arm64: cpufeature: Detect CPU RAS Extentions

ARM's v8.2 Extentions add support for Reliability, Availability and
Serviceability (RAS). On CPUs with these extensions system software
can use additional barriers to isolate errors and determine if faults
are pending. Add cpufeature detection.

Platform level RAS support may require additional firmware support.

Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com>
[Rebased added config option, reworded commit message]
Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 664fadc..1d51c8e 100644 (file)
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1062,6 +1062,22 @@ config ARM64_PMEM
          operations if DC CVAP is not supported (following the behaviour of
          DC CVAP itself if the system does not define a point of persistence).
 
+config ARM64_RAS_EXTN
+       bool "Enable support for RAS CPU Extensions"
+       default y
+       help
+         CPUs that support the Reliability, Availability and Serviceability
+         (RAS) Extensions, part of ARMv8.2 are able to track faults and
+         errors, classify them and report them to software.
+
+         On CPUs with these extensions system software can use additional
+         barriers to determine if faults are pending and read the
+         classification from a new set of registers.
+
+         Selecting this feature will allow the kernel to use these barriers
+         and access the new registers if the system supports the extension.
+         Platform RAS features may additionally depend on firmware support.
+
 endmenu
 
 config ARM64_SVE

diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index 7049b48..bb26382 100644 (file)
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -44,7 +44,8 @@
 #define ARM64_UNMAP_KERNEL_AT_EL0              23
 #define ARM64_HARDEN_BRANCH_PREDICTOR          24
 #define ARM64_HARDEN_BP_POST_GUEST_EXIT                25
+#define ARM64_HAS_RAS_EXTN                     26
 
-#define ARM64_NCAPS                            26
+#define ARM64_NCAPS                            27
 
 #endif /* __ASM_CPUCAPS_H */

diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index 1a8108f..321622e 100644 (file)
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -498,6 +498,7 @@
 #define ID_AA64PFR0_CSV3_SHIFT         60
 #define ID_AA64PFR0_CSV2_SHIFT         56
 #define ID_AA64PFR0_SVE_SHIFT          32
+#define ID_AA64PFR0_RAS_SHIFT          28
 #define ID_AA64PFR0_GIC_SHIFT          24
 #define ID_AA64PFR0_ASIMD_SHIFT                20
 #define ID_AA64PFR0_FP_SHIFT           16
@@ -507,6 +508,7 @@
 #define ID_AA64PFR0_EL0_SHIFT          0
 
 #define ID_AA64PFR0_SVE                        0x1
+#define ID_AA64PFR0_RAS_V1             0x1
 #define ID_AA64PFR0_FP_NI              0xf
 #define ID_AA64PFR0_FP_SUPPORTED       0x0
 #define ID_AA64PFR0_ASIMD_NI           0xf

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 630a40e..116a5c9 100644 (file)
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -149,6 +149,7 @@ static const struct arm64_ftr_bits ftr_id_aa64pfr0[] = {
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_CSV3_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_CSV2_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_SVE_SHIFT, 4, 0),
+       ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_RAS_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_GIC_SHIFT, 4, 0),
        S_ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_ASIMD_SHIFT, 4, ID_AA64PFR0_ASIMD_NI),
        S_ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_FP_SHIFT, 4, ID_AA64PFR0_FP_NI),
@@ -1028,6 +1029,18 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
                .enable = sve_kernel_enable,
        },
 #endif /* CONFIG_ARM64_SVE */
+#ifdef CONFIG_ARM64_RAS_EXTN
+       {
+               .desc = "RAS Extension Support",
+               .capability = ARM64_HAS_RAS_EXTN,
+               .def_scope = SCOPE_SYSTEM,
+               .matches = has_cpuid_feature,
+               .sys_reg = SYS_ID_AA64PFR0_EL1,
+               .sign = FTR_UNSIGNED,
+               .field_pos = ID_AA64PFR0_RAS_SHIFT,
+               .min_field_value = ID_AA64PFR0_RAS_V1,
+       },
+#endif /* CONFIG_ARM64_RAS_EXTN */
        {},
 };