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Thu, 27 Nov 2025 04:53:26 -0800 (PST) From: Yunhui Cui To: conor@kernel.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr, cuiyunhui@bytedance.com, luxu.kernel@bytedance.com, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, jassisinghbrar@gmail.com, conor.dooley@microchip.com, valentina.fernandezalanis@microchip.com, catalin.marinas@arm.com, will@kernel.org, maz@kernel.org, timothy.hayes@arm.com, lpieralisi@kernel.org, arnd@arndb.de, kees@kernel.org, tglx@linutronix.de, viresh.kumar@linaro.org, boqun.feng@gmail.com, linux-arm-kernel@lists.infradead.org, cleger@rivosinc.com, atishp@rivosinc.com, ajones@ventanamicro.com Subject: [PATCH v3 1/8] drivers: firmware: riscv: add SSE NMI support Date: Thu, 27 Nov 2025 20:52:58 +0800 Message-Id: <20251127125305.89961-2-cuiyunhui@bytedance.com> X-Mailer: git-send-email 2.39.2 (Apple Git-143) In-Reply-To: <20251127125305.89961-1-cuiyunhui@bytedance.com> References: <20251127125305.89961-1-cuiyunhui@bytedance.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add support for handling Non-Maskable Interrupts (NMIs) through the RISC-V Supervisor Software Events (SSE) framework. Add basic NMI functionality via SBI_SSE_EVENT_LOCAL_SOFTWARE_INJECTED registration and enabling. Signed-off-by: Yunhui Cui --- MAINTAINERS | 8 +++ drivers/firmware/riscv/Kconfig | 10 +++ drivers/firmware/riscv/Makefile | 1 + drivers/firmware/riscv/riscv_sse_nmi.c | 90 ++++++++++++++++++++++++++ include/linux/riscv_sse_nmi.h | 26 ++++++++ 5 files changed, 135 insertions(+) create mode 100644 drivers/firmware/riscv/riscv_sse_nmi.c create mode 100644 include/linux/riscv_sse_nmi.h diff --git a/MAINTAINERS b/MAINTAINERS index 8bf5416953f45..c06658da8af96 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -22057,6 +22057,14 @@ S: Maintained F: drivers/firmware/riscv/riscv_sse.c F: include/linux/riscv_sse.h =20 +RISC-V SSE NMI SUPPORT +M: Yunhui Cui +R: Xu Lu +L: linux-riscv@lists.infradead.org +S: Maintained +F: drivers/firmware/riscv/riscv_sse_nmi.c +F: include/linux/riscv_sse_nmi.h + RISC-V THEAD SoC SUPPORT M: Drew Fustini M: Guo Ren diff --git a/drivers/firmware/riscv/Kconfig b/drivers/firmware/riscv/Kconfig index ed5b663ac5f91..6c77c7823571a 100644 --- a/drivers/firmware/riscv/Kconfig +++ b/drivers/firmware/riscv/Kconfig @@ -12,4 +12,14 @@ config RISCV_SBI_SSE this option provides support to register callbacks on specific SSE events. =20 +config RISCV_SSE_NMI + bool "Enable SBI Supervisor Software Events NMI support" + depends on RISCV_SBI_SSE && SMP + default y + help + This option enables support for delivering Non-Maskable Interrupt + (NMI) notifications through the Supervisor Software Events (SSE) + framework. When enabled, the system can deliver local, unknown and + other types of NMIs. + endmenu diff --git a/drivers/firmware/riscv/Makefile b/drivers/firmware/riscv/Makef= ile index c8795d4bbb2ea..fbc182b53ae53 100644 --- a/drivers/firmware/riscv/Makefile +++ b/drivers/firmware/riscv/Makefile @@ -1,3 +1,4 @@ # SPDX-License-Identifier: GPL-2.0 =20 