[PATCH v7 04/25] arm64: cpufeature: Add cpufeature for IRQ priority masking

[Julien Thierry <julien.thierry@arm.com>]

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.thierry@arm.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@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..149bf1e 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_uses_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 865bb55..4426b5b 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