Add a cpufeature indicating whether a cpu supports masking interrupts
by priority.

The feature will be properly enabled in a later patch.

Signed-off-by: Julien Thierry <julien.thie...@arm.com>
Cc: Catalin Marinas <catalin.mari...@arm.com>
Cc: Will Deacon <will.dea...@arm.com>
Cc: Marc Zyngier <marc.zyng...@arm.com>
Cc: Suzuki K Poulose <suzuki.poul...@arm.com>
---
 arch/arm64/include/asm/cpucaps.h    |  3 ++-
 arch/arm64/include/asm/cpufeature.h |  6 ++++++
 arch/arm64/kernel/cpufeature.c      | 23 +++++++++++++++++++++++
 3 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index 6e2d254..f367e5c 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -54,7 +54,8 @@
 #define ARM64_HAS_CRC32                                33
 #define ARM64_SSBS                             34
 #define ARM64_WORKAROUND_1188873               35
+#define ARM64_HAS_IRQ_PRIO_MASKING             36
 
-#define ARM64_NCAPS                            36
+#define ARM64_NCAPS                            37
 
 #endif /* __ASM_CPUCAPS_H */
diff --git a/arch/arm64/include/asm/cpufeature.h 
b/arch/arm64/include/asm/cpufeature.h
index 7e2ec64..a6e063f 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -514,6 +514,12 @@ static inline bool system_supports_cnp(void)
                cpus_have_const_cap(ARM64_HAS_CNP);
 }
 
+static inline bool system_supports_irq_prio_masking(void)
+{
+       return IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) &&
+              cpus_have_const_cap(ARM64_HAS_IRQ_PRIO_MASKING);
+}
+
 #define ARM64_SSBD_UNKNOWN             -1
 #define ARM64_SSBD_FORCE_DISABLE       0
 #define ARM64_SSBD_KERNEL              1
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 03a9d96..1b5b553 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1145,6 +1145,14 @@ static void cpu_clear_disr(const struct 
arm64_cpu_capabilities *__unused)
 }
 #endif /* CONFIG_ARM64_RAS_EXTN */
 
+#ifdef CONFIG_ARM64_PSEUDO_NMI
+static bool can_use_gic_priorities(const struct arm64_cpu_capabilities *entry,
+                                  int scope)
+{
+       return false;
+}
+#endif
+
 static const struct arm64_cpu_capabilities arm64_features[] = {
        {
                .desc = "GIC system register CPU interface",
@@ -1368,6 +1376,21 @@ static void cpu_clear_disr(const struct 
arm64_cpu_capabilities *__unused)
                .cpu_enable = cpu_enable_cnp,
        },
 #endif
+#ifdef CONFIG_ARM64_PSEUDO_NMI
+       {
+               /*
+                * Depends on having GICv3
+                */
+               .desc = "IRQ priority masking",
+               .capability = ARM64_HAS_IRQ_PRIO_MASKING,
+               .type = ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE,
+               .matches = can_use_gic_priorities,
+               .sys_reg = SYS_ID_AA64PFR0_EL1,
+               .field_pos = ID_AA64PFR0_GIC_SHIFT,
+               .sign = FTR_UNSIGNED,
+               .min_field_value = 1,
+       },
+#endif
        {},
 };
 
-- 
1.9.1

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