From 9141eda9eec76b538bb64e89185034ec61d341ca Mon Sep 17 00:00:00 2001 From: "Kiryl Shutsemau (Meta)" Date: Mon, 29 Jun 2026 16:07:16 +0100 Subject: firmware: arm_sdei: add SDEI_EVENT_SIGNAL support Add sdei_event_signal(), a thin wrapper over the SDEI_EVENT_SIGNAL call (DEN0054) that makes the software-signalled event (event 0) pending on a target PE -- delivered NMI-like even when that PE has interrupts masked. It takes no locks, so it is safe to call from NMI / crash context. Signed-off-by: Kiryl Shutsemau (Meta) Reviewed-by: Douglas Anderson Tested-by: Yin Fengwei Signed-off-by: Will Deacon --- drivers/firmware/arm_sdei.c | 12 ++++++++++++ include/linux/arm_sdei.h | 6 ++++++ include/uapi/linux/arm_sdei.h | 1 + 3 files changed, 19 insertions(+) diff --git a/drivers/firmware/arm_sdei.c b/drivers/firmware/arm_sdei.c index c161cf263547..e8dd2f0f3919 100644 --- a/drivers/firmware/arm_sdei.c +++ b/drivers/firmware/arm_sdei.c @@ -339,6 +339,18 @@ static void _ipi_unmask_cpu(void *ignored) sdei_unmask_local_cpu(); } +/* + * Signal the software-signalled event (event 0) to @mpidr. Does nothing + * but the SMC -- no locks, no event lookup -- so it is safe from NMI / + * crash context (e.g. the cross-CPU NMI service). + */ +int sdei_event_signal(u32 event_num, u64 mpidr) +{ + return invoke_sdei_fn(SDEI_1_0_FN_SDEI_EVENT_SIGNAL, event_num, + mpidr, 0, 0, 0, NULL); +} +NOKPROBE_SYMBOL(sdei_event_signal); + /* * Was SDEI firmware probed and is it usable? Lets optional consumers skip * registering an event -- and the warning a failed registration emits -- on diff --git a/include/linux/arm_sdei.h b/include/linux/arm_sdei.h index b07113eeeff7..b9dc21c241be 100644 --- a/include/linux/arm_sdei.h +++ b/include/linux/arm_sdei.h @@ -37,6 +37,12 @@ int sdei_event_unregister(u32 event_num); int sdei_event_enable(u32 event_num); int sdei_event_disable(u32 event_num); +/* + * Signal the software-signalled event (event 0) to another PE, NMI-like. + * @mpidr is the target's MPIDR affinity. + */ +int sdei_event_signal(u32 event_num, u64 mpidr); + /* Was SDEI firmware probed and usable? */ bool sdei_is_present(void); diff --git a/include/uapi/linux/arm_sdei.h b/include/uapi/linux/arm_sdei.h index af0630ba5437..22eb61612673 100644 --- a/include/uapi/linux/arm_sdei.h +++ b/include/uapi/linux/arm_sdei.h @@ -22,6 +22,7 @@ #define SDEI_1_0_FN_SDEI_PE_UNMASK SDEI_1_0_FN(0x0C) #define SDEI_1_0_FN_SDEI_INTERRUPT_BIND SDEI_1_0_FN(0x0D) #define SDEI_1_0_FN_SDEI_INTERRUPT_RELEASE SDEI_1_0_FN(0x0E) +#define SDEI_1_0_FN_SDEI_EVENT_SIGNAL SDEI_1_0_FN(0x0F) #define SDEI_1_0_FN_SDEI_PRIVATE_RESET SDEI_1_0_FN(0x11) #define SDEI_1_0_FN_SDEI_SHARED_RESET SDEI_1_0_FN(0x12) -- cgit v1.2.3