Detect and mitigate uncontrolled ACPI GPE interrupt storms on OpenBSD (7.3, 7.3-current, 7.5-stable)

acpi.diff

diff --git sys/dev/acpi/acpi.c sys/dev/acpi/acpi.c
index 853bad1ab..26a5c1702 100644
--- sys/dev/acpi/acpi.c
+++ sys/dev/acpi/acpi.c
@@ -52,6 +52,9 @@
 #define APMDEV_NORMAL	0
 #define APMDEV_CTL	8
 
+#define GPE_RATE_MIN_CYCLE	5		/* seconds    */
+#define GPE_RATE_MAX		1000	/* per second */
+
 #include "wd.h"
 
 #ifdef ACPI_DEBUG
@@ -98,6 +101,8 @@ void	acpi_disable_allgpes(struct acpi_softc *);
 struct gpe_block *acpi_find_gpe(struct acpi_softc *, int);
 void	acpi_enable_onegpe(struct acpi_softc *, int);
 int	acpi_gpe(struct acpi_softc *, int, void *);
+void	acpi_init_gpe_rate(struct acpi_softc *, int);
+int	acpi_gpe_rate(struct acpi_softc *, int);
 
 void	acpi_enable_rungpes(struct acpi_softc *);
 
@@ -2229,6 +2234,7 @@ acpi_enable_onegpe(struct acpi_softc *sc, int gpe)
 	dnprintf(50, "enabling GPE %.2x (current: %sabled) %.2x\n",
 	    gpe, (en & mask) ? "en" : "dis", en);
 	acpi_write_pmreg(sc, ACPIREG_GPE_EN, gpe>>3, en | mask);
+	acpi_init_gpe_rate(sc, gpe);
 }
 
 /* Clear all GPEs */
@@ -2307,7 +2313,40 @@ acpi_gpe(struct acpi_softc *sc, int gpe, void *arg)
 	if (sc->gpe_table[gpe].flags & GPE_LEVEL)
 		acpi_write_pmreg(sc, ACPIREG_GPE_STS, gpe>>3, mask);
 	en = acpi_read_pmreg(sc, ACPIREG_GPE_EN,  gpe>>3);
-	acpi_write_pmreg(sc, ACPIREG_GPE_EN,  gpe>>3, en | mask);
+	/* Re-enable if GPE rate passes, otherwise leave disabled */
+	if (!acpi_gpe_rate(sc, gpe))
+		acpi_write_pmreg(sc, ACPIREG_GPE_EN,  gpe>>3, en | mask);
+	return (0);
+}
+
+void
+acpi_init_gpe_rate(struct acpi_softc *sc, int gpe)
+{
+	sc->gpe_table[gpe].rate_start = getuptime();
+	sc->gpe_table[gpe].rate_count = 0;
+}
+
+int
+acpi_gpe_rate(struct acpi_softc *sc, int gpe)
+{
+	struct gpe_block *pgpe = &sc->gpe_table[gpe];
+	time_t cycle;
+
+	pgpe->rate_count++;
+	dnprintf(10, "rate GPE %.2x start %lld elapsed %lld count %zu\n", gpe,
+	    pgpe->rate_start, getuptime() - pgpe->rate_start, pgpe->rate_count);
+
+	cycle = getuptime() - pgpe->rate_start;
+	if (cycle >= GPE_RATE_MIN_CYCLE) {
+		if (pgpe->rate_count > (GPE_RATE_MAX * cycle)) {
+			printf("uncontrolled GPE storm %lld/s, disabling GPE %.2x\n",
+			    pgpe->rate_count / cycle, gpe);
+			return (1);
+		}
+
+		/* Reset and start a new cycle */
+		acpi_init_gpe_rate(sc, gpe);
+	}
 	return (0);
 }
 
diff --git sys/dev/acpi/acpivar.h sys/dev/acpi/acpivar.h
index a9b4a2ae9..4e2f47053 100644
--- sys/dev/acpi/acpivar.h
+++ sys/dev/acpi/acpivar.h
@@ -185,6 +185,9 @@ struct gpe_block {
 	void *arg;
 	int   active;
 	int   flags;
+
+	time_t rate_start;
+	size_t rate_count;
 };
 
 struct acpi_devlist {