arm64: cpufeature: Add cpufeature for IRQ priority masking

hulk inclusion
category: feature
bugzilla: 9291
CVE: NA

ported from https://lore.kernel.org/patchwork/patch/1037490/

--------------------------------

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: NJulien Thierry <julien.thierry@arm.com>
Reviewed-by: NSuzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: NMark Rutland <mark.rutland@arm.com>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Acked-by: NMarc Zyngier <marc.zyngier@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>
Signed-off-by: NWei Li <liwei391@huawei.com>
Reviewed-by: NHanjun Guo <guohanjun@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

arch/arm64/include/asm/cpucaps.h

@@ -52,7 +52,8 @@
 #define ARM64_MISMATCHED_CACHE_TYPE		31
 #define ARM64_HAS_STAGE2_FWB			32
 #define ARM64_HAS_MPAM				33
+#define ARM64_HAS_IRQ_PRIO_MASKING		34
 
-#define ARM64_NCAPS				34
+#define ARM64_NCAPS				35
 
 #endif /* __ASM_CPUCAPS_H */

arch/arm64/include/asm/cpufeature.h

@@ -508,6 +508,12 @@ static inline bool system_supports_sve(void)
 		cpus_have_const_cap(ARM64_SVE);
 }
 
+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

arch/arm64/kernel/cpufeature.c

@@ -1062,6 +1062,14 @@ static void cpu_has_fwb(const struct arm64_cpu_capabilities *__unused)
 	WARN_ON(val & (7 << 27 | 7 << 21));
 }
 
+#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",
@@ -1261,6 +1269,21 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.matches = has_hw_dbm,
 		.cpu_enable = cpu_enable_hw_dbm,
 	},
+#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
 	{},
 };