AArch64: Enable MPAM for lower ELs

Memory Partitioning And Monitoring is an Armv8.4 feature that enables
various memory system components and resources to define partitions.
Software running at various ELs can then assign themselves to the
desired partition to control their performance aspects.

With this patch, when ENABLE_MPAM_FOR_LOWER_ELS is set to 1, EL3 allows
lower ELs to access their own MPAM registers without trapping to EL3.
This patch however doesn't make use of partitioning in EL3; platform
initialisation code should configure and use partitions in EL3 if
required.

Change-Id: I5a55b6771ccaa0c1cffc05543d2116b60cbbcdcd
Co-authored-by: James Morse <james.morse@arm.com>
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

Makefile

@@ -550,6 +550,7 @@ $(eval $(call assert_boolean,DYN_DISABLE_AUTH))
 $(eval $(call assert_boolean,EL3_EXCEPTION_HANDLING))
 $(eval $(call assert_boolean,ENABLE_AMU))
 $(eval $(call assert_boolean,ENABLE_ASSERTIONS))
+$(eval $(call assert_boolean,ENABLE_MPAM_FOR_LOWER_ELS))
 $(eval $(call assert_boolean,ENABLE_PLAT_COMPAT))
 $(eval $(call assert_boolean,ENABLE_PMF))
 $(eval $(call assert_boolean,ENABLE_PSCI_STAT))
@@ -601,6 +602,7 @@ $(eval $(call add_define,CTX_INCLUDE_FPREGS))
 $(eval $(call add_define,EL3_EXCEPTION_HANDLING))
 $(eval $(call add_define,ENABLE_AMU))
 $(eval $(call add_define,ENABLE_ASSERTIONS))
+$(eval $(call add_define,ENABLE_MPAM_FOR_LOWER_ELS))
 $(eval $(call add_define,ENABLE_PLAT_COMPAT))
 $(eval $(call add_define,ENABLE_PMF))
 $(eval $(call add_define,ENABLE_PSCI_STAT))

bl31/bl31.mk

@@ -63,6 +63,10 @@ ifeq (${ENABLE_SVE_FOR_NS},1)
 BL31_SOURCES		+=	lib/extensions/sve/sve.c
 endif
 
+ifeq (${ENABLE_MPAM_FOR_LOWER_ELS},1)
+BL31_SOURCES		+=	lib/extensions/mpam/mpam.c
+endif
+
 ifeq (${WORKAROUND_CVE_2017_5715},1)
 BL31_SOURCES		+=	lib/cpus/aarch64/wa_cve_2017_5715_bpiall.S	\
 				lib/cpus/aarch64/wa_cve_2017_5715_mmu.S

docs/user-guide.rst

@@ -350,6 +350,17 @@ Common build options
    that is only required for the assertion and does not fit in the assertion
    itself.
 
+-  ``ENABLE_MPAM_FOR_LOWER_ELS``: Boolean option to enable lower ELs to use MPAM
+   feature. MPAM is an optional Armv8.4 extension that enables various memory
+   system components and resources to define partitions; software running at
+   various ELs can assign themselves to desired partition to control their
+   performance aspects.
+
+   When this option is set to ``1``, EL3 allows lower ELs to access their own
+   MPAM registers without trapping into EL3. This option doesn't make use of
+   partitioning in EL3, however. Platform initialisation code should configure
+   and use partitions in EL3 as required. This option defaults to ``0``.
+
 -  ``ENABLE_PMF``: Boolean option to enable support for optional Performance
    Measurement Framework(PMF). Default is 0.
 

include/lib/aarch64/arch.h

@@ -117,6 +117,8 @@
 #define ID_AA64PFR0_SVE_SHIFT	U(32)
 #define ID_AA64PFR0_SVE_MASK	ULL(0xf)
 #define ID_AA64PFR0_SVE_LENGTH	U(4)
+#define ID_AA64PFR0_MPAM_SHIFT	U(40)
+#define ID_AA64PFR0_MPAM_MASK	ULL(0xf)
 #define ID_AA64PFR0_CSV2_SHIFT	U(56)
 #define ID_AA64PFR0_CSV2_MASK	ULL(0xf)
 #define ID_AA64PFR0_CSV2_LENGTH	U(4)
@@ -657,6 +659,14 @@
  ******************************************************************************/
 #define PMBLIMITR_EL1		S3_0_C9_C10_0
 
