Hack alert! Apple M1 systems still don't work with an MP kernel.

In order to make progress (and protect myself from things dumping cores
left and right when I run sysupgrade) abuse the hw.smt mechanism to
only schedule processes on the primary CPU.

ok deraadt@, patrick@

2 files changed, 12 insertions, 2 deletions

diff --git a/sys/arch/arm64/arm64/cpu.c b/sys/arch/arm64/arm64/cpu.c
index 8d1618419a7..45694108c29 100644
--- a/sys/arch/arm64/arm64/cpu.c
+++ b/sys/arch/arm64/arm64/cpu.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: cpu.c,v 1.56 2021/10/24 17:52:28 mpi Exp $	*/
+/*	$OpenBSD: cpu.c,v 1.57 2021/11/22 19:22:59 kettenis Exp $	*/
 
 /*
  * Copyright (c) 2016 Dale Rahn <drahn@dalerahn.com>
@@ -605,6 +605,7 @@ cpu_attach(struct device *parent, struct device *dev, void *aux)
 	struct fdt_attach_args *faa = aux;
 	struct cpu_info *ci;
 	uint64_t mpidr = READ_SPECIALREG(mpidr_el1);
+	uint64_t midr = READ_SPECIALREG(midr_el1);
 	uint64_t id_aa64mmfr1, sctlr;
 	uint32_t opp;
 
@@ -643,6 +644,10 @@ cpu_attach(struct device *parent, struct device *dev, void *aux)
 		int timeout = 10000;
 		int len;
 
+		/* XXX SMP on Apple CPUs is busted. */
+		if (CPU_IMPL(midr) == CPU_IMPL_APPLE)
+			ci->ci_smt_id = 1;
+
 		len = OF_getprop(ci->ci_node, "enable-method",
 		    buf, sizeof(buf));
 		if (strcmp(buf, "psci") == 0) {
diff --git a/sys/arch/arm64/include/cpu.h b/sys/arch/arm64/include/cpu.h
index 9f9e4761aae..109dd9c1141 100644
--- a/sys/arch/arm64/include/cpu.h
+++ b/sys/arch/arm64/include/cpu.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: cpu.h,v 1.22 2021/07/06 09:34:06 kettenis Exp $ */
+/* $OpenBSD: cpu.h,v 1.23 2021/11/22 19:22:59 kettenis Exp $ */
 /*
  * Copyright (c) 2016 Dale Rahn <drahn@dalerahn.com>
  *
@@ -92,6 +92,11 @@ struct cpu_info {
 	int			ci_node;
 	struct cpu_info		*ci_self;
 
+#define __HAVE_CPU_TOPOLOGY
+	u_int32_t		ci_smt_id;
+	u_int32_t		ci_core_id;
+	u_int32_t		ci_pkg_id;
+
 	struct proc		*ci_curproc;
 	struct pmap		*ci_curpm;
 	struct proc		*ci_fpuproc;