arm64/cpufeature: Introduce ID_PFR2 CPU register

This adds basic building blocks required for ID_PFR2 CPU register which
provides information about the AArch32 programmers model which must be
interpreted along with ID_PFR0 and ID_PFR1 CPU registers. This is added
per ARM DDI 0487F.a specification.

Cc: Catalin Marinas <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Marc Zyngier <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: James Morse <[email protected]>
Cc: Suzuki K Poulose <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]

Suggested-by: Mark Rutland <[email protected]>
Signed-off-by: Anshuman Khandual <[email protected]>
Reviewed-by: Suzuki K Poulose <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Will Deacon <[email protected]>

Author: Anshuman Khandual

arch/arm64/include/asm/cpu.h

@@ -46,6 +46,7 @@ struct cpuinfo_arm64 {
 	u32		reg_id_mmfr3;
 	u32		reg_id_pfr0;
 	u32		reg_id_pfr1;
+	u32		reg_id_pfr2;
 
 	u32		reg_mvfr0;
 	u32		reg_mvfr1;

arch/arm64/include/asm/sysreg.h

@@ -138,6 +138,7 @@
 
 #define SYS_ID_PFR0_EL1			sys_reg(3, 0, 0, 1, 0)
 #define SYS_ID_PFR1_EL1			sys_reg(3, 0, 0, 1, 1)
+#define SYS_ID_PFR2_EL1			sys_reg(3, 0, 0, 3, 4)
 #define SYS_ID_DFR0_EL1			sys_reg(3, 0, 0, 1, 2)
 #define SYS_ID_AFR0_EL1			sys_reg(3, 0, 0, 1, 3)
 #define SYS_ID_MMFR0_EL1		sys_reg(3, 0, 0, 1, 4)
@@ -789,6 +790,9 @@
 #define ID_ISAR6_DP_SHIFT		4
 #define ID_ISAR6_JSCVT_SHIFT		0
 
+#define ID_PFR2_SSBS_SHIFT		4
+#define ID_PFR2_CSV3_SHIFT		0
+
 #define MVFR0_FPROUND_SHIFT		28
 #define MVFR0_FPSHVEC_SHIFT		24
 #define MVFR0_FPSQRT_SHIFT		20

arch/arm64/kernel/cpufeature.c

@@ -439,6 +439,12 @@ static const struct arm64_ftr_bits ftr_id_pfr1[] = {
 	ARM64_FTR_END,
 };
 
+static const struct arm64_ftr_bits ftr_id_pfr2[] = {
+	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_PFR2_SSBS_SHIFT, 4, 0),
+	ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_PFR2_CSV3_SHIFT, 4, 0),
+	ARM64_FTR_END,
+};
+
 static const struct arm64_ftr_bits ftr_id_dfr0[] = {
 	/* [31:28] TraceFilt */
 	S_ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 24, 4, 0xf),	/* PerfMon */
@@ -520,6 +526,7 @@ static const struct __ftr_reg_entry {
 	ARM64_FTR_REG(SYS_MVFR0_EL1, ftr_generic_32bits),
 	ARM64_FTR_REG(SYS_MVFR1_EL1, ftr_generic_32bits),
 	ARM64_FTR_REG(SYS_MVFR2_EL1, ftr_mvfr2),
+	ARM64_FTR_REG(SYS_ID_PFR2_EL1, ftr_id_pfr2),
 
 	/* Op1 = 0, CRn = 0, CRm = 4 */
 	ARM64_FTR_REG(SYS_ID_AA64PFR0_EL1, ftr_id_aa64pfr0),
@@ -726,6 +733,7 @@ void __init init_cpu_features(struct cpuinfo_arm64 *info)
 		init_cpu_ftr_reg(SYS_ID_MMFR3_EL1, info->reg_id_mmfr3);
 		init_cpu_ftr_reg(SYS_ID_PFR0_EL1, info->reg_id_pfr0);
 		init_cpu_ftr_reg(SYS_ID_PFR1_EL1, info->reg_id_pfr1);
+		init_cpu_ftr_reg(SYS_ID_PFR2_EL1, info->reg_id_pfr2);
 		init_cpu_ftr_reg(SYS_MVFR0_EL1, info->reg_mvfr0);
 		init_cpu_ftr_reg(SYS_MVFR1_EL1, info->reg_mvfr1);
 		init_cpu_ftr_reg(SYS_MVFR2_EL1, info->reg_mvfr2);
@@ -859,6 +867,8 @@ static int update_32bit_cpu_features(int cpu, struct cpuinfo_arm64 *info,
 				      info->reg_id_pfr0, boot->reg_id_pfr0);
 	taint |= check_update_ftr_reg(SYS_ID_PFR1_EL1, cpu,
 				      info->reg_id_pfr1, boot->reg_id_pfr1);
+	taint |= check_update_ftr_reg(SYS_ID_PFR2_EL1, cpu,
+				      info->reg_id_pfr2, boot->reg_id_pfr2);
 	taint |= check_update_ftr_reg(SYS_MVFR0_EL1, cpu,
 				      info->reg_mvfr0, boot->reg_mvfr0);
 	taint |= check_update_ftr_reg(SYS_MVFR1_EL1, cpu,
@@ -986,6 +996,7 @@ static u64 __read_sysreg_by_encoding(u32 sys_id)
 	switch (sys_id) {
 	read_sysreg_case(SYS_ID_PFR0_EL1);
 	read_sysreg_case(SYS_ID_PFR1_EL1);
+	read_sysreg_case(SYS_ID_PFR2_EL1);
 	read_sysreg_case(SYS_ID_DFR0_EL1);
 	read_sysreg_case(SYS_ID_MMFR0_EL1);
 	read_sysreg_case(SYS_ID_MMFR1_EL1);

arch/arm64/kernel/cpuinfo.c

@@ -375,6 +375,7 @@ static void __cpuinfo_store_cpu(struct cpuinfo_arm64 *info)
 		info->reg_id_mmfr3 = read_cpuid(ID_MMFR3_EL1);
 		info->reg_id_pfr0 = read_cpuid(ID_PFR0_EL1);
 		info->reg_id_pfr1 = read_cpuid(ID_PFR1_EL1);
+		info->reg_id_pfr2 = read_cpuid(ID_PFR2_EL1);
 
 		info->reg_mvfr0 = read_cpuid(MVFR0_EL1);
 		info->reg_mvfr1 = read_cpuid(MVFR1_EL1);

arch/arm64/kvm/sys_regs.c

@@ -1456,7 +1456,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 	ID_SANITISED(MVFR1_EL1),
 	ID_SANITISED(MVFR2_EL1),
 	ID_UNALLOCATED(3,3),
-	ID_UNALLOCATED(3,4),
+	ID_SANITISED(ID_PFR2_EL1),
 	ID_UNALLOCATED(3,5),
 	ID_UNALLOCATED(3,6),
 	ID_UNALLOCATED(3,7),