Re: [PATCH v4 1/5] arm64: Add framework to turn IPI as NMI
From: Sumit Garg <hidden>
Date: 2020-10-12 12:19:27
Also in:
lkml
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
Hi Masa, On Sat, 10 Oct 2020 at 20:43, Masayoshi Mizuma [off-list ref] wrote:
On Sat, Oct 10, 2020 at 10:34:04AM +0100, Marc Zyngier wrote:quoted
On Sat, 10 Oct 2020 02:58:55 +0100, Masayoshi Mizuma [off-list ref] wrote: [...]quoted
quoted
+void ipi_nmi_setup(int cpu) +{ + if (!ipi_desc) + return;ipi_nmi_setup() may be called twice for CPU0: set_smp_ipi_range => set_smp_ipi_nmi => ipi_nmi_setup => ipi_setup => ipi_nmi_setup Actually, I got the following error message via the second ipi_nmi_setup(): GICv3: Pseudo-NMIs enabled using relaxed ICC_PMR_EL1 synchronisation GICv3: Cannot set NMI property of enabled IRQ 8 genirq: Failed to setup NMI delivery: irq 8
Ah, thanks for catching this which I missed during my testing.
quoted hunk ↗ jump to hunk
quoted
quoted
Why don't we have a check to prevent that? Like as: if (cpumask_test_cpu(cpu, ipi_desc->percpu_enabled)) return;That's definitely the wrong thing to do. prepare_nmi_setup() shouldn't be called twice, and papering over it isn't acceptable.Got it. How about moving ipi_nmi_setup() from ipi_setup() to secondary_start_kernel() ? so that CPU0 can call ipi_nmi_setup() only from set_smp_ipi_nmi().--- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c@@ -245,6 +245,7 @@ asmlinkage notrace void secondary_start_kernel(void) notify_cpu_starting(cpu); ipi_setup(cpu); + ipi_nmi_setup(cpu); store_cpu_topology(cpu); numa_add_cpu(cpu);@@ -966,8 +967,6 @@ static void ipi_setup(int cpu) for (i = 0; i < nr_ipi; i++) enable_percpu_irq(ipi_irq_base + i, 0); - - ipi_nmi_setup(cpu); } #ifdef CONFIG_HOTPLUG_CPU
IMO, it would be more consistent to keep invocation of ipi_nmi_setup() from ipi_setup(). So let me remove other invocation from set_smp_ipi_nmi():
diff --git a/arch/arm64/kernel/ipi_nmi.c b/arch/arm64/kernel/ipi_nmi.c
index d3aa430..000e457 100644
--- a/arch/arm64/kernel/ipi_nmi.c
+++ b/arch/arm64/kernel/ipi_nmi.c@@ -87,7 +87,4 @@ void __init set_smp_ipi_nmi(int ipi) ipi_desc = irq_to_desc(ipi); irq_set_status_flags(ipi, IRQ_HIDDEN); ipi_id = ipi; - - /* Setup the boot CPU immediately */ - ipi_nmi_setup(smp_processor_id()); }
Do let me know if this works for you? -Sumit
Thanks, Masa
_______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel