[PATCH v4 21/26] arm64: Add build option for IRQ masking via priority

[Julien Thierry]

Provide a build option to enable using  GICv3 priorities to enable/disable
interrupts.

Signed-off-by: Julien Thierry <julien.thierry@xxxxxxx>
Suggested-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
---
 arch/arm64/Kconfig | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index eb2cf49..ab214b9 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -938,6 +938,21 @@ config HARDEN_EL2_VECTORS
 
 	  If unsure, say Y.
 
+config USE_ICC_SYSREGS_FOR_IRQFLAGS
+	bool "Use ICC system registers for IRQ masking"
+	select CONFIG_ARM_GIC_V3
+	help
+	  Using the ICC system registers for IRQ masking makes it possible
+	  to simulate NMI on ARM64 systems. This allows several interesting
+	  features (especially debug features) to be used on these systems.
+
+	  Say Y here to implement IRQ masking using ICC system
+	  registers when the GIC System Registers are available. The changes
+	  are applied dynamically using the alternatives system so it is safe
+	  to enable this option on systems with older interrupt controllers.
+
+	  If unsure, say N
+
 menuconfig ARMV8_DEPRECATED
 	bool "Emulate deprecated/obsolete ARMv8 instructions"
 	depends on COMPAT
-- 
1.9.1