From: Masayoshi Mizuma <msys.mizuma@gmail.com>
To: Sumit Garg <sumit.garg@linaro.org>
Cc: mark.rutland@arm.com, daniel.thompson@linaro.org,
ito-yuichi@fujitsu.com, jason@lakedaemon.net, maz@kernel.org,
jason.wessel@windriver.com, dianders@chromium.org,
linux-kernel@vger.kernel.org, julien.thierry.kdev@gmail.com,
catalin.marinas@arm.com, kgdb-bugreport@lists.sourceforge.net,
tglx@linutronix.de, will@kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v5 1/5] arm64: Add framework to turn IPI as NMI
Date: Wed, 14 Oct 2020 21:15:15 -0400 [thread overview]
Message-ID: <20201015011515.dhwgxki5eyewcgyv@gabell> (raw)
In-Reply-To: <1602673931-28782-2-git-send-email-sumit.garg@linaro.org>
On Wed, Oct 14, 2020 at 04:42:07PM +0530, Sumit Garg wrote:
> Introduce framework to turn an IPI as NMI using pseudo NMIs. In case a
> particular platform doesn't support pseudo NMIs, then request IPI as a
> regular IRQ.
>
> The main motivation for this feature is to have an IPI that can be
> leveraged to invoke NMI functions on other CPUs. And current prospective
> users are NMI backtrace and KGDB CPUs round-up whose support is added
> via future patches.
>
> Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
> ---
> arch/arm64/include/asm/nmi.h | 16 +++++++++
> arch/arm64/kernel/Makefile | 2 +-
> arch/arm64/kernel/ipi_nmi.c | 77 ++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 94 insertions(+), 1 deletion(-)
> create mode 100644 arch/arm64/include/asm/nmi.h
> create mode 100644 arch/arm64/kernel/ipi_nmi.c
>
> diff --git a/arch/arm64/include/asm/nmi.h b/arch/arm64/include/asm/nmi.h
> new file mode 100644
> index 0000000..3433c55
> --- /dev/null
> +++ b/arch/arm64/include/asm/nmi.h
> @@ -0,0 +1,16 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __ASM_NMI_H
> +#define __ASM_NMI_H
> +
> +#ifndef __ASSEMBLER__
> +
> +#include <linux/cpumask.h>
> +
> +extern void arch_send_call_nmi_func_ipi_mask(cpumask_t *mask);
> +
> +void set_smp_ipi_nmi(int ipi);
> +void ipi_nmi_setup(int cpu);
> +void ipi_nmi_teardown(int cpu);
> +
> +#endif /* !__ASSEMBLER__ */
> +#endif
> diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
> index bbaf0bc..525a1e0 100644
> --- a/arch/arm64/kernel/Makefile
> +++ b/arch/arm64/kernel/Makefile
> @@ -17,7 +17,7 @@ obj-y := debug-monitors.o entry.o irq.o fpsimd.o \
> return_address.o cpuinfo.o cpu_errata.o \
> cpufeature.o alternative.o cacheinfo.o \
> smp.o smp_spin_table.o topology.o smccc-call.o \
> - syscall.o proton-pack.o
> + syscall.o proton-pack.o ipi_nmi.o
>
> targets += efi-entry.o
>
> diff --git a/arch/arm64/kernel/ipi_nmi.c b/arch/arm64/kernel/ipi_nmi.c
> new file mode 100644
> index 0000000..a959256
> --- /dev/null
> +++ b/arch/arm64/kernel/ipi_nmi.c
> @@ -0,0 +1,77 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * NMI support for IPIs
> + *
> + * Copyright (C) 2020 Linaro Limited
> + * Author: Sumit Garg <sumit.garg@linaro.org>
> + */
> +
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/smp.h>
> +
