Merge "refactor(twed): improve TWED enablement in EL-3" into integration
diff --git a/Makefile b/Makefile
index 3a8a522..851c944 100644
--- a/Makefile
+++ b/Makefile
@@ -1068,6 +1068,8 @@
NR_OF_FW_BANKS \
NR_OF_IMAGES_IN_FW_BANK \
RAS_EXTENSION \
+ TWED_DELAY \
+ ENABLE_FEAT_TWED \
)))
ifdef KEY_SIZE
@@ -1184,6 +1186,8 @@
ENABLE_FEAT_CSV2_2 \
ENABLE_FEAT_PAN \
FEATURE_DETECTION \
+ TWED_DELAY \
+ ENABLE_FEAT_TWED \
)))
ifeq (${SANITIZE_UB},trap)
diff --git a/common/feat_detect.c b/common/feat_detect.c
index ef09b86..8f98876 100644
--- a/common/feat_detect.c
+++ b/common/feat_detect.c
@@ -203,6 +203,16 @@
#endif
}
+/***********************************************************
+ * Feature : FEAT_TWED (Delayed Trapping of WFE Instruction)
+ **********************************************************/
+static void read_feat_twed(void)
+{
+#if (ENABLE_FEAT_TWED == FEAT_STATE_1)
+ feat_detect_panic(is_armv8_6_twed_present(), "TWED");
+#endif
+}
+
/******************************************************************
* Feature : FEAT_HCX (Extended Hypervisor Configuration Register)
*****************************************************************/
@@ -279,6 +289,7 @@
read_feat_amuv1p1();
read_feat_fgt();
read_feat_ecv();
+ read_feat_twed();
/* v8.7 features */
read_feat_hcx();
diff --git a/docs/getting_started/build-options.rst b/docs/getting_started/build-options.rst
index d30e22f..3a67b0f 100644
--- a/docs/getting_started/build-options.rst
+++ b/docs/getting_started/build-options.rst
@@ -327,6 +327,14 @@
This flag can take values 0 to 2, to align with the ``FEATURE_DETECTION``
mechanism. Default is ``0``.
+- ``ENABLE_FEAT_TWED``: Numeric value to enable the ``FEAT_TWED`` (Delayed
+ trapping of WFE Instruction) extension. ``FEAT_TWED`` is a optional feature
+ available on Arm v8.6. This flag can take values 0 to 2, to align with the
+ ``FEATURE_DETECTION`` mechanism. Default is ``0``.
+
+ When ``ENABLE_FEAT_TWED`` is set to ``1``, WFE instruction trapping gets
+ delayed by the amount of value in ``TWED_DELAY``.
+
- ``ENABLE_FEAT_VHE``: Numeric value to enable the ``FEAT_VHE`` (Virtualization
Host Extensions) extension. It allows access to CONTEXTIDR_EL2 register
during EL2 context save/restore operations.``FEAT_VHE`` is a mandatory
@@ -845,6 +853,12 @@
When ``EL3_EXCEPTION_HANDLING`` is ``1``, ``TSP_NS_INTR_ASYNC_PREEMPT``
must also be set to ``1``.
+- ``TWED_DELAY``: Numeric value to be set in order to delay the trapping of
+ WFE instruction. ``ENABLE_FEAT_TWED`` build option must be enabled to set
+ this delay. It can take values in the range (0-15). Default value is ``0``
+ and based on this value, 2^(TWED_DELAY + 8) cycles will be delayed.
+ Platforms need to explicitly update this value based on their requirements.
+
- ``USE_ARM_LINK``: This flag determines whether to enable support for ARM
linker. When the ``LINKER`` build variable points to the armlink linker,
this flag is enabled automatically. To enable support for armlink, platforms
diff --git a/docs/getting_started/porting-guide.rst b/docs/getting_started/porting-guide.rst
index 3d3b2e3..2c6a005 100644
--- a/docs/getting_started/porting-guide.rst
+++ b/docs/getting_started/porting-guide.rst
@@ -2118,21 +2118,6 @@
of the system counter, which is retrieved from the first entry in the frequency
modes table.
-Function : plat_arm_set_twedel_scr_el3() [optional]
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-::
-
- Argument : void
- Return : uint32_t
-
-This function is used in v8.6+ systems to set the WFE trap delay value in
-SCR_EL3. If this function returns TWED_DISABLED or is left unimplemented, this
-feature is not enabled. The only hook provided is to set the TWED fields in
-SCR_EL3, there are similar fields in HCR_EL2, SCTLR_EL2, and SCTLR_EL1 to adjust
-the WFE trap delays in lower ELs and these fields should be set by the
-appropriate EL2 or EL1 code depending on the platform configuration.
-
#define : PLAT_PERCPU_BAKERY_LOCK_SIZE [optional]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/include/lib/extensions/twed.h b/include/lib/extensions/twed.h
deleted file mode 100644
index eac4aa3..0000000
--- a/include/lib/extensions/twed.h
+++ /dev/null
@@ -1,16 +0,0 @@
-/*
- * Copyright (c) 2020, Arm Limited. All rights reserved.
