Re: [PATCH] arm64: Introduce ISAR6 CPU ID register

From: Marc Zyngier
Date: Thu Dec 12 2019 - 06:43:55 EST

On 2019-12-12 10:14, Anshuman Khandual wrote:
This adds basic building blocks required for ISAR6 CPU ID register which
identifies support for various instruction implementation on AArch32 state.

nit: the register name is ID_ISAR6.


Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Marc Zyngier <maz@xxxxxxxxxx>
Cc: James Morse <james.morse@xxxxxxx>
Cc: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: kvmarm@xxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
---
arch/arm64/include/asm/cpu.h | 1 +
arch/arm64/include/asm/sysreg.h | 9 +++++++++
arch/arm64/kernel/cpufeature.c | 7 ++++++-
arch/arm64/kernel/cpuinfo.c | 1 +
arch/arm64/kvm/sys_regs.c | 2 +-
5 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/cpu.h b/arch/arm64/include/asm/cpu.h
index d72d995..b4a4053 100644
--- a/arch/arm64/include/asm/cpu.h
+++ b/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;
diff --git a/arch/arm64/include/asm/sysreg.h
b/arch/arm64/include/asm/sysreg.h
index 6db3a9b..4fd3327 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/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)
@@ -683,6 +684,14 @@
#define ID_ISAR5_AES_SHIFT 4
#define ID_ISAR5_SEVL_SHIFT 0

+#define ID_ISAR6_JSCVT_SHIFT 0
+#define ID_ISAR6_DP_SHIFT 4
+#define ID_ISAR6_FHM_SHIFT 8
+#define ID_ISAR6_SB_SHIFT 12
+#define ID_ISAR6_SPECRES_SHIFT 16
+#define ID_ISAR6_BF16_SHIFT 20
+#define ID_ISAR6_I8MM_SHIFT 24

I couldn't find the last two items in the E.a revision of the ARMv8 ARM.
I guess they are for post 8.5 revisions of the architecture?

+
#define MVFR0_FPROUND_SHIFT 28
#define MVFR0_FPSHVEC_SHIFT 24
#define MVFR0_FPSQRT_SHIFT 20
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index f344cea..3b9ac8b 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -346,7 +346,7 @@ static const struct arm64_ftr_bits ftr_zcr[] = {
* Common ftr bits for a 32bit register with all hidden, strict
* attributes, with 4bit feature fields and a default safe value of
* 0. Covers the following 32bit registers:
- * id_isar[0-4], id_mmfr[1-3], id_pfr1, mvfr[0-1]
+ * id_isar[0-4, 6], id_mmfr[1-3], id_pfr1, mvfr[0-1]
*/
static const struct arm64_ftr_bits ftr_generic_32bits[] = {
ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 28, 4, 0),
@@ -399,6 +399,7 @@ 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_generic_32bits),

/* Op1 = 0, CRn = 0, CRm = 3 */
ARM64_FTR_REG(SYS_MVFR0_EL1, ftr_generic_32bits),
@@ -603,6 +604,7 @@ 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);
@@ -756,6 +758,8 @@ 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
@@ -834,6 +838,7 @@ 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);
diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
index 10121f5..6005d38 100644
--- a/arch/arm64/kernel/cpuinfo.c
+++ b/arch/arm64/kernel/cpuinfo.c
@@ -362,6 +362,7 @@ 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);
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 7dadd24..a6b8ca1 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/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),

Otherwise,

Acked-by: Marc Zyngier <maz@xxxxxxxxxx>

M.
--
Jazz is not dead. It just smells funny...