From: Kiryl Shutsemau <kirill@shutemov•name>
To: Catalin Marinas <catalin.marinas@arm•com>,
Will Deacon <will@kernel•org>, James Morse <james.morse@arm•com>
Cc: Mark Rutland <mark.rutland@arm•com>,
Marc Zyngier <maz@kernel•org>,
Doug Anderson <dianders@chromium•org>,
Petr Mladek <pmladek@suse•com>,
Thomas Gleixner <tglx@linutronix•de>,
Andrew Morton <akpm@linux-foundation•org>,
Baoquan He <bhe@redhat•com>, Puranjay Mohan <puranjay@kernel•org>,
Usama Arif <usama.arif@linux•dev>,
Breno Leitao <leitao@debian•org>,
Julien Thierry <julien.thierry.kdev@gmail•com>,
Lecopzer Chen <lecopzer.chen@mediatek•com>,
Sumit Garg <sumit.garg@kernel•org>,
kernel-team@meta•com, kexec@lists•infradead.org,
linux-arm-kernel@lists•infradead.org,
linux-kernel@vger•kernel.org,
"Kiryl Shutsemau (Meta)" <kas@kernel•org>
Subject: [PATCH 1/4] firmware: arm_sdei: add SDEI_EVENT_SIGNAL support
Date: Wed, 3 Jun 2026 15:36:32 +0100 [thread overview]
Message-ID: <ba8074cdb9ca5a471162cbc15f775c1567a3992a.1780496779.git.kas@kernel.org> (raw)
In-Reply-To: <cover.1780496779.git.kas@kernel.org>
From: "Kiryl Shutsemau (Meta)" <kas@kernel•org>
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) <kas@kernel•org>
---
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 f39ed7ba3a38..e3fd604d9894 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);
+
static void _ipi_private_reset(void *ignored)
{
int err;
diff --git a/include/linux/arm_sdei.h b/include/linux/arm_sdei.h
index f652a5028b59..3f3ec01155e8 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);
+
/* GHES register/unregister helpers */
int sdei_register_ghes(struct ghes *ghes, sdei_event_callback *normal_cb,
sdei_event_callback *critical_cb);
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)
--
2.54.0
next prev parent reply other threads:[~2026-06-03 14:36 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-03 14:36 [PATCH 0/4] arm64: cross-CPU NMI via SDEI Kiryl Shutsemau
2026-06-03 14:36 ` Kiryl Shutsemau [this message]
2026-06-03 14:36 ` [PATCH 2/4] drivers/firmware: add SDEI cross-CPU NMI service for arm64 Kiryl Shutsemau
2026-06-03 14:36 ` [PATCH 3/4] arm64: wire SDEI NMI into the hardlockup watchdog Kiryl Shutsemau
2026-06-03 14:36 ` [PATCH 4/4] arm64: route crash_smp_send_stop() last resort through SDEI Kiryl Shutsemau
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