+/*******************************************************************************
+ * Definitions for system register interface to MPAM
+ ******************************************************************************/
+#define MPAMIDR_EL1		S3_0_C10_C4_4
+#define MPAM2_EL2		S3_4_C10_C5_0
+#define MPAMHCR_EL2		S3_4_C10_C4_0
+#define MPAM3_EL3		S3_6_C10_C5_0
+
 /*******************************************************************************
  * Definitions for system register interface to AMU for ARMv8.4 onwards
  ******************************************************************************/
@@ -722,6 +732,11 @@
 #define AMCGCR_EL0_CG1NC_LENGTH	U(8)
 #define AMCGCR_EL0_CG1NC_MASK	U(0xff)
 
+/* MPAM register definitions */
+#define MPAM3_EL3_MPAMEN_BIT		(ULL(1) << 63)
+
+#define MPAMIDR_HAS_HCR_BIT		(ULL(1) << 17)
+
 /*******************************************************************************
  * RAS system registers
  *******************************************************************************/

include/lib/aarch64/arch_helpers.h

@@ -328,6 +328,11 @@ DEFINE_RENAME_SYSREG_RW_FUNCS(amcntenset0_el0, AMCNTENSET0_EL0)
 DEFINE_RENAME_SYSREG_RW_FUNCS(amcntenclr1_el0, AMCNTENCLR1_EL0)
 DEFINE_RENAME_SYSREG_RW_FUNCS(amcntenset1_el0, AMCNTENSET1_EL0)
 
+DEFINE_RENAME_SYSREG_READ_FUNC(mpamidr_el1, MPAMIDR_EL1)
+DEFINE_RENAME_SYSREG_RW_FUNCS(mpam3_el3, MPAM3_EL3)
+DEFINE_RENAME_SYSREG_RW_FUNCS(mpam2_el2, MPAM2_EL2)
+DEFINE_RENAME_SYSREG_RW_FUNCS(mpamhcr_el2, MPAMHCR_EL2)
+
 DEFINE_RENAME_SYSREG_RW_FUNCS(pmblimitr_el1, PMBLIMITR_EL1)
 
 DEFINE_RENAME_SYSREG_WRITE_FUNC(zcr_el3, ZCR_EL3)

include/lib/extensions/mpam.h

+/*
+ * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef MPAM_H
+#define MPAM_H
+
+#include <stdbool.h>
+
+bool mpam_supported(void);
+void mpam_enable(int el2_unused);
+
+#endif /* MPAM_H */

lib/el3_runtime/aarch64/context_mgmt.c

@@ -12,6 +12,7 @@
 #include <context.h>
 #include <context_mgmt.h>
 #include <interrupt_mgmt.h>
+#include <mpam.h>
 #include <platform.h>
 #include <platform_def.h>
 #include <pubsub_events.h>
@@ -244,6 +245,10 @@ static void enable_extensions_nonsecure(int el2_unused)
 #if ENABLE_SVE_FOR_NS
 	sve_enable(el2_unused);
 #endif
+
+#if ENABLE_MPAM_FOR_LOWER_ELS
+	mpam_enable(el2_unused);
+#endif
 #endif
 }
 

lib/extensions/mpam/mpam.c

+/*
+ * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch.h>
+#include <arch_helpers.h>
+#include <mpam.h>
+#include <stdbool.h>
+
+bool mpam_supported(void)
+{
+	uint64_t features = read_id_aa64dfr0_el1() >> ID_AA64PFR0_MPAM_SHIFT;
+
+	return ((features & ID_AA64PFR0_MPAM_MASK) != 0U);
+}
+
+void mpam_enable(int el2_unused)
+{
+	if (!mpam_supported())
+		return;
+
+	/*
+	 * Enable MPAM, and disable trapping to EL3 when lower ELs access their
+	 * own MPAM registers.
+	 */
+	write_mpam3_el3(MPAM3_EL3_MPAMEN_BIT);
+
+	/*
+	 * If EL2 is implemented but unused, disable trapping to EL2 when lower
+	 * ELs access their own MPAM registers.
+	 */
+	if (el2_unused != 0) {
+		write_mpam2_el2(0);
+
+		if ((read_mpamidr_el1() & MPAMIDR_HAS_HCR_BIT) != 0U)
+			write_mpamhcr_el2(0);
+	}
+}

make_helpers/defaults.mk

@@ -62,6 +62,9 @@ DEFAULT_PLAT			:= fvp
 # development platforms.
 DYN_DISABLE_AUTH		:= 0
 
+# Build option to enable MPAM for lower ELs
+ENABLE_MPAM_FOR_LOWER_ELS	:= 0
+
 # Flag to enable Performance Measurement Framework
 ENABLE_PMF			:= 0