From 992096868a823a7c114bd06fdc04d53751133290 Mon Sep 17 00:00:00 2001
From: guenther <guenther@openbsd.org>
Date: Sun, 9 Sep 2018 22:46:54 +0000
Subject: [PATCH] pmap_activate() should match cpu_switchto, so set up
 ci_{kern,user}_cr3 if activating for the current thread and meltdown
 mitigations are in effect. Not clear if it's actually possible to hit the
 case where this matters, but it's the Right Thing.

ok mlarkin@
---
 sys/arch/amd64/amd64/pmap.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/sys/arch/amd64/amd64/pmap.c b/sys/arch/amd64/amd64/pmap.c
index 85f23f08568..3b13d45d2fa 100644
--- a/sys/arch/amd64/amd64/pmap.c
+++ b/sys/arch/amd64/amd64/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.117 2018/09/09 22:41:57 guenther Exp $	*/
+/*	$OpenBSD: pmap.c,v 1.118 2018/09/09 22:46:54 guenther Exp $	*/
 /*	$NetBSD: pmap.c,v 1.3 2003/05/08 18:13:13 thorpej Exp $	*/
 
 /*
@@ -1188,6 +1188,14 @@ pmap_activate(struct proc *p)
 	if (p == curproc) {
 		lcr3(pcb->pcb_cr3);
 
+		/* in case we return to userspace without context switching */
+		if (cpu_meltdown) {
+			struct cpu_info *self = curcpu();
+
+			self->ci_kern_cr3 = pcb->pcb_cr3;
+			self->ci_user_cr3 = pmap->pm_pdirpa_intel;
+		}
+
 		/*
 		 * mark the pmap in use by this processor.
 		 */
-- 
2.20.1