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.

Kiryl Shutsemau (Meta) committed 4 months ago

Commit 9141eda1 parent 5686f2b3 files · +19 −0Browse files

Unified · Split

3 files

drivers/firmware/arm_sdei.c +12 −0
include/linux/arm_sdei.h +6 −0
include/uapi/linux/arm_sdei.h +1 −0

drivers/firmware/arm_sdei.c+12−0

@@ -339,6 +339,18 @@ static void _ipi_unmask_cpu(void *ignored) · 338 unmodified lines
339	339	sdei_unmask_local_cpu();
340	340	}
341	341
	342	+/*
	343	+ * Signal the software-signalled event (event 0) to @mpidr. Does nothing
	344	+ * but the SMC -- no locks, no event lookup -- so it is safe from NMI /
	345	+ * crash context (e.g. the cross-CPU NMI service).
	346	+ */
	347	+int sdei_event_signal(u32 event_num, u64 mpidr)
	348	+{
	349	+ return invoke_sdei_fn(SDEI_1_0_FN_SDEI_EVENT_SIGNAL, event_num,
	350	+ mpidr, 0, 0, 0, NULL);
	351	+}
	352	+NOKPROBE_SYMBOL(sdei_event_signal);
	353	+
342	354	/*
343	355	* Was SDEI firmware probed and is it usable? Lets optional consumers skip
344	356	* registering an event -- and the warning a failed registration emits -- on

include/linux/arm_sdei.h+6−0

@@ -37,6 +37,12 @@ int sdei_event_unregister(u32 event_num); · 36 unmodified lines
37	37	int sdei_event_enable(u32 event_num);
38	38	int sdei_event_disable(u32 event_num);
39	39
	40	+/*
	41	+ * Signal the software-signalled event (event 0) to another PE, NMI-like.
	42	+ * @mpidr is the target's MPIDR affinity.
	43	+ */
	44	+int sdei_event_signal(u32 event_num, u64 mpidr);
	45	+
40	46	/* Was SDEI firmware probed and usable? */
41	47	bool sdei_is_present(void);
42	48

include/uapi/linux/arm_sdei.h+1−0

@@ -22,6 +22,7 @@ · 21 unmodified lines
22	22	#define SDEI_1_0_FN_SDEI_PE_UNMASK SDEI_1_0_FN(0x0C)
23	23	#define SDEI_1_0_FN_SDEI_INTERRUPT_BIND SDEI_1_0_FN(0x0D)
24	24	#define SDEI_1_0_FN_SDEI_INTERRUPT_RELEASE SDEI_1_0_FN(0x0E)
	25	+#define SDEI_1_0_FN_SDEI_EVENT_SIGNAL SDEI_1_0_FN(0x0F)
25	26	#define SDEI_1_0_FN_SDEI_PRIVATE_RESET SDEI_1_0_FN(0x11)
26	27	#define SDEI_1_0_FN_SDEI_SHARED_RESET SDEI_1_0_FN(0x12)
27	28