fix(gic600): workaround for Part 1 of GIC600 erratum 2384374

GIC600 erratum 2384374 is a Category B erratum. Part 1 is fixed
in this patch, and the Part 1 failure mode is described as
'If the packet to be sent is a SET packet, then a higher priority SET
may not be sent when it should be until an unblocking event occurs.'

This is handled by calling gicv3_apply_errata_wa_2384374() in the
ehf_deactivate_priority() path, so that when EHF restores the priority
to the original priority, the interrupt packet buffered
in the GIC can be sent.

gicv3_apply_errata_wa_2384374() is the workaround for
the Part 2 of erratum 2384374 which flush packets from the GIC buffer
and is being used in this patch.

SDEN can be found here:
https://developer.arm.com/documentation/sden892601/latest/

Signed-off-by: Arvind Ram Prakash <arvind.ramprakash@arm.com>
Change-Id: I4bb6dcf86c94125cbc574e0dc5119abe43e84731

bl31/ehf.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2023, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2024, Arm Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -203,10 +203,20 @@ void ehf_deactivate_priority(unsigned int priority)
 	 * one stashed earlier if there are no more to deactivate.
 	 */
 	cur_pri_idx = get_pe_highest_active_idx(pe_data);
-	if (cur_pri_idx == EHF_INVALID_IDX)
+
+#if GIC600_ERRATA_WA_2384374
+	if (cur_pri_idx == EHF_INVALID_IDX) {
+		old_mask = plat_ic_deactivate_priority(pe_data->init_pri_mask);
+	} else {
+		old_mask = plat_ic_deactivate_priority(priority);
+	}
+#else
+	if (cur_pri_idx == EHF_INVALID_IDX) {
 		old_mask = plat_ic_set_priority_mask(pe_data->init_pri_mask);
-	else
+	} else {
 		old_mask = plat_ic_set_priority_mask(priority);
+	}
+#endif
 
 	if (old_mask > priority) {
 		ERROR("Deactivation priority (0x%x) lower than Priority Mask (0x%x)\n",

docs/components/platform-interrupt-controller-API.rst

@@ -282,9 +282,28 @@ may be signalled to the PE. The API should return the current priority value
 that it's overwriting.
 
 In case of Arm standard platforms using GIC, the implementation of the API
-inserts to order memory updates before updating mask, then writes to the GIC
-*Priority Mask Register*, and make sure memory updates are visible before
-potential trigger due to mask update.
+inserts barriers to order memory updates before updating mask,
+then writes to the GIC *Priority Mask Register*, and make sure memory updates
+are visible before potential trigger due to mask update.
+
+Function: unsigned int plat_ic_deactivate_priority(unsigned int id); [optional]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+    Argument : unsigned int
+    Return   : int
+
+This API performs the operations of plat_ic_set_priority_mask along with
+calling the errata workaround gicv3_apply_errata_wa_2384374(). This is
+performed when priority mask is restored to it's older value. This API returns
+the current priority value that it's overwriting.
+
+In case of Arm standard platforms using GIC, the implementation of the API
+inserts barriers to order memory updates before updating mask, then writes
+to the GIC *Priority Mask Register*, and make sure memory updates
+are visible before potential trigger due to mask update, and
+applies 2384374 GIC errata workaround to process pending interrupt packets.
 
 .. _plat_ic_get_interrupt_id:
 

drivers/arm/gic/v3/gicv3_main.c

@@ -1320,6 +1320,31 @@ unsigned int gicv3_set_pmr(unsigned int mask)
 	return old_mask;
 }
 
+/*******************************************************************************
+ * This function restores the PMR register to old value and also triggers
+ * gicv3_apply_errata_wa_2384374() that flushes the GIC buffer allowing any
+ * pending interrupts to processed. Returns the original PMR.
+ ******************************************************************************/
+unsigned int gicv3_deactivate_priority(unsigned int mask)
+{
+
+	unsigned int old_mask, proc_num;
+	uintptr_t gicr_base;
+
+	old_mask = gicv3_set_pmr(mask);
+
+	proc_num = plat_my_core_pos();
+	gicr_base = gicv3_driver_data->rdistif_base_addrs[proc_num];
+	assert(gicr_base != 0UL);
+
+	/* Add DSB to ensure visibility of System register writes */
+	dsb();
+
+	gicv3_apply_errata_wa_2384374(gicr_base);
+
+	return old_mask;
+}
+
 /*******************************************************************************
  * This function delegates the responsibility of discovering the corresponding
  * Redistributor frames to each CPU itself. It is a modified version of

include/drivers/arm/gicv3.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2023, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2024, Arm Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -588,6 +588,7 @@ void gicv3_set_spi_routing(unsigned int id, unsigned int irm,
 void gicv3_set_interrupt_pending(unsigned int id, unsigned int proc_num);
 void gicv3_clear_interrupt_pending(unsigned int id, unsigned int proc_num);
 unsigned int gicv3_set_pmr(unsigned int mask);
+unsigned int gicv3_deactivate_priority(unsigned int mask);
 
 void gicv3_get_component_prodid_rev(const uintptr_t gicd_base,
 				    unsigned int *gic_prod_id,

include/plat/common/platform.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013-2023, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2024, Arm Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -136,6 +136,7 @@ void plat_ic_set_spi_routing(unsigned int id, unsigned int routing_mode,
 void plat_ic_set_interrupt_pending(unsigned int id);
 void plat_ic_clear_interrupt_pending(unsigned int id);
 unsigned int plat_ic_set_priority_mask(unsigned int mask);
+unsigned int plat_ic_deactivate_priority(unsigned int mask);
 unsigned int plat_ic_get_interrupt_id(unsigned int raw);
 
 /*******************************************************************************

plat/common/plat_gicv3.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2023, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2024, Arm Limited and Contributors. All rights reserved.
  * Portions copyright (c) 2021-2022, ProvenRun S.A.S. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
@@ -344,6 +344,11 @@ unsigned int plat_ic_set_priority_mask(unsigned int mask)
 	return gicv3_set_pmr(mask);
 }
 
+unsigned int plat_ic_deactivate_priority(unsigned int mask)
+{
+	return gicv3_deactivate_priority(mask);
+}
+
 unsigned int plat_ic_get_interrupt_id(unsigned int raw)
 {
 	unsigned int id = raw & INT_ID_MASK;