arm64: sdei: abort running SDEI handlers during crash

Interrupts are blocked in SDEI context, per the SDEI spec: "The client
interrupts cannot preempt the event handler." If we crashed in the SDEI
handler-running context (as with ACPI's AGDI) then we need to clean up the
SDEI state before proceeding to the crash kernel so that the crash kernel
can have working interrupts.

Track the active SDEI handler per-cpu so that we can COMPLETE_AND_RESUME
the handler, discarding the interrupted context.

Fixes: f5df26961853 ("arm64: kernel: Add arch-specific SDEI entry code and CPU masking")
Signed-off-by: D Scott Phillips <scott@os.amperecomputing.com>
Cc: stable@vger.kernel.org
Reviewed-by: James Morse <james.morse@arm.com>
Tested-by: Mihai Carabas <mihai.carabas@oracle.com>
Link: https://lore.kernel.org/r/20230627002939.2758-1-scott@os.amperecomputing.com
Signed-off-by: Will Deacon <will@kernel.org>

1 files changed, 19 insertions, 0 deletions

diff --git a/drivers/firmware/arm_sdei.c b/drivers/firmware/arm_sdei.c
index f9040bd61081..285fe7ad490d 100644
--- a/drivers/firmware/arm_sdei.c
+++ b/drivers/firmware/arm_sdei.c
@@ -1095,3 +1095,22 @@ int sdei_event_handler(struct pt_regs *regs,
 	return err;
 }
 NOKPROBE_SYMBOL(sdei_event_handler);
+
+void sdei_handler_abort(void)
+{
+	/*
+	 * If the crash happened in an SDEI event handler then we need to
+	 * finish the handler with the firmware so that we can have working
+	 * interrupts in the crash kernel.
+	 */
+	if (__this_cpu_read(sdei_active_critical_event)) {
+	        pr_warn("still in SDEI critical event context, attempting to finish handler.\n");
+	        __sdei_handler_abort();
+	        __this_cpu_write(sdei_active_critical_event, NULL);
+	}
+	if (__this_cpu_read(sdei_active_normal_event)) {
+	        pr_warn("still in SDEI normal event context, attempting to finish handler.\n");
+	        __sdei_handler_abort();
+	        __this_cpu_write(sdei_active_normal_event, NULL);
+	}
+}