ying.huang@intel.com>
  */
 
+#include <linux/err.h>
+#include <linux/riscv_sbi_sse.h>
 #include <linux/arm_sdei.h>
 #include <linux/kernel.h>
 #include <linux/moduleparam.h>
@@ -97,6 +99,11 @@
 #define FIX_APEI_GHES_SDEI_CRITICAL	__end_of_fixed_addresses
 #endif
 
+#ifndef CONFIG_RISCV_SBI_SSE
+#define FIX_APEI_GHES_SSE_LOW_PRIORITY	__end_of_fixed_addresses
+#define FIX_APEI_GHES_SSE_HIGH_PRIORITY	__end_of_fixed_addresses
+#endif
+
 static ATOMIC_NOTIFIER_HEAD(ghes_report_chain);
 
 static inline bool is_hest_type_generic_v2(struct ghes *ghes)
@@ -1530,6 +1537,63 @@ static int apei_sdei_unregister_ghes(struct ghes *ghes)
 	return sdei_unregister_ghes(ghes);
 }
 
+#if defined(CONFIG_ACPI_APEI_SSE)
+/* SSE Handlers */
+static int __ghes_sse_callback(struct ghes *ghes,
+			       enum fixed_addresses fixmap_idx)
+{
+	if (!ghes_in_nmi_queue_one_entry(ghes, fixmap_idx)) {
+		irq_work_queue(&ghes_proc_irq_work);
+
+		return 0;
+	}
+
+	return -ENOENT;
+}
+
+/* Low priority */
+static int ghes_sse_lo_callback(u32 event_num, void *arg, struct pt_regs *regs)
+{
+	static DEFINE_RAW_SPINLOCK(ghes_notify_lock_sse_lo);
+	struct ghes *ghes = arg;
+	int err;
+
+	raw_spin_lock(&ghes_notify_lock_sse_lo);
+	err = __ghes_sse_callback(ghes, FIX_APEI_GHES_SSE_LOW_PRIORITY);
+	raw_spin_unlock(&ghes_notify_lock_sse_lo);
+
+	return err;
+}
+
+/* High priority */
+static int ghes_sse_hi_callback(u32 event_num, void *arg, struct pt_regs *regs)
+{
+	static DEFINE_RAW_SPINLOCK(ghes_notify_lock_sse_hi);
+	struct ghes *ghes = arg;
+	int err;
+
+	raw_spin_lock(&ghes_notify_lock_sse_hi);
+	err = __ghes_sse_callback(ghes, FIX_APEI_GHES_SSE_HIGH_PRIORITY);
+	raw_spin_unlock(&ghes_notify_lock_sse_hi);
+
+	return err;
+}
+
+static int apei_sse_register_ghes(struct ghes *ghes)
+{
+	return sse_register_ghes(ghes, ghes_sse_lo_callback,
+				 ghes_sse_hi_callback);
+}
+
+static int apei_sse_unregister_ghes(struct ghes *ghes)
+{
+	return sse_unregister_ghes(ghes);
+}
+#else /* CONFIG_ACPI_APEI_SSE */
+static int apei_sse_register_ghes(struct ghes *ghes) { return -ENOTSUPP; }
+static int apei_sse_unregister_ghes(struct ghes *ghes) { return -ENOTSUPP; }
+#endif
+
 static int ghes_probe(struct platform_device *ghes_dev)
 {
 	struct acpi_hest_generic *generic;
@@ -1576,6 +1640,15 @@ static int ghes_probe(struct platform_device *ghes_dev)
 		pr_warn(GHES_PFX "Generic hardware error source: %d notified via local interrupt is not supported!\n",
 			generic->header.source_id);
 		goto err;
+	case ACPI_HEST_NOTIFY_SSE:
+		if (!IS_ENABLED(CONFIG_ACPI_APEI_SSE)) {
+			pr_warn(GHES_PFX "Generic hardware error source: %d "
+				"notified via SSE is not supported\n",
+				generic->header.source_id);
+			rc = -ENOTSUPP;
+			goto err;
+		}
+		break;
 	default:
 		pr_warn(FW_WARN GHES_PFX "Unknown notification type: %u for generic hardware error source: %d\n",
 			generic->notify.type, generic->header.source_id);
@@ -1639,6 +1712,18 @@ static int ghes_probe(struct platform_device *ghes_dev)
 		if (rc)
 			goto err;
 		break;
+
+	case ACPI_HEST_NOTIFY_SSE:
+		rc = apei_sse_register_ghes(ghes);
+		if (rc) {
+			pr_err(GHES_PFX "Failed to register for SSE notification"
+			       " on vector %d\n",
+			       generic->notify.vector);
+			goto err;
+		}
+		pr_err(GHES_PFX "Registered SSE notification on vector %d\n",
+		       generic->notify.vector);
+		break;
 	default:
 		BUG();
 	}
@@ -1668,7 +1753,6 @@ static int ghes_probe(struct platform_device *ghes_dev)
 
 static void ghes_remove(struct platform_device *ghes_dev)
 {
-	int rc;
 	struct ghes *ghes;
 	struct acpi_hest_generic *generic;
 
@@ -1702,16 +1786,11 @@ static void ghes_remove(struct platform_device *ghes_dev)
 		ghes_nmi_remove(ghes);
 		break;
 	case ACPI_HEST_NOTIFY_SOFTWARE_DELEGATED:
-		rc = apei_sdei_unregister_ghes(ghes);
-		if (rc) {
-			/*
-			 * Returning early results in a resource leak, but we're
-			 * only here if stopping the hardware failed.
-			 */
-			dev_err(&ghes_dev->dev, "Failed to unregister ghes (%pe)\n",
-				ERR_PTR(rc));
-			return;
-		}
+		apei_sdei_unregister_ghes(ghes);
+		break;
+
+	case ACPI_HEST_NOTIFY_SSE:
+		apei_sse_unregister_ghes(ghes);
 		break;
 	default:
 		BUG();
-- 
2.43.0