- *
- * SPDX-License-Identifier: BSD-3-Clause
- */
-
-#ifndef TWED_H
-#define TWED_H
-
-#include <stdint.h>
-
-#define TWED_DISABLED U(0xFFFFFFFF)
-
-uint32_t plat_arm_set_twedel_scr_el3(void);
-
-#endif /* TWEDE_H */
diff --git a/lib/el3_runtime/aarch64/context_mgmt.c b/lib/el3_runtime/aarch64/context_mgmt.c
index 459ca2c..47e7d8c 100644
--- a/lib/el3_runtime/aarch64/context_mgmt.c
+++ b/lib/el3_runtime/aarch64/context_mgmt.c
@@ -27,11 +27,14 @@
#include <lib/extensions/sys_reg_trace.h>
#include <lib/extensions/trbe.h>
#include <lib/extensions/trf.h>
-#include <lib/extensions/twed.h>
#include <lib/utils.h>
-static void manage_extensions_secure(cpu_context_t *ctx);
+#if ENABLE_FEAT_TWED
+/* Make sure delay value fits within the range(0-15) */
+CASSERT(((TWED_DELAY & ~SCR_TWEDEL_MASK) == 0U), assert_twed_delay_value_check);
+#endif /* ENABLE_FEAT_TWED */
+static void manage_extensions_secure(cpu_context_t *ctx);
/******************************************************************************
* This function performs initializations that are specific to SECURE state
* and updates the cpu context specified by 'ctx'.
@@ -329,23 +332,16 @@
sctlr_elx |= SCTLR_IESB_BIT;
#endif
+#if ENABLE_FEAT_TWED
/* Enable WFE trap delay in SCR_EL3 if supported and configured */
- if (is_armv8_6_twed_present()) {
- uint32_t delay = plat_arm_set_twedel_scr_el3();
-
- if (delay != TWED_DISABLED) {
- /* Make sure delay value fits */
- assert((delay & ~SCR_TWEDEL_MASK) == 0U);
+ /* Set delay in SCR_EL3 */
+ scr_el3 &= ~(SCR_TWEDEL_MASK << SCR_TWEDEL_SHIFT);
+ scr_el3 |= ((TWED_DELAY & SCR_TWEDEL_MASK)
+ << SCR_TWEDEL_SHIFT);
- /* Set delay in SCR_EL3 */
- scr_el3 &= ~(SCR_TWEDEL_MASK << SCR_TWEDEL_SHIFT);
- scr_el3 |= ((delay & SCR_TWEDEL_MASK)
- << SCR_TWEDEL_SHIFT);
-
- /* Enable WFE delay */
- scr_el3 |= SCR_TWEDEn_BIT;
- }
- }
+ /* Enable WFE delay */
+ scr_el3 |= SCR_TWEDEn_BIT;
+#endif /* ENABLE_FEAT_TWED */
/*
* Store the initialised SCTLR_EL1 value in the cpu_context - SCTLR_EL2
diff --git a/make_helpers/defaults.mk b/make_helpers/defaults.mk
index 7b66569..bf8771d 100644
--- a/make_helpers/defaults.mk
+++ b/make_helpers/defaults.mk
@@ -169,6 +169,9 @@
# Flag to enable Virtualization Host Extensions
ENABLE_FEAT_VHE := 0
+# Flag to enable delayed trapping of WFE instruction (FEAT_TWED)
+ENABLE_FEAT_TWED := 0
+
# By default BL31 encryption disabled
ENCRYPT_BL31 := 0
@@ -443,3 +446,9 @@
# lower ELs, i.e. NS-EL2, or NS-EL1 if NS-EL2 implemented but unused
# if FEAT_TRF is implemented.
ENABLE_TRF_FOR_NS := 0
+
+# In v8.6+ platforms with delayed trapping of WFE being supported
+# via FEAT_TWED, this flag takes the delay value to be set in the
+# SCR_EL3.TWEDEL(4bit) field, when FEAT_TWED is implemented.
+# By default it takes 0, and need to be updated by the platforms.
+TWED_DELAY := 0
diff --git a/plat/common/aarch64/plat_common.c b/plat/common/aarch64/plat_common.c
index 38a5786..e807660 100644
--- a/plat/common/aarch64/plat_common.c
+++ b/plat/common/aarch64/plat_common.c
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2014-2020, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2014-2022, ARM Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
@@ -13,7 +13,6 @@
#if RAS_EXTENSION
#include <lib/extensions/ras.h>
#endif
-#include <lib/extensions/twed.h>
#include <lib/xlat_tables/xlat_mmu_helpers.h>
#include <plat/common/platform.h>
@@ -23,7 +22,6 @@
* platforms but may also be overridden by a platform if required.
*/
#pragma weak bl31_plat_runtime_setup
-#pragma weak plat_arm_set_twedel_scr_el3
#if SDEI_SUPPORT
#pragma weak plat_sdei_handle_masked_trigger
@@ -105,16 +103,3 @@
#endif
panic();
}
-
-/*******************************************************************************
- * In v8.6+ platforms with delayed trapping of WFE this hook sets the delay. It
- * is a weak function definition so can be overridden depending on the
- * requirements of a platform. The only hook provided is for the TWED fields
- * in SCR_EL3, the TWED fields in HCR_EL2, SCTLR_EL2, and SCTLR_EL1 should be
- * configured as needed in lower exception levels.
- ******************************************************************************/
-
-uint32_t plat_arm_set_twedel_scr_el3(void)
-{
- return TWED_DISABLED;
-}