> +#include <asm/nmi.h>
> +
> +static struct irq_desc *ipi_desc __read_mostly;
> +static int ipi_id __read_mostly;
> +static bool is_nmi __read_mostly;
> +
> +void arch_send_call_nmi_func_ipi_mask(cpumask_t *mask)
> +{
> + if (WARN_ON_ONCE(!ipi_desc))
> + return;
> +
> + __ipi_send_mask(ipi_desc, mask);
> +}
> +
> +static irqreturn_t ipi_nmi_handler(int irq, void *data)
> +{
> + /* nop, NMI handlers for special features can be added here. */
> +
> + return IRQ_HANDLED;
> +}
> +
> +void ipi_nmi_setup(int cpu)
> +{
> + if (!ipi_desc)
> + return;
> +
> + if (is_nmi) {
> + if (!prepare_percpu_nmi(ipi_id))
> + enable_percpu_nmi(ipi_id, IRQ_TYPE_NONE);
> + } else {
> + enable_percpu_irq(ipi_id, IRQ_TYPE_NONE);
> + }
> +}
> +
> +void ipi_nmi_teardown(int cpu)
> +{
> + if (!ipi_desc)
> + return;
> +
> + if (is_nmi) {
> + disable_percpu_nmi(ipi_id);
> + teardown_percpu_nmi(ipi_id);
> + } else {
> + disable_percpu_irq(ipi_id);
> + }
> +}
> +
> +void __init set_smp_ipi_nmi(int ipi)
> +{
> + int err;
> +
> + err = request_percpu_nmi(ipi, ipi_nmi_handler, "IPI", &cpu_number);
> + if (err) {
> + err = request_percpu_irq(ipi, ipi_nmi_handler, "IPI",
> + &cpu_number);
> + WARN_ON(err);
> + is_nmi = false;
> + } else {
> + is_nmi = true;
> + }
> +
> + ipi_desc = irq_to_desc(ipi);
> + irq_set_status_flags(ipi, IRQ_HIDDEN);
> + ipi_id = ipi;
> +}
> --
Looks good to me. Please feel free to add:
Reviewed-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Thanks!
Masa
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next prev parent reply other threads:[~2020-10-15 1:17 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-14 11:12 [PATCH v5 0/5] arm64: Add framework to turn an IPI as NMI Sumit Garg
2020-10-14 11:12 ` [PATCH v5 1/5] arm64: Add framework to turn " Sumit Garg
2020-10-15 1:15 ` Masayoshi Mizuma [this message]
2020-10-19 11:37 ` Marc Zyngier
2020-10-20 6:43 ` Sumit Garg
2020-10-20 10:08 ` Marc Zyngier
2020-10-20 11:22 ` Sumit Garg
2020-10-20 12:25 ` Daniel Thompson
2020-10-20 12:32 ` Marc Zyngier
2020-10-21 5:22 ` Sumit Garg
2020-10-21 10:27 ` Marc Zyngier
2020-10-22 11:52 ` Sumit Garg
2020-10-19 11:56 ` Marc Zyngier
2020-10-20 7:07 ` Sumit Garg
2020-10-14 11:12 ` [PATCH v5 2/5] irqchip/gic-v3: Enable support for SGIs to act as NMIs Sumit Garg
2020-10-15 1:16 ` Masayoshi Mizuma
2020-10-19 12:07 ` Marc Zyngier
2020-10-20 7:24 ` Sumit Garg
2020-10-14 11:12 ` [PATCH v5 3/5] arm64: smp: Allocate and setup IPI as NMI Sumit Garg
2020-10-15 1:16 ` Masayoshi Mizuma
2020-10-19 11:59 ` Marc Zyngier
2020-10-20 7:16 ` Sumit Garg
2020-10-14 11:12 ` [PATCH v5 4/5] arm64: kgdb: Round up cpus using " Sumit Garg
2020-10-19 12:15 ` Marc Zyngier
2020-10-20 8:51 ` Sumit Garg
2020-10-14 11:12 ` [PATCH v5 5/5] arm64: ipi_nmi: Add support for NMI backtrace Sumit Garg
2020-10-15 1:17 ` Masayoshi Mizuma
2020-10-19 12:20 ` Marc Zyngier
2020-10-20 9:13 ` Sumit Garg
2020-10-21 10:32 ` Marc Zyngier
2020-10-21 11:28 ` Sumit Garg
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