Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | From | Douglas Anderson <> | Subject | [PATCH v2 1/2] arm64: Move Mediatek GIC quirk handling from irqchip to core | Date | Tue, 7 Nov 2023 07:26:56 -0800 |
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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> ---
Changes in v2: - Just detect the quirk once at init time. - Fixed typo in subject: s/GiC/GIC. - Squash in ("Remove Mediatek pseudo-NMI firmware quirk handling").
arch/arm64/kernel/cpufeature.c | 46 ++++++++++++++++++++++++++++------ drivers/irqchip/irq-gic-v3.c | 22 +--------------- 2 files changed, 39 insertions(+), 29 deletions(-)
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index f6b2e2906fc9..928124ea2e96 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 */ @@ -1057,6 +1088,13 @@ 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) { diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c index 68d11ccee441..1ba674367ee3 100644 --- a/drivers/irqchip/irq-gic-v3.c +++ b/drivers/irqchip/irq-gic-v3.c @@ -39,8 +39,7 @@ #define FLAGS_WORKAROUND_GICR_WAKER_MSM8996 (1ULL << 0) #define FLAGS_WORKAROUND_CAVIUM_ERRATUM_38539 (1ULL << 1) -#define FLAGS_WORKAROUND_MTK_GICR_SAVE (1ULL << 2) -#define FLAGS_WORKAROUND_ASR_ERRATUM_8601001 (1ULL << 3) +#define FLAGS_WORKAROUND_ASR_ERRATUM_8601001 (1ULL << 2) #define GIC_IRQ_TYPE_PARTITION (GIC_IRQ_TYPE_LPI + 1) @@ -1779,15 +1778,6 @@ static bool gic_enable_quirk_msm8996(void *data) return true; } -static bool gic_enable_quirk_mtk_gicr(void *data) -{ - struct gic_chip_data *d = data; - - d->flags |= FLAGS_WORKAROUND_MTK_GICR_SAVE; - - return true; -} - static bool gic_enable_quirk_cavium_38539(void *data) { struct gic_chip_data *d = data; @@ -1888,11 +1878,6 @@ static const struct gic_quirk gic_quirks[] = { .compatible = "asr,asr8601-gic-v3", .init = gic_enable_quirk_asr8601, }, - { - .desc = "GICv3: Mediatek Chromebook GICR save problem", - .property = "mediatek,broken-save-restore-fw", - .init = gic_enable_quirk_mtk_gicr, - }, { .desc = "GICv3: HIP06 erratum 161010803", .iidr = 0x0204043b, @@ -1959,11 +1944,6 @@ static void gic_enable_nmi_support(void) if (!gic_prio_masking_enabled()) return; - if (gic_data.flags & FLAGS_WORKAROUND_MTK_GICR_SAVE) { - pr_warn("Skipping NMI enable due to firmware issues\n"); - return; - } - rdist_nmi_refs = kcalloc(gic_data.ppi_nr + SGI_NR, sizeof(*rdist_nmi_refs), GFP_KERNEL); if (!rdist_nmi_refs) -- 2.42.0.869.gea05f2083d-goog
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