feat(sme): enable SME2 functionality for NS world

FEAT_SME2 is an extension of FEAT_SME and an optional feature
from v9.2. Its an extension of SME, wherein it not only
processes matrix operations efficiently, but also provides
outer-product instructions to accelerate matrix operations.
It affords instructions for multi-vector operations.
Further, it adds an 512 bit architectural register ZT0.

This patch implements all the changes introduced with FEAT_SME2
to ensure that the instructions are allowed to access ZT0
register from Non-secure lower exception levels.

Additionally, it adds support to ensure FEAT_SME2 is aligned
with the existing FEATURE DETECTION mechanism, and documented.

Change-Id: Iee0f61943304a9cfc3db8f986047b1321d0a6463
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>

Makefile

@@ -861,8 +861,12 @@ ifeq ($(FEATURE_DETECTION),1)
     $(info FEATURE_DETECTION is an experimental feature)
 endif
 
-ifneq ($(ENABLE_SME_FOR_NS), 0)
-    $(info ENABLE_SME_FOR_NS is an experimental feature)
+ifneq ($(ENABLE_SME2_FOR_NS), 0)
+    ifeq (${ENABLE_SME_FOR_NS}, 0)
+        $(warning "ENABLE_SME2_FOR_NS requires ENABLE_SME_FOR_NS also to be set")
+        $(warning "Forced ENABLE_SME_FOR_NS=1")
+        override ENABLE_SME_FOR_NS	:= 1
+    endif
 endif
 
 ifeq (${ARM_XLAT_TABLES_LIB_V1}, 1)
@@ -884,6 +888,7 @@ ifeq (${ARCH},aarch32)
     ifneq (${ENABLE_SME_FOR_NS},0)
         $(error "ENABLE_SME_FOR_NS cannot be used with ARCH=aarch32")
     endif
+
     ifeq (${ENABLE_SVE_FOR_NS},1)
         # Warning instead of error due to CI dependency on this
         $(error "ENABLE_SVE_FOR_NS cannot be used with ARCH=aarch32")
@@ -925,6 +930,7 @@ ifeq (${CTX_INCLUDE_FPREGS},1)
     ifneq (${ENABLE_SME_FOR_NS},0)
         $(error "ENABLE_SME_FOR_NS cannot be used with CTX_INCLUDE_FPREGS")
     endif
+
     ifeq (${ENABLE_SVE_FOR_NS},1)
         # Warning instead of error due to CI dependency on this
         $(warning "ENABLE_SVE_FOR_NS cannot be used with CTX_INCLUDE_FPREGS")
@@ -1196,6 +1202,7 @@ $(eval $(call assert_numerics,\
         ENABLE_SPE_FOR_NS \
         ENABLE_SYS_REG_TRACE_FOR_NS \
         ENABLE_SME_FOR_NS \
+        ENABLE_SME2_FOR_NS \
         ENABLE_SVE_FOR_NS \
         ENABLE_TRF_FOR_NS \
         FW_ENC_STATUS \
@@ -1251,6 +1258,7 @@ $(eval $(call add_defines,\
         ENABLE_RME \
         ENABLE_RUNTIME_INSTRUMENTATION \
         ENABLE_SME_FOR_NS \
+        ENABLE_SME2_FOR_NS \
         ENABLE_SME_FOR_SWD \
         ENABLE_SPE_FOR_NS \
         ENABLE_SVE_FOR_NS \

changelog.yaml

@@ -128,7 +128,7 @@ subsections:
       - title: Trapping support for RNDR/RNDRRS (FEAT_RNG_TRAP)
         scope: rng-trap
 
-      - title: Scalable Matrix Extension (FEAT_SME)
+      - title: Scalable Matrix Extension (FEAT_SME, FEAT_SME2)
         scope: sme
 
       - title: Statistical profiling Extension (FEAT_SPE)

common/feat_detect.c

@@ -218,6 +218,8 @@ void detect_arch_features(void)
 	/* v9.2 features */
 	check_feature(ENABLE_SME_FOR_NS, read_feat_sme_id_field(),
 		      "SME", 1, 2);
+	check_feature(ENABLE_SME2_FOR_NS, read_feat_sme_id_field(),
+		      "SME2", 2, 2);
 
 	/* v9.4 features */
 	check_feature(ENABLE_FEAT_GCS, read_feat_gcs_id_field(), "GCS", 1, 1);

docs/getting_started/build-options.rst

@@ -442,6 +442,13 @@ Common build options
    build with these options will fail. This flag can take the values 0 to 2, to
    align with the ``FEATURE_DETECTION`` mechanism. Default is 0.
 
