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Subject[PATCH v6 24/24] arm64: Enable the support of pseudo-NMIs
Date
Add a build option and a command line parameter to build and enable the
support of pseudo-NMIs.

Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Suggested-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
Documentation/admin-guide/kernel-parameters.txt | 6 ++++++
arch/arm64/Kconfig | 14 ++++++++++++++
arch/arm64/kernel/cpufeature.c | 11 ++++++++++-
3 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 81d1d5a..63dbd56 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1183,6 +1183,12 @@
to discrete, to make X server driver able to add WB
entry later. This parameter enables that.

+ enable_pseudo_nmi [ARM64]
+ Enables support for pseudo-NMIs in the kernel. This
+ requires both the kernel to be built with
+ CONFIG_ARM64_PSEUDO_NMI and to be running on a
+ platform with GICv3.
+
enable_timer_pin_1 [X86]
Enable PIN 1 of APIC timer
Can be useful to work around chipset bugs
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 787d785..4729cf0 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -958,6 +958,20 @@ config ARM64_SSBD

If unsure, say Y.

+config ARM64_PSEUDO_NMI
+ bool "Support for NMI-like interrupts"
+ select CONFIG_ARM_GIC_V3
+ help
+ Adds support for mimicking Non-Maskable Interrupts through the use of
+ GIC interrupt priority. This support requires version 3 or later of
+ Arm GIC.
+
+ This high priority configuration for interrupts need to be
+ explicitly enabled through the new kernel parameter
+ "enable_pseudo_nmi".
+
+ If unsure, say N
+
menuconfig ARMV8_DEPRECATED
bool "Emulate deprecated/obsolete ARMv8 instructions"
depends on COMPAT
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 58a4978..acf1d06 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1149,10 +1149,19 @@ static void cpu_clear_disr(const struct arm64_cpu_capabilities *__unused)
#endif /* CONFIG_ARM64_RAS_EXTN */

#ifdef CONFIG_ARM64_PSEUDO_NMI
+static bool enable_pseudo_nmi;
+
+static int __init early_enable_pseudo_nmi(char *p)
+{
+ enable_pseudo_nmi = true;
+ return 0;
+}
+early_param("enable_pseudo_nmi", early_enable_pseudo_nmi);
+
static bool can_use_gic_priorities(const struct arm64_cpu_capabilities *entry,
int scope)
{
- return false;
+ return enable_pseudo_nmi && has_useable_gicv3_cpuif(entry, scope);
}
#endif

--
1.9.1
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