arm64: Introduce ID_ISAR6 CPU register

This adds basic building blocks required for ID_ISAR6 CPU register which
identifies support for various instruction implementation on AArch32 state.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-kernel@vger.kernel.org
Cc: kvmarm@lists.cs.columbia.edu
Acked-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
[will: Ensure SPECRES is treated the same as on A64]
Signed-off-by: Will Deacon <will@kernel.org>

arch/arm64/include/asm/cpu.h

@@ -39,6 +39,7 @@ struct cpuinfo_arm64 {
 	u32		reg_id_isar3;
 	u32		reg_id_isar4;
 	u32		reg_id_isar5;
+	u32		reg_id_isar6;
 	u32		reg_id_mmfr0;
 	u32		reg_id_mmfr1;
 	u32		reg_id_mmfr2;

arch/arm64/include/asm/sysreg.h

@@ -146,6 +146,7 @@
 #define SYS_ID_ISAR4_EL1		sys_reg(3, 0, 0, 2, 4)
 #define SYS_ID_ISAR5_EL1		sys_reg(3, 0, 0, 2, 5)
 #define SYS_ID_MMFR4_EL1		sys_reg(3, 0, 0, 2, 6)
+#define SYS_ID_ISAR6_EL1		sys_reg(3, 0, 0, 2, 7)
 
 #define SYS_MVFR0_EL1			sys_reg(3, 0, 0, 3, 0)
 #define SYS_MVFR1_EL1			sys_reg(3, 0, 0, 3, 1)
@@ -691,6 +692,14 @@
 #define ID_ISAR5_AES_SHIFT		4
 #define ID_ISAR5_SEVL_SHIFT		0
 
+#define ID_ISAR6_I8MM_SHIFT		24
+#define ID_ISAR6_BF16_SHIFT		20
+#define ID_ISAR6_SPECRES_SHIFT		16
+#define ID_ISAR6_SB_SHIFT		12
+#define ID_ISAR6_FHM_SHIFT		8
+#define ID_ISAR6_DP_SHIFT		4
+#define ID_ISAR6_JSCVT_SHIFT		0
+
 #define MVFR0_FPROUND_SHIFT		28
 #define MVFR0_FPSHVEC_SHIFT		24
 #define MVFR0_FPSQRT_SHIFT		20

arch/arm64/kernel/cpufeature.c

@@ -325,6 +325,17 @@ static const struct arm64_ftr_bits ftr_id_mmfr4[] = {
 	ARM64_FTR_END,
 };
 
+static const struct arm64_ftr_bits ftr_id_isar6[] = {
+	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR6_I8MM_SHIFT, 4, 0),
+	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR6_BF16_SHIFT, 4, 0),
+	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR6_SPECRES_SHIFT, 4, 0),
+	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR6_SB_SHIFT, 4, 0),
+	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR6_FHM_SHIFT, 4, 0),
+	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR6_DP_SHIFT, 4, 0),
+	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR6_JSCVT_SHIFT, 4, 0),
+	ARM64_FTR_END,
+};
+
 static const struct arm64_ftr_bits ftr_id_pfr0[] = {
 	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 12, 4, 0),		/* State3 */
 	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 8, 4, 0),		/* State2 */
@@ -408,6 +419,7 @@ static const struct __ftr_reg_entry {
 	ARM64_FTR_REG(SYS_ID_ISAR4_EL1, ftr_generic_32bits),
 	ARM64_FTR_REG(SYS_ID_ISAR5_EL1, ftr_id_isar5),
 	ARM64_FTR_REG(SYS_ID_MMFR4_EL1, ftr_id_mmfr4),
+	ARM64_FTR_REG(SYS_ID_ISAR6_EL1, ftr_id_isar6),
 
 	/* Op1 = 0, CRn = 0, CRm = 3 */
 	ARM64_FTR_REG(SYS_MVFR0_EL1, ftr_generic_32bits),
@@ -612,6 +624,7 @@ void __init init_cpu_features(struct cpuinfo_arm64 *info)
 		init_cpu_ftr_reg(SYS_ID_ISAR3_EL1, info->reg_id_isar3);
 		init_cpu_ftr_reg(SYS_ID_ISAR4_EL1, info->reg_id_isar4);
 		init_cpu_ftr_reg(SYS_ID_ISAR5_EL1, info->reg_id_isar5);
+		init_cpu_ftr_reg(SYS_ID_ISAR6_EL1, info->reg_id_isar6);
 		init_cpu_ftr_reg(SYS_ID_MMFR0_EL1, info->reg_id_mmfr0);
 		init_cpu_ftr_reg(SYS_ID_MMFR1_EL1, info->reg_id_mmfr1);
 		init_cpu_ftr_reg(SYS_ID_MMFR2_EL1, info->reg_id_mmfr2);
@@ -765,6 +778,8 @@ void update_cpu_features(int cpu,
 					info->reg_id_isar4, boot->reg_id_isar4);
 		taint |= check_update_ftr_reg(SYS_ID_ISAR5_EL1, cpu,
 					info->reg_id_isar5, boot->reg_id_isar5);
+		taint |= check_update_ftr_reg(SYS_ID_ISAR6_EL1, cpu,
+					info->reg_id_isar6, boot->reg_id_isar6);
 
 		/*
 		 * Regardless of the value of the AuxReg field, the AIFSR, ADFSR, and
@@ -843,6 +858,7 @@ static u64 __read_sysreg_by_encoding(u32 sys_id)
 	read_sysreg_case(SYS_ID_ISAR3_EL1);
 	read_sysreg_case(SYS_ID_ISAR4_EL1);
 	read_sysreg_case(SYS_ID_ISAR5_EL1);
+	read_sysreg_case(SYS_ID_ISAR6_EL1);
 	read_sysreg_case(SYS_MVFR0_EL1);
 	read_sysreg_case(SYS_MVFR1_EL1);
 	read_sysreg_case(SYS_MVFR2_EL1);

arch/arm64/kernel/cpuinfo.c

@@ -367,6 +367,7 @@ static void __cpuinfo_store_cpu(struct cpuinfo_arm64 *info)
 		info->reg_id_isar3 = read_cpuid(ID_ISAR3_EL1);
 		info->reg_id_isar4 = read_cpuid(ID_ISAR4_EL1);
 		info->reg_id_isar5 = read_cpuid(ID_ISAR5_EL1);
+		info->reg_id_isar6 = read_cpuid(ID_ISAR6_EL1);
 		info->reg_id_mmfr0 = read_cpuid(ID_MMFR0_EL1);
 		info->reg_id_mmfr1 = read_cpuid(ID_MMFR1_EL1);
 		info->reg_id_mmfr2 = read_cpuid(ID_MMFR2_EL1);

arch/arm64/kvm/sys_regs.c

@@ -1424,7 +1424,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 	ID_SANITISED(ID_ISAR4_EL1),
 	ID_SANITISED(ID_ISAR5_EL1),
 	ID_SANITISED(ID_MMFR4_EL1),
-	ID_UNALLOCATED(2,7),
+	ID_SANITISED(ID_ISAR6_EL1),
 
 	/* CRm=3 */
 	ID_SANITISED(MVFR0_EL1),