obj-$(CONFIG_RISCV_SBI_SSE) +=3D riscv_sbi_sse.o +obj-$(CONFIG_RISCV_SSE_NMI) +=3D riscv_sse_nmi.o diff --git a/drivers/firmware/riscv/riscv_sse_nmi.c b/drivers/firmware/risc= v/riscv_sse_nmi.c new file mode 100644 index 0000000000000..752ee88b230da --- /dev/null +++ b/drivers/firmware/riscv/riscv_sse_nmi.c @@ -0,0 +1,90 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ + +#define pr_fmt(fmt) "SSE NMI: " fmt + +#include +#include +#include + +#include +#include +#include + +static bool nmi_available; +static struct sse_event *local_nmi_evt; +static DEFINE_PER_CPU(atomic_t, local_nmi) =3D ATOMIC_INIT(LOCAL_NMI_NONE); + +bool nmi_support(void) +{ + return READ_ONCE(nmi_available); +} + +static inline struct sbiret sbi_sse_ecall(int fid, unsigned long arg0, + unsigned long arg1) +{ + return sbi_ecall(SBI_EXT_SSE, fid, arg0, arg1, 0, 0, 0, 0); +} + +void send_nmi_single(unsigned int cpu, enum local_nmi_type type) +{ + unsigned int hart_id =3D cpuid_to_hartid_map(cpu); + u32 evt =3D SBI_SSE_EVENT_LOCAL_SOFTWARE_INJECTED; + struct sbiret ret; + + atomic_or(type, per_cpu_ptr(&local_nmi, cpu)); + + ret =3D sbi_sse_ecall(SBI_SSE_EVENT_INJECT, evt, hart_id); + if (ret.error) + pr_err("Failed to signal event %x to hartid %d, error %ld\n", + evt, hart_id, ret.error); +} + +void send_nmi_mask(cpumask_t *mask, enum local_nmi_type type) +{ + unsigned int cpu; + + for_each_cpu(cpu, mask) + send_nmi_single(cpu, type); +} + +static int local_nmi_handler(u32 evt, void *arg, struct pt_regs *regs) +{ + return 0; +} + +static int __init local_nmi_init(void) +{ + int ret; + + local_nmi_evt =3D sse_event_register(SBI_SSE_EVENT_LOCAL_SOFTWARE_INJECTE= D, 0, + local_nmi_handler, NULL); + if (IS_ERR(local_nmi_evt)) + return PTR_ERR(local_nmi_evt); + + ret =3D sse_event_enable(local_nmi_evt); + if (ret) { + sse_event_unregister(local_nmi_evt); + return ret; + } + + pr_info("Using SSE for Local NMI event delivery\n"); + + return 0; +} + +static int __init sse_nmi_init(void) +{ + int ret; + + ret =3D local_nmi_init(); + if (ret) { + pr_err("Local_nmi_init failed with error %d\n", ret); + return ret; + } + + WRITE_ONCE(nmi_available, true); + + return 0; +} + +late_initcall(sse_nmi_init); diff --git a/include/linux/riscv_sse_nmi.h b/include/linux/riscv_sse_nmi.h new file mode 100644 index 0000000000000..16db85c5162f5 --- /dev/null +++ b/include/linux/riscv_sse_nmi.h @@ -0,0 +1,26 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ + +#ifndef __LINUX_RISCV_SSE_NMI_H +#define __LINUX_RISCV_SSE_NMI_H + +#include + +enum local_nmi_type { + LOCAL_NMI_NONE =3D 0U, + LOCAL_NMI_STOP =3D BIT(0), + LOCAL_NMI_CRASH =3D BIT(1), + LOCAL_NMI_BACKTRACE =3D BIT(2), + LOCAL_NMI_KGDB =3D BIT(3), +}; + +#ifdef CONFIG_RISCV_SSE_NMI +bool nmi_support(void); +void send_nmi_mask(cpumask_t *mask, enum local_nmi_type type); +void send_nmi_single(unsigned int cpu, enum local_nmi_type type); +#else +static inline bool nmi_support(void) { return false; } +static inline void send_nmi_mask(cpumask_t *mask) { }; +static inline void send_nmi_single(unsigned int cpu) { }; +#endif + +#endif --=20 2.39.5