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authorDouglas Anderson <dianders@chromium.org>2023-11-07 18:26:56 +0300
committerCatalin Marinas <catalin.marinas@arm.com>2023-11-08 18:37:29 +0300
commit1d816ba168ea1999afe8cd2ccbe66b0e762bf455 (patch)
tree124e5d79d2a4f7f9e211c06b4f8b2b1422f6152d /arch/arm64
parent403edfa436286b21f5ffe6856ae5b36396e8966c (diff)
downloadlinux-1d816ba168ea1999afe8cd2ccbe66b0e762bf455.tar.xz
arm64: Move MediaTek GIC quirk handling from irqchip to core
In commit 44bd78dd2b88 ("irqchip/gic-v3: Disable pseudo NMIs on MediaTek devices w/ firmware issues") we added a method for detecting MediaTek devices with broken firmware and disabled pseudo-NMI. While that worked, it didn't address the problem at a deep enough level. The fundamental issue with this broken firmware is that it's not saving and restoring several important GICR registers. The current list is believed to be: * GICR_NUM_IPRIORITYR * GICR_CTLR * GICR_ISPENDR0 * GICR_ISACTIVER0 * GICR_NSACR Pseudo-NMI didn't work because it was the only thing (currently) in the kernel that relied on the broken registers, so forcing pseudo-NMI off was an effective fix. However, it could be observed that calling system_uses_irq_prio_masking() on these systems still returned "true". That caused confusion and led to the need for commit a07a59415217 ("arm64: smp: avoid NMI IPIs with broken MediaTek FW"). It's worried that the incorrect value returned by system_uses_irq_prio_masking() on these systems will continue to confuse future developers. Let's fix the issue a little more completely by disabling IRQ priorities at a deeper level in the kernel. Once we do this we can revert some of the other bits of code dealing with this quirk. This includes a partial revert of commit 44bd78dd2b88 ("irqchip/gic-v3: Disable pseudo NMIs on MediaTek devices w/ firmware issues"). This isn't a full revert because it leaves some of the changes to the "quirks" structure around in case future code needs it. Suggested-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20231107072651.v2.1.Ide945748593cffd8ff0feb9ae22b795935b944d6@changeid Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64')
-rw-r--r--arch/arm64/kernel/cpufeature.c46
1 files changed, 38 insertions, 8 deletions
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index f6b2e2906fc9..646591c67e7a 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -999,6 +999,37 @@ static void init_32bit_cpu_features(struct cpuinfo_32bit *info)
init_cpu_ftr_reg(SYS_MVFR2_EL1, info->reg_mvfr2);
}
+#ifdef CONFIG_ARM64_PSEUDO_NMI
+static bool enable_pseudo_nmi;
+
+static int __init early_enable_pseudo_nmi(char *p)
+{
+ return kstrtobool(p, &enable_pseudo_nmi);
+}
+early_param("irqchip.gicv3_pseudo_nmi", early_enable_pseudo_nmi);
+
+static __init void detect_system_supports_pseudo_nmi(void)
+{
+ struct device_node *np;
+
+ if (!enable_pseudo_nmi)
+ return;
+
+ /*
+ * Detect broken MediaTek firmware that doesn't properly save and
+ * restore GIC priorities.
+ */
+ np = of_find_compatible_node(NULL, NULL, "arm,gic-v3");
+ if (np && of_property_read_bool(np, "mediatek,broken-save-restore-fw")) {
+ pr_info("Pseudo-NMI disabled due to MediaTek Chromebook GICR save problem\n");
+ enable_pseudo_nmi = false;
+ }
+ of_node_put(np);
+}
+#else /* CONFIG_ARM64_PSEUDO_NMI */
+static inline void detect_system_supports_pseudo_nmi(void) { }
+#endif
+
void __init init_cpu_features(struct cpuinfo_arm64 *info)
{
/* Before we start using the tables, make sure it is sorted */
@@ -1058,6 +1089,13 @@ void __init init_cpu_features(struct cpuinfo_arm64 *info)
init_cpucap_indirect_list();
/*
+ * Detect broken pseudo-NMI. Must be called _before_ the call to
+ * setup_boot_cpu_capabilities() since it interacts with
+ * can_use_gic_priorities().
+ */
+ detect_system_supports_pseudo_nmi();
+
+ /*
* Detect and enable early CPU capabilities based on the boot CPU,
* after we have initialised the CPU feature infrastructure.
*/
@@ -2085,14 +2123,6 @@ static void cpu_enable_e0pd(struct arm64_cpu_capabilities const *cap)
#endif /* CONFIG_ARM64_E0PD */
#ifdef CONFIG_ARM64_PSEUDO_NMI
-static bool enable_pseudo_nmi;
-
-static int __init early_enable_pseudo_nmi(char *p)
-{
- return kstrtobool(p, &enable_pseudo_nmi);
-}
-early_param("irqchip.gicv3_pseudo_nmi", early_enable_pseudo_nmi);
-
static bool can_use_gic_priorities(const struct arm64_cpu_capabilities *entry,
int scope)
{