Index: aarch64/cpuswitch.S
===================================================================
RCS file: /cvsroot/src/sys/arch/aarch64/aarch64/cpuswitch.S,v
retrieving revision 1.10
diff -p -u -r1.10 cpuswitch.S
--- aarch64/cpuswitch.S	13 Dec 2018 10:44:25 -0000	1.10
+++ aarch64/cpuswitch.S	21 Dec 2018 07:48:42 -0000
@@ -73,6 +73,10 @@ ENTRY_NP(cpu_switchto)
 	str	x5, [x0, #L_MD_CPACR]
 #endif
 
+	/* Save the stack pointer for kvm. */
+	ldr	x6, [x0, #L_PCB]	/* x6 = lwp_getpcb(oldlwp) */
+	str	x4, [x6, #PCB_SP]
+
 	/* We are done with the old lwp */
 
 .Lrestore_lwp:
Index: aarch64/genassym.cf
===================================================================
RCS file: /cvsroot/src/sys/arch/aarch64/aarch64/genassym.cf,v
retrieving revision 1.11
diff -p -u -r1.11 genassym.cf
--- aarch64/genassym.cf	13 Dec 2018 10:44:25 -0000	1.11
+++ aarch64/genassym.cf	21 Dec 2018 07:48:42 -0000
@@ -229,6 +229,8 @@ define	VM_PMAP			offsetof(struct vmspace
 define	SIGTRAP			SIGTRAP
 define	SIGEMT			SIGEMT
 
+define	PCB_SP			offsetof(struct pcb, pcb_sp)
+
 define	TF_X0			offsetof(struct trapframe, tf_reg[0])
 define	TF_X1			offsetof(struct trapframe, tf_reg[1])
 define	TF_X2			offsetof(struct trapframe, tf_reg[2])
Index: include/pcb.h
===================================================================
RCS file: /cvsroot/src/sys/arch/aarch64/include/pcb.h,v
retrieving revision 1.1
diff -p -u -r1.1 pcb.h
--- include/pcb.h	10 Aug 2014 05:47:38 -0000	1.1
+++ include/pcb.h	21 Dec 2018 07:48:42 -0000
@@ -38,6 +38,7 @@
 
 struct pcb {
 	struct fpreg pcb_fpregs;
+	uint64_t pcb_sp;
 };
 
 struct md_coredump {