+-  ``ENABLE_SME2_FOR_NS``: Numeric value to enable Scalable Matrix Extension
+   version 2 (SME2) for the non-secure world only. SME2 is an optional
+   architectural feature for AArch64 and TF-A support is experimental.
+   This should be set along with ENABLE_SME_FOR_NS=1, if not, the default SME
+   accesses will still be trapped. This flag can take the values 0 to 2, to
+   align with the ``FEATURE_DETECTION`` mechanism. Default is 0.
+
 -  ``ENABLE_SME_FOR_SWD``: Boolean option to enable the Scalable Matrix
    Extension for secure world use along with SVE and FPU/SIMD, ENABLE_SME_FOR_NS
    must also be set to use this. If enabling this, the secure world MUST

include/arch/aarch64/arch.h

@@ -412,6 +412,7 @@
 #define ID_AA64PFR1_EL1_SME_MASK		ULL(0xf)
 #define ID_AA64PFR1_EL1_SME_NOT_SUPPORTED	ULL(0x0)
 #define ID_AA64PFR1_EL1_SME_SUPPORTED		ULL(0x1)
+#define ID_AA64PFR1_EL1_SME2_SUPPORTED		ULL(0x2)
 
 /* ID_PFR1_EL1 definitions */
 #define ID_PFR1_VIRTEXT_SHIFT	U(12)
@@ -519,6 +520,8 @@
 #define CPACR_EL1_FP_TRAP_EL0	UL(0x1)
 #define CPACR_EL1_FP_TRAP_ALL	UL(0x2)
 #define CPACR_EL1_FP_TRAP_NONE	UL(0x3)
+#define CPACR_EL1_SMEN_SHIFT	U(24)
+#define CPACR_EL1_SMEN_MASK	ULL(0x3)
 
 /* SCR definitions */
 #define SCR_RES1_BITS		((U(1) << 4) | (U(1) << 5))
@@ -1026,11 +1029,16 @@
 #define ID_AA64SMFR0_EL1_SME_FA64_SHIFT		U(63)
 #define ID_AA64SMFR0_EL1_SME_FA64_MASK		U(0x1)
 #define ID_AA64SMFR0_EL1_SME_FA64_SUPPORTED	U(0x1)
+#define ID_AA64SMFR0_EL1_SME_VER_SHIFT		U(55)
+#define ID_AA64SMFR0_EL1_SME_VER_MASK		ULL(0xf)
+#define ID_AA64SMFR0_EL1_SME_INST_SUPPORTED	ULL(0x0)
+#define ID_AA64SMFR0_EL1_SME2_INST_SUPPORTED	ULL(0x1)
 
 /* SMCR_ELx definitions */
 #define SMCR_ELX_LEN_SHIFT		U(0)
-#define SMCR_ELX_LEN_MASK		U(0x1ff)
+#define SMCR_ELX_LEN_MAX		U(0x1ff)
 #define SMCR_ELX_FA64_BIT		(U(1) << 31)
+#define SMCR_ELX_EZT0_BIT		(U(1) << 30)
 
 /*******************************************************************************
  * Definitions of MAIR encodings for device and normal memory

include/arch/aarch64/arch_features.h

@@ -657,4 +657,17 @@ static inline bool is_feat_sme_supported(void)
 	return read_feat_sme_id_field() >= ID_AA64PFR1_EL1_SME_SUPPORTED;
 }
 
+static inline bool is_feat_sme2_supported(void)
+{
+	if (ENABLE_SME2_FOR_NS == FEAT_STATE_DISABLED) {
+		return false;
+	}
+
+	if (ENABLE_SME2_FOR_NS == FEAT_STATE_ALWAYS) {
+		return true;
+	}
+
+	return read_feat_sme_id_field() >= ID_AA64PFR1_EL1_SME2_SUPPORTED;
+}
+
 #endif /* ARCH_FEATURES_H */

lib/extensions/sme/sme.c

@@ -43,11 +43,23 @@ void sme_enable(cpu_context_t *context)
 	 * to be the least restrictive, then lower ELs can restrict as needed
 	 * using SMCR_EL2 and SMCR_EL1.
 	 */
-	reg = SMCR_ELX_LEN_MASK;
+	reg = SMCR_ELX_LEN_MAX;
+
 	if (read_feat_sme_fa64_id_field() != 0U) {
 		VERBOSE("[SME] FA64 enabled\n");
 		reg |= SMCR_ELX_FA64_BIT;
 	}
+
+	/*
+	 * Enable access to ZT0 register.
+	 * Make sure FEAT_SME2 is supported by the hardware before continuing.
+	 * If supported, Set the EZT0 bit in SMCR_EL3 to allow instructions to
+	 * access ZT0 register without trapping.
+	 */
+	if (is_feat_sme2_supported()) {
+		VERBOSE("SME2 enabled\n");
+		reg |= SMCR_ELX_EZT0_BIT;
+	}
 	write_smcr_el3(reg);
 
 	/* Reset CPTR_EL3 value. */

make_helpers/defaults.mk

@@ -405,6 +405,9 @@ ifneq (${ENABLE_SME_FOR_NS},0)
 	override ENABLE_SVE_FOR_SWD	:= 0
 endif
 
+# SME2 defaults to disabled
+ENABLE_SME2_FOR_NS		:= 0
+
 SANITIZE_UB := off
 
 # For ARMv8.1 (AArch64) platforms, enabling this option selects the spinlock

plat/arm/board/fvp/platform.mk

@@ -55,6 +55,7 @@ ifeq (${SPM_MM}, 0)
 ifeq (${ENABLE_RME}, 0)
 ifeq (${CTX_INCLUDE_FPREGS}, 0)
 	ENABLE_SME_FOR_NS		:= 2
+	ENABLE_SME2_FOR_NS		:= 2
 endif
 endif
 endif